The Nation's fleet of operating reactors comprises one of four sub-arenas that the staff of the U.S. Nuclear Regulatory Commission (NRC) identified in considering which areas of the reactor safety arena to target for greater use of risk information. This page summarizes the following aspects of the Operating Reactors Sub-Arena:
Objective
Make continuing, incremental improvements in rulemaking, licensing, and oversight of operating reactors, while focusing on implementing existing risk-informed and performance based activities.
This objective focuses on activities that are already in progress to risk-inform the operating reactor subarena, including completed rulemaking activities, guidance documents, and implementation of some initiatives.
The NRC will revisit and update this objective (as appropriate) once the industry has implemented the currently planned activities and feedback becomes available.

Basis
The risk-informed initiatives currently in progress were originally selected using screening criteria similar to those presented in the RPP. Consequently, the five activities (listed below) that support the goals for this subarena satisfy the following screening criteria:
- The risk-informed initiatives that are currently underway help to improve the effectiveness and efficiency of the NRC's regulatory process, including improved safety and reduction of unnecessary regulatory burden.
- Information and analytical models of operating reactors, particularly for at-power operations, exist and are fairly mature.
- The cost-beneficial nature of several of the risk-informed initiatives is evidenced by their voluntary adoption by licensees.
- No factors have been identified to date that would motivate changing the regulatory approach in the areas where risk-informed activities are already underway. Stakeholder feedback substantiates that there is no immediate need to initiate any new risk-informed initiatives, and that the NRC should focus on completing currently identified activities and allowing the industry time to implement those activities.
- Goals and activities to meet the objective for this subarena will be performance-based, to the extent that they meet the following four criteria:
- measurable parameters to monitor performance
- objective criteria to assess performance
- flexibility to allow licensees to determine how to meet the performance criteria
- no immediate safety concern as a result of failure to meet the performance criteria
Risk-informed activities for operating reactors occur in five broad categories:
- applicable regulations
- licensing process
- revised oversight process
- regulatory guidance
- risk analysis tools, methods, and data
The activities in these categories are derived from the Commission's policy statements and guidance, and include revisions to technical requirements in the regulations; risk-informed technical specifications; a new framework for inspection, assessment, and enforcement actions; guidance on other risk-informed applications (e.g., in-service inspections); and improved standardized plant analysis risk models.

Goals
The following goals are derived from the Commission's policy statements and guidance, which reflect the current phase of NRC and industry development, as well as the current implementation of risk-informed activities:
- Finish the development of current risk-informed regulations (e.g., 10 CFR 50.46a rulemaking) and associated regulatory/staff guidance.
- Implement existing NRC risk-informed activities [e.g., risk-informed technical specifications and pilots for 10 CFR 50.69 and the National Fire Protection Association (NFPA) Standard 805].
- Encourage the industry to implement risk-informed rules and approved/endorsed activities.
- Continue making incremental improvements to the established licensing, rulemaking, and oversight activities.
- Modify/update established activities to account for lessons learned.

List of Risk-Informed and Performance-Based Activities
This list shows the ongoing licensing initiatives, projects, and activities that the staff of the U.S. Nuclear Regulatory Commission (NRC) has targeted for greater use of risk information in the Operating Reactors Sub-Arena within the Reactor Safety Arena:
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Summary Description
The objective of this research is to provide support in developing the technical basis for integrating risk insights into the regulatory framework for DI&C systems and components
by: (1) assessing the technical feasibility of risk-informed approaches and gaps associated with further integrating risk insights into regulatory reviews for DI&C systems, and (2) develop recommendations to enhance the use of risk insights within the existing risk-informed regulatory framework for DI&C systems.
FY 2020
FY 2020
A technical letter report detailing the results of the technical feasibility of risk-informed approaches and gaps assessment is being finalized and is expected to be made available in late 2020.
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Use of Systems-Theoretic Accident Model and Processes (STAMP)-based Methods for Digital Nuclear Safety System Evaluation
Summary Description
Current practice for the safety evaluation and analysis of digital safety systems in nuclear power plants has been challenged with changes in the technology, increasing digitization, and increasing interdependencies and interactions across systems and components. The objective of this research effort is to enable the NRC staff to apply STAMP (an accident modeling approach) based methods for performing more effective independent safety analyses, Safety Analysis Report reviews, or causal analysis of operating experience reports with consistent results of digital systems in a risk-informed environment.
FY 2020
FY 2020
This research effort will occur between October 2020 and September 2021. Interactive lectures, seminars, and workshops will be developed for the NRC staff. A report detailing the results is expected by September 2021. The report is expected to include information on the limits within which the STAMP based methods can be consistently applied.
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Technical Assistance for Research on Innovative Methods and Technologies to Enhance Seismic Safety for Design and Construction of Commercial Reactors
Summary Description
The objective of this research is to develop a technology-inclusive (TI), risk-informed and performance-based (RIPB) pathway for ANLWRs to address seismic safety within the LMP framework. Part of the contract will aim at (i) evaluating feasibility and adequacy of potential technical criteria through demonstration studies, (ii) performing communication and outreach activities to help reach consensus with pertinent stakeholders on a viable and practical TI-RIPB approach forward for ANLWR seismic safety (iii) developing associated implementation guidance, and (iv) identifying potential regulatory improvements for future rulemaking activities. The other part of the contract is to identify and evaluate technical criteria for regulatory guidance for the design and review of TI technologies included in licensing application for commercial NPPs. The contract was awarded in June 2020.
FY 2020
FY 2020
We'll not be receiving any deliverables until 2021.
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Technical Assistance for Integration of Risk-Informed Performance Based Approach to Seismic Safety of Nuclear Facilities
Summary Description
The objective of this research is to develop a Risk-Informed Performance Based approach to seismic evaluation consisted with the proposed approach in the Licensing Modernization Project (LMP). This approach has been documented in the draft report, "A Proposed Alternative Risk-Informed and Performance-Based Regulatory Framework for Seismic Safety at NRC Regulated Facilities" (ML20106F035), and was presented to industry and stakeholders in the workshop, "Enhancing Risk-Informed and Performance-Based Seismic Safety for Advanced Non-Light Water Reactors," which was held virtually on September 2-3, 2020.
FY 2020
FY 2020
The final version of the report, "A Proposed Alternative Risk-Informed and Performance-Based Regulatory Framework for Seismic Safety at NRC Regulated Facilities," will be completed and is expected to be published by the end of CY2020.
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Revisions to NUREG-0654, Criteria for Preparation and Evaluation of Radiological Emergency Response Plans and Preparedness for NPP
Summary Description
In December 2019, the NRC and FEMA issued NUREG-0654/FEMA-REP-1, Revision 2, "Criteria for Preparation and Evaluation of Radiological Emergency Response Plans and Preparedness in Support of Nuclear Power Plants." This is one of the key guidance documents for developing and evaluating onsite and offsite emergency plans for nuclear power plants and for State and Local government emergency response organizations. A risk-informed approach was taken in the development of the guidance, specifically in relation to Table B-1, "Emergency Response Organization (ERO) Staffing and Augmentation Plan," which re-evaluated the staffing levels and augmentation timing for licensee emergency responders.
FY 2020
FY 2020
NSIR staff are currently reviewing licensee ERO staffing change as license amendment requests (LAR) are received. In addition, NSIR staff are reaching out to industry on potential LARs to re-baseline emergency plans using the latest guidance in Revision 2 to NUREG-0654 guidance to reduce level of unnecessary detail in plan and relocating to EPIPs to allow greater licensee flexibility to implement changes to their EP programs under 10 CFR 50.54(q) process without prior NRC approval.
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Revision to NUREG/CR-7002, "Criteria for Development of Evacuation Time Estimate Studies"
Summary Description
NSIR developed draft Revision 1 to NUREG/CR-7002, "Criteria for Development of Evacuation Time Estimate Studies," (ML20233A700) based on risk insights from an applied research study on evacuation time estimates (ETE) published in March 2020, as NUREG/CR-7269, "Enhancing Guidance for Evacuation Time Estimate Studies," (ML20070M158). Risk-informed revisions to the ETE guidance include updated considerations for when to include a shadow evacuation, the use of manual traffic control, establishing appropriate boundary conditions, the use of dynamic traffic assignment, and updates to modeling adverse weather. Risk insights were also applied to develop updated measures of effectiveness to demonstrate model performance
FY 2020
FY 2020
Draft Revision 1 to NUREG/CR-7002 was released for public comment on August 27, 2020. NSIR staff held a public meeting on the proposed revisions on September 16, 2020. The staff expects to publish Revision 1 by the end of CY 2020 in time to support decennial updates to ETEs which will start around April 1, 2021.
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Power Reactor Cyber Security Program Improvements
Summary Description
Based on lessons learned from implementation and oversight of the NRC's cyber security requirements (10 CFR 73.54), the NRC staff is working to improve the efficiency and effectiveness of the power reactor cyber security program. Specifically, the NRC staff is seeking to further risk-inform the program in areas such as the following: Critical Digital Asset Determination, Protection (Cyber Control Implementation), and Assessment, as well as Cyber Inspection Oversight Program. Examples of risk-informed activities being performed under this effort include: (1) Evaluating cyber security controls to ensure that they are appropriate for the types of technology (i.e., Information Technology versus Operational Technology) implemented in the licensee's digital infrastructure; and, (2) Providing greater definition to the guidance to screen cyber security controls that are not needed or applicable based on risk-informed analysis (e.g., Critical Digital Asset system capability and complexity).
FY 2020
FY 2020
NSIR has issued letters on industry use of guidance for emergency preparedness digital assets (ADAMS Accession No. ML20129J981), balance of plant digital assets (ADAMS Accession No. ML20209A442), and for important-to-safety and safety-related digital assets (ADAMS Accession No. ML20223A256).
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Ensure Force-on-Force (FoF) Scenarios Are Realistic and Reasonable
Summary Description
The staff of the NRC's Office of Nuclear Security and Incident Response has adjusted internal office processes to incorporate threat assessment information into the exercise scenario development process. This includes: increasing management attention to the exercise scenarios; increasing the use of intelligence analysis to benchmark tactics used by the mock adversary force; and inventorying tactics, techniques and procedures used during previous FOF exercises, categorizing based on complexity for use as a management tool during the scenario evaluation process.
Previous Fiscal Years
FY 2018
In FY2019, the staff intends to take a number of initiatives on this topic. As directed in SRM-SECY-17-0100, the staff will develop and implement a revised Force-on-Force inspection process, using risk-informed insights during the evaluation of internal and external stakeholder recommendations for proposed improvements. In the process, the staff will evaluate alternatives for the FoF program mock adversary force. Finally, the staff anticipates endorsing an industry-initiated FoF exercise controller guidance document.
FY 2019
NSIR staff submitted COMSECY-19-0006, which presented options for the implementation of a revised Force-on-Force inspection process, using risk-informed insights based on the evaluation of internal and external stakeholder recommendations for proposed improvements.
In addition, in FY 2019, NSIR staff began the development of a scoring system to be used in the development of FoF exercise scenarios. The system will ensure the appropriate level of insider knowledge is used during scenario development and that scenarios realistically consider the threat environment. This scoring system will include a benchmarking with U.S. Department of Energy (DOE) staff to incorporate lessons learned and best practices from DOE's use of a scoring system. The staff intends to begin using the scoring system in Q2 of FY 2020.
FY 2020
FY 2020
NSIR staff is adjusting internal office processes to incorporate threat assessment information into the exercise scenario development process. This includes: increasing management attention to the exercise scenarios; increasing the use of intelligence analysis to benchmark tactics used by the mock adversary force; developing a scoring system, which considers the level of insider knowledge applied, to help ensure that exercises scenarios are consistently reasonable and realistically consider the threat environment; and inventorying tactics, techniques and procedures used during previous FOF exercises, categorizing based on complexity for use as a management tool during the scenario evaluation process.
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Risk-Informed Compensatory Measures
Summary Description
Licensees would be able to use a more risk-informed process to determine implementing timeframes for security compensatory measures, based on site-specific threat conditions.
Previous Fiscal Years
FY 2018
This is anticipated to be accomplished through approval of an industry proposal.
FY 2019
NSIR staff finalized a risk-informed process to determine implementing timeframes for security compensatory measures, based on site-specific threat conditions. This work followed NRC's approval for use of revised NEI 03-12, "Template for Security Plan, Training and Qualification, Safeguards Contingency Plan, [and Independent Spent Fuel Storage Installation Security Program]," particularly Section 21, "Compensatory Measures." As part of this process, NSIR staff provided presentations to security inspectors and Resident Inspectors in each of the four Regions and briefed industry security managers on the activities to ensure mutual understanding of the new process.
FY 2020
FY 2020
This revised process has been implemented. The Security Issues Forum (SIF) is used to promote consistency during regional inspection activities.
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Consequence-based Security for Advanced Reactors
Summary Description
The NRC first issued its Policy Statement on the Regulation of Advanced Reactors on July 8, 1986, in Volume 51 of the Federal Register, page 24643 (51 FR 24643), with an objective to provide all interested parties, including the public, with the Commission's views concerning the desired characteristics of advanced reactor designs. The NRC revised the policy statement in 2008 (73 FR 60612; October 14, 2008) to specifically include attributes related to physical security that should be considered in advanced designs. In particular, the Commission observed that it would be in the interest of the public as well as the design vendors and the prospective license applicants to address security issues early in the design stage.
Accordingly, and with the resurgence in potential for applications for advanced reactor designs, the NRC is analyzing associated physical security requirements that are commensurate with the potential consequences to public health and safety and common defense and security from the possession and use of special nuclear material at these facilities.
Previous Fiscal Years
FY 2018
The staff transmitted a Notation Vote paper (ML18052B032) to the Commission in August, 2018. The paper provides the Commission options for addressing physical security requirements for advanced reactors, and recommends a limited-scope revision of regulations and guidance to reflect the relative risks posed by the technology.
FY 2019
On November 19, 2018, the Commission approved the staff's recommendation (Option 3) to initiate a limited-scope rulemaking according to the rulemaking plan (as modified) in Staff Requirements Memorandum SECY-18-0076," Staff Requirements SECY-18-0076, Options and Recommendation for Physical Security for Advanced Reactors." On July 16, 2019, the staff issued the Regulatory Basis for public comment. The comment period closed on August 15, 2019. Nine comments were received and are to be addressed in the proposed rule. Currently, as scheduled, the proposed rulemaking and draft guidance will be provided to the Commission in January 2021, and if approved, will be published for public comment. The Final Rule and Final Guidance are currently scheduled to be provided to the Commission in May 2022.
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Revision of the Emergency Preparedness Significance Determination Process
Summary Description
The NRC staff is evaluating possible changes to the process to ensure significance of emergency preparedness inspection findings are appropriately characterized using risk principles. The NRC initiated a focused self-assessment of the significance determination process for emergency preparedness-related licensee performance deficiencies, with the objective of determining whether improvements can or should be made to this established process.
Previous Fiscal Years
FY 2018
The staff expects to complete the self-assessment in February 2019 and summarize the results in the annual Reactor Oversight Program's self-assessment paper to the Commission.
FY 2019
NSIR completed the Emergency Preparedness (EP) Significance Determination Process focused self-assessment (EP SDP FSA) in February 2019, including recommendations for further action/review (ML18331A374). NSIR staff assisted in incorporating these recommendations into the Reactor Oversight Process Enhancement Project and contributed to the development of SECY-19-0067, "Recommendations for Enhancing the Reactor Oversight Process to obtain Commission direction on the higher priority recommendations. NSIR staff continues to work on other recommendations that do not require Commission approval, for example, revising the EP training program, developing tools for better communication, sharing of regional operating experience, and formalizing knowledge management. The staff expects to complete the recommendation(s) that do not require Commission direction during FY 2020 and FY 2021.
FY 2020
FY 2020
NSIR staff revised the EP inspector training qualification program and conducted a pilot in October 2020 and a training session in May 2020. Additionally, NSIR staff developed an online web-based EP Fundamentals course that was available in TMS on Sept 28, 2020. Staff developed and is using a knowledge management SharePoint file to capture discussions related to EP inspections. Regional EP inspectors regularly add content as issues arise.
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Baseline Security Program Revision
Summary Description
The NRC staff will use risk-informed insights to ensure that the concept of "high assurance" of adequate protection, as found in NRC security regulations, is equivalent to "reasonable assurance" when it comes to determining what level of regulation is appropriate. Significant accomplishments to date include: revising the associated significance determination process (SDP) to appropriately categorize findings related to the handling of safeguards material; and incorporating risk-informed insights to revise the staff's site access authorization process to improve the program's efficiency and effectiveness, standardize requirements across the agency, and reduce the training requirement to a five-year periodicity.
Previous Fiscal Years
FY 2018
In FY 2019, the staff plans to: continue with the SDP revision process to implement additional changes to align the security inspection program with the Reactor Oversight Process, reflect the staff's commitment to the risk-informed process and ensure findings are characterized using risk principles where appropriate; review and revise the baseline security inspection procedures to streamline the inspection process and apply the concept of reasonable assurance; and use risk-informed insights during the evaluation of internal and external stakeholder recommendations for proposed changes to the inspection manual chapters and inspection procedures.
FY 2019
NSIR staff continued to use risk-informed insights to ensure that the concept of "high assurance" of adequate protection, as found in NRC security regulations (10 CFR 73.20 and 73.55), is equivalent to "reasonable assurance" when it comes to determining what level of regulation is appropriate. To accomplish this goal, NSIR staff further refined how it revises the significance determination process, implementing additional changes to align the security inspection program with the Reactor Oversight Process, ensuring findings are characterized using risk principles where appropriate. In addition, staff reviewed and revised multiple baseline security inspection procedures to streamline the inspection process, using risk-informed insights during the evaluation of internal and external stakeholder recommendations for proposed changes to the inspection manual chapters and inspection procedures.
FY 2020
FY 2020
Due to COVID-19 restrictions, on-site security inspections were interrupted. In an effort to continue to provide regulatory oversight, security inspectors were able to partially complete baseline security inspections remotely. Once travel restrictions were lifted, security inspectors were able to complete the remaining portions of the inspection procedure. NRC staff will leverage lessons learned during the COVID-19 public health emergency to improve the efficiency of the baseline inspection program where appropriate.
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State-of-the-Art Reactor Consequence Analyses
Summary Description
The state-of-the-art reactor consequence analyses (SOARCA) project was initiated to evolve our understanding of the consequences of important severe accident scenarios at selected U.S. nuclear power plants including Peach Bottom, a BWR in Pennsylvania; Surry, a PWR with a large dry containment in Virginia; and Sequoyah, a PWR with an ice condenser containment in Tennessee. The project has focused on detailed modeling of accident progression using MELCOR and offsite consequences using MACCS (MELCOR Accident Consequence Code System). MELCOR models the severe accident processes within the plant to the point of release of fission products to the environment. MACCS models the atmospheric transport and deposition of radionuclides released to the environment as well as emergency response and long-term protective actions, exposure pathways, dosimetry, and health effects for the affected population. Staff conducted uncertainty analyses (UA) of a subset of the scenarios to better understand the range of potential outcomes for these accidents and what drives key phenomena. Each UA included hundreds of simulations to account for uncertainty in MELCOR and MACCS input parameters and the results help corroborate the project's overall conclusions.
By its nature SOARCA focuses on the consequences of accidents rather than on their likelihood or on the many redundant safety systems, components, procedures, training, strategies, or the recently added backup mitigation equipment required following the Fukushima Dai-ichi nuclear power plant accident in Japan. Plant safety features and added mitigation capability drive down the likelihood of a severe accident but not necessarily the consequences. The study of the unmitigated consequences of a severe accident does not dismiss or under-value those safety features, rather it sheds light on their importance by providing insights into the possible consequences they are intended to prevent. SOARCA project's results, insights, computer code models, and modeling best practices have supported NRC rulemaking, licensing, and oversight efforts. SOARCA supported SECY-15-0137 and SECY-16-0041 which closed NRC's evaluation of post-Fukushima recommendations related to containment vents and hydrogen control and mitigation.
Previous Fiscal Years
FY 2018
In FY 2018 the staff completed calculations for an updated UA of the Surry unmitigated short-term station blackout scenario. Updated calculations were important to leverage insights from the Sequoyah UA (NUREG/CR-7245).
FY 2019
Previously, the staff completed deterministic and sensitivity analyses of Peach Bottom and Surry which are documented in NUREG-1935, NUREG/CR-7110, and NUREG/BR-0359 and a UA for the Peach Bottom unmitigated long-term station blackout is documented in NUREG/CR-7155. In FY 2019, staff completed a UA of the unmitigated STSBO for Surry and prepared formal documentation in a NUREG/CR report. Staff began development of a Research Information Letter to formally document the numerous benefits and uses of the SOARCA project beyond its original objectives including uses by the NRC, reactor licensees and applicants, domestic and international regulatory and research organizations, academia, and other stakeholders. Finally, to complete the work on the SOARCA Project, staff began development of a summary report capturing the most important accident progression and consequence analysis insights from the three SOARCA uncertainty analyses is being compiled.
FY 2020
FY 2020
In FY 2020 staff completed a Research Information Letter (RIL-2020-03) that formally documents the numerous benefits and uses of the SOARCA project beyond its original objectives including uses by the NRC, reactor licensees and applicants, domestic and international regulatory and research organizations, academia, and other stakeholders. Staff also completed an updated revision of the SOARCA brochure, NUREG/BR-0359, Rev. 3, "Modeling Potential Reactor Accident Consequences" to capture updates from the more recently completed SOARCA uncertainty analyses. The UA of the unmitigated STSBO for Surry is still awaiting final submittal to publication as NUREG/CR-7262. Staff continues to make progress on the SOARCA UA summary report which seeks to capture the most important accident progression and consequence analysis insights from the three SOARCA UA. This summary document is a concise reference that will support risk-informed decisionmaking.
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Probabilistic Methodologies for Component Integrity Assessment
Summary Description
The U.S. Nuclear Regulatory Commission (NRC) has considered insights drawn from probabilistic methodologies for component integrity assessment as part of its regulatory decision-making for several decades. The use of probabilistic methods moves the agency further towards risk-informed decision-making, which is a stated policy goal of the NRC. Furthermore, the NRC needs methodologies and procedures that enable it to perform an educated, thoughtful review of probabilistic methods proposed by the industry. The NRC currently has several active projects related to probabilistic methodologies for component integrity assessment: (1) maintenance and improved verification and validation of the Fracture Analysis of Vessels – Oak Ridge (FAVOR) code, (2) distribution, maintenance, and application of the Extremely Low Probability of Rupture (xLPR) code, and (3) development of a probabilistic fracture mechanics (PFM) Regulatory Guide.
The NRC and the U.S. nuclear industry have used probabilistic methods to inform their evaluation of postulated pressurized thermal shock (PTS) of reactor pressure vessels (RPVs) since the 1980s. In the original PTS rule (10 CFR 50.61) probabilistic evaluations provided complementary information to deterministic evaluations, and the reference temperature (RTPTS) screening criteria in 10 CFR 50.61 relate to a vessel failure frequency of ≈5×10-6 events / reactor operating year. Several PFM codes were used in the 1980s, including VISA (Vessel Integrity Simulation Analysis) and OCA-P (Over Cooling Accident - Pressurized). In the mid-1990s these codes were combined to generate the FAVOR code, which later provided computational support for the technical basis of the alternate PTS rule, 10 CFR 50.61a. FAVOR has since found other applications (e.g., risk-informed pressure-temperature limits, evaluation of nil-ductility transition [RTNDT] uncertainties, and evaluation of quasi-laminar flaws), although these other applications have not garnered generic regulatory acceptance. In a separate activity, NRC and the Electric Power Research Institute (EPRI) have collaboratively developed the xLPR Version 2 PFM code to assess the effects of active degradation mechanisms on nuclear power plant piping systems approved for leak-before-break (LBB). Specifically, beginning around the year 2000, primary water stress-corrosion cracking (PWSCC) was discovered in systems that had previously been approved for LBB based on the assumed absence of active degradation mechanisms, in accordance with Standard Review Plan 3.6.3. As a result of the discovery of the PWSCC mechanism, an extremely low probability of rupture could no longer be demonstrated by the deterministic methods outlined in NUREG-0800, but would instead need to be addressed probabilistically, for instance by using a PFM code such as xLPR. Technical development of the full production version of the code is now complete. Various activities were undertaken during the development phase to build confidence into the code, including a broad team of experts from diverse backgrounds, a rigorous quality assurance program, comprehensive verification and validation, and extensive documentation.
With the release of FAVOR v16.1 and xLPR v2, PFM use by the U.S. nuclear industry is expected to increase, as PFM may be used to develop a technical basis for relief requests, license amendments, and topical reports. Uncertainty is addressed differently in PFM when compared to deterministic fracture mechanics. In PFM, a single deterministic (usually conservative) analysis is replaced by many deterministic analyses that use randomly sampled inputs. Statistical analyses are then performed on the collection of outputs obtained to determine the probability of an event of interest. Unfortunately, it is difficult for NRC staff to reproduce or verify PFM calculations submitted by licensees, thus resulting in complex regulatory reviews. In particular, NRC staff has often perceived PFM codes as 'black boxes' with insufficient vetting of the models and the uncertainty framework. This has resulted in low confidence in the results of PFM analyses. As a result, the NRC has begun developing guidance for performing and documenting PFM analyses for regulatory applications. Specifically, NRC's Office of Nuclear Regulatory Research has been tasked with developing a PFM Regulatory Guide (RG). The process of developing the RG involves publication of a Technical Letter Report, a technical basis NUREG, and the Draft RG itself. The Technical Letter Report was published in September 2018 and is available at ML18235A013.
Previous Fiscal Years
FY 2018
A recent release of FAVOR, Version 16.1, includes updated fracture driving force solutions for surface-breaking flaws and the ability to analyze both heat-up and cool-down transients in the shell coarse region of both pressurized water reactor (PWR) and boiling water reactor designs. Planned efforts are underway to assess potential safety issues related to shallow subsurface flaws, including warm pre-stress effects, cladding residual stress modeling, and an assessment of risk-optimized pressure-temperature corridors for RPV heat-up and cooldown. NRC and EPRI have agreed on a framework for U.S. domestic distribution of xLPR and are currently pursuing coordinated efforts to apply xLPR to conduct probabilistic LBB studies for the U.S. fleet of PWRs. A Technical Letter Report on important aspects to be considered for PFM has been produced and lays the foundation for the upcoming development of the PFM RG and its technical basis.
PFM is typically used to determine the likelihood of a component failure, or the likelihood of a precursor to component failure. As such, PFM can answer one of the two fundamental questions in risk assessment: what is the initiating event frequency or likelihood of occurrence? The other question that PFM does not address is: what are the consequences of such an event occurring? In addition to the likelihood of an event, PFM can also be used to determine confidence bounds on the probability of an event of interest.
FY 2019
In the nuclear power plant piping area, the NRC completed sensitivity studies concerning the Extremely Low Probability of Rupture (xLPR) Version 2 code to identify which of its models and inputs contribute most to uncertainty in its outputs. As part of this effort, NRC-sponsored sensitivity study methodologies were compared against industry-sponsored methodologies, and it was demonstrated that all of the methodologies produced similar findings that the crack initiation models drive uncertainties. The NRC also began to apply xLPR Version 2 to conduct probabilistic analyses to quantify the risks of primary water stress-corrosion cracking in pressurized-water reactor piping systems which have received NRC approval for leak-before-break under 10 CFR Part 50, Appendix A, General Design Criterion 4. The NRC analysis methodologies and results are being compared against results generated independently by industry-sponsored analysts also using xLPR Version 2. In addition, the NRC transitioned xLPR Version 2 from the development to the maintenance phase of the software lifecycle under a rigorous quality assurance program. To strengthen confidence in the xLPR Version 2 analysis results, the NRC initiated an effort to benchmark the code against the probabilistic fracture mechanics analysis code, PASCAL-SP (Probabilistic Fracture Mechanics Analysis of Structural Components in Aging Light-Water Reactors - Stress-Corrosion Cracking at Welded Joints of Piping), which has been independently developed by the Japan Atomic Energy Agency. Comparison of the analysis results produced by the two codes indicate that they provide similar results when exercising their core fracture mechanics models. The NRC also applied xLPR Version 2 to assess conservatism in loss-of-coolant accident frequencies presented in NUREG-1829, "Estimating Loss-of-Coolant Accident (LOCA) Frequencies Through the Elicitation Process." The results were discussed with the Advisory Committee on Reactor Safeguards in relation to ongoing NRC evaluations of licensee actions in response to Generic Safety Issue 191, "Assessment of Debris Accumulation on PWR Sump Performance."
In the nuclear power plant vessel area, analysis work using the Fracture Analysis of Vessels-Oak Ridge (FAVOR) Version 16.1 code to address potential safety issues related to shallow subsurface flaws is nearing completion, including investigations of warm pre-stress effects, cladding residual stress modeling, and an assessment of risk-optimized pressure-temperature corridors for vessel heat-up and cool-down. In addition, NRC staff received extensive training in the use and development of the FAVOR probabilistic vessel integrity assessment code. The Reactor Embrittlement Archive Project (REAP) database has also been reactivated as a web-based search tool for worldwide users.
Finally, a Technical Letter Report on important aspects to be considered for probabilistic fracture mechanics was published early in 2019. It lays the foundation for the upcoming publication of the draft probabilistic fracture mechanics regulatory guide and its associated technical basis. The NRC developed a proposal for a graded approach for regulatory submittals based on probabilistic fracture mechanics, largely based on stakeholder feedback received at public meetings during 2019. This approach was presented at the 3rd International Seminar on Probabilistic Methods for Nuclear Applications (ISPMNA'19), which NRC hosted in October 2019 in Rockville, MD.
FY 2020
FY 2020
In the nuclear power plant piping area, the NRC engaged in a several activities concerning the Extremely Low Probability of Rupture (xLPR) probabilistic fracture mechanics (PFM) code. Foremost, the NRC publicly released xLPR Version 2.1 to users worldwide. Public release was made possible by re-negotiating distribution arrangements with the Electric Power Research Institute, the code's co-developer. The NRC sponsored five public webinars to announce public release of the xLPR code and provide information to new users. Recordings of these webinars are available for public viewing on the NRC YouTube channel. Public release was also supported by development of xLPR Version 2.1, which marked the first incremental release of the code. Version 2.1 was built and tested following rigorous software quality assurance practices and includes updated leak rate calculations through incorporation of new water property routines supplied by the National Institute of Standards and Technology, among other updates. Public release of the xLPR code garnered significant global interest with further growth of the user base expected. Members of the public may request the code by following the procedures on the NRC's Obtaining the Codes webpage. The NRC also conducted a host of studies using the code to quantify the risks of primary water stress-corrosion cracking in pressurized-water reactor piping systems which have received NRC approval for leak-before-break under 10 CFR Part 50, Appendix A, General Design Criterion 4. In addition, a draft NUREG manuscript, which summarizes the entire xLPR Version 2.0 development effort and underlying theory and operations of the code, was prepared. Finally, a project was initiated through the International Atomic Energy Agency to benchmark xLPR against other PFM codes throughout the world.
In the nuclear power plant vessel area, progress was made towards developing a new version of the Fracture Analysis of Vessels-Oak Ridge (FAVOR) PFM code, named Version 20.1. The updated version will allow for the modeling of as-found flaws and include updated user and theory manuals, as well as the associated software quality assurance and verification and validation documentation and test suite.
To support increased use of PFM in nuclear applications in general, the NRC readied a draft regulatory guide and accompanying technical basis NUREG for public comment. This work expanded significantly upon the foundations laid in and stakeholder feedback on the prior Technical Letter Report on important aspects to be considered for PFM applications. Additionally, the NRC brought together PFM experts from around the world by hosting the 3rd International Seminar on Probabilistic Methods for Nuclear Applications in Rockville, MD.
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Implementing Lessons Learned from Fukushima
Summary Description
Following the accident at the Fukushima Dai-ichi Nuclear Plant in Japan, the NRC initiated actions to evaluate lessons learned and to implement appropriate changes in nuclear power plant designs and procedures. Initial recommendations were included in the Near Term Task Force (NTTF) report entitled "Recommendations for Enhancing Reactor Safety in the 21st Century." Several of the items (e.g., Recommendation 1 regarding improving the regulatory framework and recommendation 2.1 on re-evaluating seismic and flooding hazards) include incorporation of risk-informed, performance-based approaches into NRC activities. The status and program plans for items identified for longer term evaluations were reported to the Commission in SECY 12-0095. Recommendation 1 was closed by the Commission without approving staff proposed improvement activities in SRM-SECY-13-0132. For NTTF recommendation 2.1-Seismic, some licensees are using a probabilistic seismic hazard approach in their responses to NRC's request for updated seismic hazard information. More information is available from the Japan Lessons Learned Web site.
Previous Fiscal Years
FY 2015
Licensees submitted updated seismic hazard information in FY 2014 and, if required, "expedited seismic evaluation process" results in FY 2015. The updated hazard information and other factors (e.g., risk insights from the Individual Plant Examination of External Events for Severe Accident Vulnerabilities) were used to determine whether certain plants need to perform a seismic risk assessment, (on the order of 20 sites screened in for performing the risk assessment.) For those sites, NRC will use that information as part of the determination of whether additional regulatory action is warranted.
FY 2016
The NRC staff made significant progress in developing the infrastructure to support its review of licensees' submittals of the results of their seismic probabilistic risk assessments (PRAs). The first such submittal is expected to be received in the first quarter of calendar year 2017.
FY 2017
The NRC completed the development of the infrastructure to support the review of licensees' seismic PRA submittals. The NRC received three seismic PRA submittals, on a staggered schedule over the course of the year, and began implementing the review process. The first staff assessment of a seismic PRA submittal is expected to be issued by the NRC in the first quarter of calendar year 2018. The NRC expects to receive five more seismic PRA submittals in 2018, and the remainder of the seismic PRA submittals in 2019, all on a staggered schedule. More information on this risk-informed initiative can be found on the NRC's Seismic Reevaluations Web page.
FY 2018
The NRC staff received 7 seismic PRA submittals and issued staff assessments of 3 submittals in 2018. More information on this risk-informed initiative can be found on the NRC's Seismic Reevaluations Web page.
The risk insights from the seismic PRAs will be used by the staff to evaluate the impact of the site-specific reevaluated seismic hazard and determine whether further regulatory actions are warranted.
FY 2019
The NRC staff received 3 seismic PRA submittals and issued staff assessments for 4 submittals (one of the assessments was for a submittal received in FY 2018). The staff uses risk insights from the seismic PRA submittals to evaluate the impact of the site-specific reevaluated seismic hazard and determine whether further regulatory actions are warranted on a plant-specific basis. Several licensees have considered the risk insights from their seismic PRAs to identify and voluntarily undertake plant modifications for safety enhancement. For more information on this risk-informed initiative, please see Plant-Specific Japan Lessons-Learned Activities.
FY 2020
FY 2020
The NRC staff received seismic PRA submittals for 6 sites and issued staff assessments for 8 sites (2 assessments were for sites that submitted seismic PRAs in FY 2019). The staff uses risk insights from the seismic PRA submittals to evaluate the impact of the site-specific reevaluated seismic hazard and determine whether further regulatory actions are warranted on a plant-specific basis. The NRC staff completed all its seismic PRA and flooding reviews during FY 2020 using a risk-informed approach. Similarly, the NRC staff received external flooding IA submittals for 2 sites and issued staff assessments for 3 sites (1 staff assessment was for a site that submitted its IA in FY 2019). The staff uses information on the impact of flooding on key safety features, the available physical margin, and licensee actions to evaluate the impact of the site-specific reevaluated external flooding hazard and determine whether further regulatory actions are warranted on a plant-specific basis.
Several licensees leveraged risk insights from their seismic PRAs and external flooding assessments to identify and voluntarily undertake plant modifications. The NRC staff's efforts, coupled with licensee identified modifications, have resulted in safety enhancements and an improved ability to cope against the reevaluated hazards.
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Accident Sequence Precursor (ASP) Program
Summary Description
In 1979, the U.S. Nuclear Regulatory Commission (NRC) established the ASP Program in response to the Risk Assessment Review Group report issued in September 1978 (NUREG/CR-0400, "Risk Assessment Review Group Report to the U.S. Nuclear Regulatory Commission"). The evaluations performed for events that occurred between 1969 and 1979 were the first efforts in this type of analysis. The ASP Program systematically evaluates U.S. nuclear power plant operating experience to identify, document, and rank operational events by calculating a conditional core damage probability (CCDP) or an increase in core damage probability (ΔCDP).
The ASP Program identifies potential precursors by reviewing operational events from licensee event reports on a plant unit basis. An operational event can be one of two types: (1) the occurrence of an initiating event, such as a reactor trip or a loss of offsite power, with or without any subsequent equipment unavailability or degradation; or (2) a degraded plant condition characterized by the unavailability or degradation of equipment without the occurrence of an initiating event.
For the first type of event, the staff calculates a CCDP. This metric represents a conditional probability that a core damage state is reached given the occurrence of the observed initiating event (and any subsequent equipment failures or degradations). For the second type of event, the staff calculates a ΔCDP. This metric represents the increase in core damage probability for the time period during which a component or multiple components were deemed unavailable or degraded.
Starting in 2006, to minimize overlap and improve efficiency, Significance Determination Process (SDP) results have been used in lieu of independent ASP analyses to the extent practical and consistent with the overall objectives of both programs. More information regarding the details of this change is documented in NRC Regulatory Issue Summary 2006-24.
The ASP Program is one of three agency programs that assess the risk significance of issues and events. The other two programs are the Reactor Oversight Process and the event response evaluation process, as defined in Management Directive 8.3, "NRC Incident Investigation Program." In contrast to the other two programs, a comprehensive and integrated risk analysis under the ASP Program includes all anomalies observed at the time of the event or discovered after the event. These anomalies may include unavailable and degraded plant structures, systems, and components (SSCs); human errors; and/or an initiating event (e.g., reactor trip). An unavailable or degraded SSC does not have to be a performance deficiency (PD) or an analyzed condition in the plant design basis, as required in the SDP. The ASP Program analyzes concurrent, multiple PDs or degraded conditions together, unlike the SDP that analyzes PDs individually.
Previous Fiscal Years
FY 2015
The ASP Program independently identified five precursor events in Fiscal Year (FY) 2015. In addition, four precursor events were analyzed by the SDP and accepted into the ASP Program (as described in NRC Regulatory Issue Summary 2006-24). See SECY-15-0124, "Status of the Accident Sequence Precursor Program and the Standardized Plant Analysis Risk Models," for more information on the status of the ASP Program for FY 2015.
FY 2016
In FY 2016, the ASP Program implemented a variety of administrative changes. In accordance with Project AIM, and by direction of the Commission, the status of the ASP Program will no longer be reported in the annual SECY paper "Status of the Accident Sequence Precursor Program and the Standardized Plant Analysis Risk Models." Instead, an annual summary of the ASP Program will be provided as a publicly available document. In addition, the ASP Program transitioned from a FY reporting cycle to a calendar year (CY) reporting cycle. Operational events will be organized based on the CY in which the licensee event report is submitted to the NRC. As part of this transition, the FY 2015 annual report was combined with the CY 2016 report. Annual summary reports will be made available to the public in the following CY (e.g., the CY 2016 annual report was made available to the public in CY 2017).
The NRC's Risk-Informed Steering Committee initiated an internal evaluation of the ASP Program in July 2016, performed by staff within the Office of Nuclear Reactor Regulation. A public meeting was held on October 13, 2016, to solicit feedback from external stakeholders and members of the public (see the meeting summary for additional information).
FY 2017
In FY 2017, the ASP Program published the "U.S. Nuclear Regulatory Commission Accident Sequence Precursor Program 2016 Annual Report," which summarizes the results of ASP analyses for events reported between October 2014 and December 2016. Twenty-three events were determined to be precursors. Of these 23 precursors, 15 precursors utilized SDP results in accordance with RIS 2006-24 and the remaining 8 precursors were identified via independent ASP analyses. Three of the events identified by ASP analyses had a CCDP or ΔCDP greater than or equal to 1x10-5.
The NRC continues its internal evaluation of the ASP Program with a focus on identifying resource efficiencies through process changes, increasing the use of ASP results in other NRC processes, and ensuring timeliness of ASP analyses to support internal and external stakeholder needs. Recommended changes to the ASP Program will likely be communicated in early FY 2018.
FY 2018
In FY 2018, the ASP Program published the "U.S. Nuclear Regulatory Commission Accident Sequence Precursor Program 2017 Annual Report," which summarizes the results of ASP analyses for events reported in CY 2017. Eleven events were determined to be precursors. Of these 11 precursors, three precursors utilized SDP results in accordance with RIS 2006-24 and the remaining eight precursors were identified via independent ASP analyses. Six of the events identified by ASP analyses had a CCDP or ΔCDP greater than or equal to 1x10-5.
The NRC completed its internal evaluation of the ASP Program in February 2018. The ASP Program has implemented the recommendations made by NRC management. Additional information on the internal ASP Program review, including conclusions and recommendations, is available.
FY 2019
In FY 2019, the ASP Program published the "U.S. Nuclear Regulatory Commission Accident Sequence Precursor Program 2018 Annual Report," which summarizes the results of ASP analyses for events reported in CY 2018. Six events were determined to be precursors. Of these six precursors, three precursors utilized SDP results in accordance with RIS 2006-24 and the remaining three precursors were identified via independent ASP analyses. CY 2018 was the first time in ASP Program history in which no precursors with a CCDP or ΔCDP greater than or equal to 1x10-5 were identified.
Historically, ASP analyses have been focused on the risk due to internal events unless an external hazard (e.g., fires, floods, seismic) resulted in a reactor trip (e.g., seismically induced loss of offsite power) or a degraded condition was specific to an external hazard (e.g., degraded fire barrier). This limitation was due to lack of external event modeling in the Standardized Plant Analysis Risk (SPAR) models for all plants. However, the incorporation of seismic hazards in all SPAR models was completed in December 2017. Therefore, the decision was made to evaluate seismic risk for all degraded conditions. The inclusion of seismic hazard risk in ASP analyses will improve the SPAR models by identifying issues and insights specific to seismic scenarios. Seismic hazards were not a significant risk impact in any 2018 ASP analysis.
FY 2020
FY 2020
In FY 2020, the ASP Program published the "U.S. Nuclear Regulatory Commission Accident Sequence Precursor Program 2019 Annual Report," which summarizes the results of ASP analyses for events reported in CY 2019. Only two events were determined to be precursors, which is a historical low. Both precursors were evaluated via an independent ASP analysis. There were no greater than Green inspection findings with risk impacts to core damage identified in 2019. For the second year in a row, no precursors with a CCDP or ΔCDP greater than or equal to 1x10-5 were identified.
The 10-year precursor occurrence rates for all precursors and most precursor subgroups (e.g., high-risk precursor, initiating events, degraded conditions, LOOPs, and precursors occurring at PWRs) exhibit a statistically significant decreasing trends. No trend exists for precursors occurring at BWRs or from emergency diesel generator failures for the past decade, which are the only precursor trends not decreasing. In addition to the decreasing precursor occurrence rates, the integrated ASP index shows a decreasing overall risk due to precursors. The number of LERs and potential precursors identified continues to decrease to historical lows. These results and insights support the conclusion that current oversight programs and licensee activities remain effective.
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Design Compliance Enforcement Discretion (DCED): a Risk-Informed Approach for Addressing Low Risk, Low Safety Significance Design Compliance Issues
Summary Description
The agency is developing a risk-informed approach to resolve licensee design issues that render a technical specification structure, system or component inoperable and are determined to be of low risk/low safety significance. The goal is to provide a tool to the staff that provides a risk-informed alternative to enforcement of technical specification compliance when it can be demonstrated that the non-compliance does not pose an undue risk to public health and safety.
The staff envisions developing a risk-informed process that would ensure that the level of licensee and staff resources applied to a design non-conformance issue correlate to the potential risk and safety significance of the issue. The staff envisions that this approach would focus first on evaluating the risk and safety significance of the non-compliance. If the issue is determined to be of low risk and low safety significance, then the staff interaction with the licensee would focus on establishing a reasonable timetable for corrective action by the licensee combined with implementing appropriate interim compensatory measures that would maintain adequate safety while the corrective action is being taken. The approach would include enforcement discretion (possibly for a long duration) to provide the licensee adequate time for implementing corrective action. This approach is envisioned to be an improvement over the current practice in that it would eliminate the need for urgent action to be taken for low risk significance compliance issues.
This approach is consistent with the NRC's Enforcement Policy (NUREG-1600, "General Statement of Policy and Procedure for NRC Enforcement Action", Section 1.5 "Adequate Protection Standard," which states:
"Adequate protection of the public health and safety and assurance of the common defense and security and protection of the environment are the NRC's fundamental regulatory objectives. Compliance with NRC requirements plays a critical role in giving the NRC confidence that safety and security are being maintained. While adequate protection is presumptively assured by compliance with NRC requirements, circumstances may arise where new information reveals that an unforeseen hazard or security issue or security event exists or that a substantially greater potential exists for a known hazard to occur. In such situations, the NRC has the statutory authority to require action by licensees, their employees and contractors, and certificate holders above and beyond existing regulations to maintain the level of protection necessary to avoid undue risk to public health and safety, and to ensure security of materials.
The NRC also has the authority to exercise discretion to permit continued operations — despite the existence of a noncompliance — where the noncompliance is not significant from a risk perspective and does not, in the particular circumstances, pose an undue risk to public health and safety. When noncompliance with NRC requirements occurs, the NRC must evaluate the degree of risk posed by that noncompliance to determine whether immediate action is required. If the NRC determines that the noncompliance itself is of such safety significance that adequate protection is no longer provided, or that the noncompliance was caused by a failure of licensee controls so significant that it calls into question the licensee's ability to ensure adequate protection, the NRC may demand immediate action, up to and including a shutdown or suspension of licensed activities. Based on the NRC's evaluation of noncompliance, the appropriate action could include refraining from taking any action, taking specific enforcement action including the use of civil penalties, issuing Orders, or providing input to other regulatory actions or assessments, such as increased NRC oversight of a licensee's activities. Since some requirements are more important to safety than others, the NRC endeavors to use a risk-informed approach when applying NRC resources to the oversight of licensed activities, including enforcement activities."
Previous Fiscal Years
FY 2015
In September 2015, a working group with members from NRR, the Regions, OGC, and OE was formed, and began evaluating the feasibility of the proposed approach, including verifying the legality of the approach determining how the risk significance would be evaluated, and gaging the industry's interest in participating in the process once developed. The working group also looked at the process for implementing this new approach. One implementation method that was considered was modifying the Notice of Enforcement Discretion (NOED) process to provide a process for addressing for low risk, low safety significance design compliance issues in a risk-informed manner.
FY 2016
Three public meetings were held to discuss this initiative. The meetings were held at NRC Headquarters on February 3, 2016, April 11, 2016, and May 23, 2016. The Commission was also briefed on the initiative during the Operating Reactor Business Line briefing on July 7, 2016. A draft outline of the proposed process was developed and circulated within NRR, the Regional Offices, OE and OGC for comment.
FY 2017 – FY 2018
After modification of the draft outline based on internal feedback, the outline was made publicly available for feedback from external stakeholders. Based on feedback received from internal and external stakeholders from the review of the draft outline for the proposed DCED process, a draft DCED procedure was developed and circulated internally for review and a draft Commission Notation Vote paper was prepared. However, the DCED Commission Paper due date was extended to October 2018 for the following reasons:
- So the staff can examine new guidance documents that are under development (e.g., backfit guidance resulting in part from Commission direction in SRM-COMSECY-16-0020 and operability guidance under development by NEI) and evaluate their potential for reducing the number of low risk and low safety significance operability issues created by non-compliances with design requirements.
- If the staff concludes that the new guidance documents are unlikely to significantly reduce the number of DCED candidate issues, the staff will explore additional options consistent with feedback received from both internal and external stakeholders. The options will seek to:
- better balance the public's hearing rights with risk-informing the agency's response to low risk, low safety significance operability issues,
- align on the extent to which technical specifications can and should be risk-informed, and
- engage more extensively with external stakeholders.
The proposed process will utilize risk insights as one of the criteria to determine if a design issue is a candidate for the licensee to request enforcement discretion under the proposed DCED process.
FY 2019
The agency was developing a risk-informed approach to resolve licensee design issues that render a technical specification structure, system or component inoperable and are determined to be of low risk/low safety significance. The goal was to provide a tool to the staff that provides a risk-informed alternative to enforcement of technical specification compliance when it can be demonstrated that the non-compliance does not pose an undue risk to public health and safety. This initiative has been sunset as several other initiatives are anticipated to reduce the number of candidate design noncompliance issues such as (1) Backfit Guidance and Training, (2) Industry Operability Initiative and revision of IMC 0326, and (3) Risk-Informed Technical Specification Initiative 4b, "Risk-Informed Completion Times." Therefore, the agency no longer sees a need for the proposed DCED process. However, agency will continue to explore resource-appropriate ways to address issues of low risk and low safety significance as opportunities arise.
FY 2020
FY 2020
The DCED activity has been sunset. For FY 2020, agency efforts to address issues of low risk and low safety significance are discussed under the LSSIR effort.
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Probabilistic Flood Hazard Assessment (PFHA)
Summary Description
The PFHA research program is a wide-ranging effort to establish a sound technical basis for transitioning flood hazard assessment guidance and tools from deterministic to probabilistic approaches. The PFHA research is guided by a joint NRO-NRR user need that endorsed a Research Plan developed jointly by RES, NRR, and NRO staff. A copy of the plan (cover sheet and final plan) was provided to the Commission in 2014. RES has been implementing the research plan since approximately 2014.
By supporting development of risk-informed licensing and oversight guidance and tools for assessing flooding hazards and consequences, this research addresses a significant gap in the probabilistic basis for external hazards since seismic and wind hazard assessments are currently conducted on a probabilistic basis. The PFHA research program is designed to support both new reactor licensing (e.g. design basis flood hazard assessments for new sites or facilities) and oversight of operating reactors (e.g. significance determination process analyses for evaluating inspection findings or event assessments involving flood hazards, flood protection, or flood mitigation at operating facilities).
Previous Fiscal Years
FY 2015
The "Probabilistic Flood Hazard Assessment Research Plan" has been prepared and endorsed by NRR and NRO. Eleven new research projects have been initiated with the US Army Corps of Engineers, the US Geological Survey, the Department of Interior Bureau of Reclamation, Idaho National Laboratory (INL), Pacific Northwest National Laboratory (PNNL), and the University of California at Davis. A twelfth research activity that was issued for bid as a commercial contract has not yet been awarded. On October 13 and 14, 2015, the first annual program review on the progress for these projects will be held at NRC headquarters. Cooperative efforts are under development with Electric Power Research Institute (EPRI) and the Institute de Sûreté Nucléaire et de Radioprotection (IRSN).
FY 2016
Thirteen research projects have been initiated via interagency agreements with the US Army Corps of Engineers, the US Geological Survey, the Bureau of Reclamation, Idaho National Laboratory (INL), and Pacific Northwest National Laboratory (PNNL). A fourteenth project is being conducted with the University of California at Davis via a cooperative research contract with USGS under authority of the Water Resources Research Act. A fifteenth research activity has been implemented as a commercial contract. Cooperative research efforts have been initiated with the Electric Power Research Institute (EPRI) under a Flooding Research Addendum to an existing NRC-EPRI MOU. A cooperative research agreement is under development with the French Institute de Sûreté Nucléaire et de Radioprotection (IRSN).
FY 2017
Progress has continued on the existing projects initiated via interagency agreements and cooperative research contracts with other agencies and commercial contracts, as reported last year. A number of technical reports have been completed. Two new projects have been initiated via interagency agreement with Oak Ridge National Laboratory. The 2nd annual program review on the progress of PFHA research projects was held on January 23-25, 2017 at NRC headquarters. Cooperative research efforts with the Electric Power Research Institute (EPRI) have continued under the Flooding Research Addendum to an existing NRC-EPRI MOU. Two technical exchanges with EPRI were held in FY 2017. The technical aspects of a cooperative research agreement with the French Institute de Sûreté Nucléaire et de Radioprotection (IRSN) were completed and the agreement is under review by IRSN and NRC management.
FY 2018
Progress has continued on the existing projects initiated via interagency agreements and cooperative research contracts with other agencies and commercial contracts, as reported last year. Two new projects have been initiated via interagency agreement with Oak Ridge National Laboratory and the U.S. Geological Survey. Research projects address probabilistic modeling for precipitation, site-scale flooding, riverine flooding, and coastal flooding, as well as reliability of flood protection features and procedures. Cooperative research efforts with the Electric Power Research Institute (EPRI) have continued under the Flooding Research Addendum to an existing NRC-EPRI MOU. Several technical exchanges with EPRI were held in FY 2018, including a paleoflood hydrology workshop hosted by EPRI and the Tennessee Valley Authority (TVA) on February 21-22, 2018. A cooperative research agreement with the French Institute de Sûreté Nucléaire et de Radioprotection (IRSN) was completed and a NRC/IRSN technical exchange was held on March 26-27, 2018. The 3rd annual program review on the progress of PFHA research projects was held as a public meeting on December 4-5, 2017 at NRC headquarters. NRC staff also participated in an international workshop on riverine flooding organized by the Nuclear Energy Agency of the Organization for Economic Cooperation and Development (OECD/NEA) on March 21-23, 2018.
This activity is risk-informed because it addresses several aspects of risk: (1) probability or frequency of occurrence for various flooding scenarios; (2) fragility of flood protection features; and (3) reliability of flood protection and mitigation procedures.
FY 2019
Progress on existing projects initiated via interagency agreements and cooperative research initiatives with other agencies has continued in FY 2019 and several projects have been completed. The technical-basis-phase of the PFHA research is now largely complete. This research has comprised projects focused on specific technical details of probabilistic modeling for precipitation, site-scale flooding, riverine flooding, and coastal flooding, as well as reliability of flood protection features and procedures. The next phase (pilot projects), focused on integrating the technical basis research into holistic multi-mechanism flooding hazard assessments, was initiated in FY 2019. This phase comprises three new projects: (1) Local Intense Precipitation Flooding PFHA Pilot Study; (2) Riverine Flooding PFHA Pilot Study; and (3) Coastal Flooding PFHA Pilot Study. Cooperative research efforts with the Electric Power Research Institute (EPRI) have continued under the Flooding Research Addendum to an existing NRC-EPRI MOU. The 4th Annual NRC PFHA Research Workshop, held as a public meeting on April 30-May 2, 2019, at NRC headquarters, reviewed progress on NRC-funded projects and updated participants on PFHA research at other agencies. NRC staff participated in a three-day technical exchange with the French Institute de Sûreté Nucléaire et de Radioprotection (IRSN) at IRSN Headquarters in Paris on September 23-25, 2019. This activity is risk-informed because it addresses several aspects of risk: (1) probability or frequency of occurrence for various flooding scenarios; (2) fragility of flood protection features; and (3) reliability of flood protection and mitigation procedures.
FY 2020
FY 2020
Progress on existing projects initiated via interagency agreements and cooperative research initiatives with other agencies has continued in FY2020 and several projects have been completed. The first phase of the PFHA research (technical basis) is largely complete. This research has comprised projects focused on specific technical details of probabilistic modeling for precipitation, site-scale flooding, riverine flooding, and coastal flooding, as well as reliability of flood protection features and procedures. The second phase (pilot projects), focused on integrating the technical basis research into holistic multi-mechanism flooding hazard assessments, initiated in FY2019, is making good progress. This phase comprises three projects: (1) Local Intense Precipitation Flooding PFHA Pilot Study; (2) Riverine Flooding PFHA Pilot Study; and (3) Coastal Flooding PFHA Pilot Study. The third and final phase (guidance development), initiated in FY2020, is at the scoping stage. Proceedings from the first four Annual PFHA Research Workshops was published as an NRC Research Information Letter (RIL-2020-01). The 5th Annual NRC PFHA Research Workshop, held as a public meeting on February 19-21, 2020 at NRC headquarters, reviewed progress on NRC-funded projects and updated participants on PFHA research at other agencies. NRC staff participated in a 3-day technical exchange with the French Institute de Sûreté Nucléaire et de Radioprotection (IRSN) at IRSN Headquarters in Paris on Sept 23-25, 2019. Cooperative research efforts with the Electric Power Research Institute (EPRI) and the French Institute de Sûreté Nucléaire et de Radioprotection (IRSN) have continued under existing agreements.
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Risk Assessment of Operation Events (RASP Handbook)
Summary Description
Provide methods and guidance for the risk-informed analysis of operational events and licensee performance issues including internal and external events during both full power and low-power/shutdown operations.
Risk-Informed analyses are performed in response to needs identified in: Management Directive 8.3, "Incident Investigation Program"; Reactor Oversight Process; the Significance Determination Process (SDP); and the Accident Sequence Precursor (ASP) program. State-of-the-practice methods and guidance support risk analysts and senior reactor analysts from various NRC offices (NRR, RES, NRO, and the Regions) that use risk analysis software (SAPHIRE) and plant-specific PRA model (SPAR models).
The Risk Assessment Standardization Project (RASP) handbook and associated internal web site provides guidance and a description of the methods the NRC staff uses to achieve consistent results in the performance of risk-informed studies of operational events and licensee performance issues. It is updated periodically based on user comments and insights gained from field application. The handbook consists of four volumes, designed to address internal events analysis, external events analysis, Standardized Plant Assessment Risk (SPAR) model reviews, and shutdown event analysis. The handbook incorporates best practices gleaned from experience on accident precursor events performed in ASP reviews and other insights gained from SDP analyses.
Previous Fiscal Years
FY 2015
This activity continually provides support to risk analysts and routinely updates the RASP Handbook and the associated Web site to assure accuracy and provide additional references for risk analysts' use.
FY 2016
The staff prepared for the publication of a NUREG on the application of Common Cause Failure (CCF) Analysis in Event and Condition Assessment. The intent of this report is to provide acceptable methods that the staff will accept in the area of CCF when applied to identified component and system failures which typically occur as part of SDP and ASP evaluations.
FY 2017
The staff revised the RASP handbook volume on internal events that provides additional guidance on how to credit alternate mitigating strategies (e.g., FLEX) in risk assessments. These mitigating strategies employ plant responses which utilize portable equipment to restore or maintain various safety functions during beyond design basis conditions and the loss of permanently installed plant equipment.
The staff also revised the RASP Handbook volume on external events that provides methods and guidance on evaluating risk associated with external flooding and seismic. For external flooding, this update uses lessons learned from the analyses of approximately 10 "greater-than-green" findings relating to external flooding that resulted from inspections conducted after the events at Fukushima Dai-Ichi. The revised guidance provides references to methods and datasets along with discussion of common issues with external flooding assessments. For seismic, this revision incorporates updated site-specific seismic information based on licensees' recent seismic hazard reevaluations addressing Near-Term Task Force Recommendation 2.1. The revised guidance also provides references to methods that address key aspects required by the American Society of Mechanical Engineers/American Nuclear Society PRA Standard for a seismic PRA.
FY 2018
The staff published NUREG-2225, "Basis for the Treatment of Potential Common Cause Failure in the Significance Determination Process." It describes the basic assumptions and key principles for treating CCF of redundant components in SDP risk assessments when one or more of the redundant components are failed or functionally degraded due to a deficiency in licensee performance. The staff also prepared guidance on estimating the risk metric of Large Early Release Frequency (LERF) from a consequential steam generator tube rupture (C-SGTR) event.
This activity helps to put a risk perspective on operational events and inspection findings. It is not always obvious how much actual risk is associated with identified violations or component/system failures. This activity attempts to take advantage of insights gained using PRA modeling as applied to operational events discovered during normal operations, which have the potential to contribute to nuclear plant risk. As such, it provides a different and independent perspective on nuclear plant performance than would be available simply by tracking compliance with plant technical specifications and operational directives.
FY 2019
The staff did not make any changes to the RASP handbook during FY 2019.
FY 2020
FY 2020
The staff did not make any changes to the RASP Handbook in FY2020.
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Maintenance and Development of the Systems Analysis Programs for Hands-on Analysis Integrated Reliability Evaluations (SAPHIRE) Code
Summary Description
The NRC has developed and maintains the SAPHIRE computer code for performing probabilistic risk analyses (PRAs). SAPHIRE offers state-of-the-art capability for assessing the risk associated with core damage frequency (Level 1 PRA) and the risk from containment performance and radioactive releases (Level 2 PRA). SAPHIRE supports the agency's risk-informed activities, which include the Standardized Plant Analysis Risk (SPAR) model development plan, the risk assessment standardization project, the Significance Determination Process (SDP), Accident Sequence Precursor (ASP) program, risk-informing 10 CFR Part 50, vulnerability assessment, advanced reactor assessment, operational experience, generic issues, and regulatory backfit.
Previous Fiscal Years
FY 2015
A summary of recent activities regarding the status of the SAPHIRE computer code can be found in SECY 15-0124, "Status of the Accident Sequence Precursor Program and the Standardized Plant Analysis Risk Models."
FY 2016
The SAPHIRE development team continues to maintain the code's performance and add new features in accordance with the SAPHIRE software quality assurance program. During FY 2016 two new SAPHIRE versions were released for use by NRC staff. Improvements include enhanced seismic hazard modeling capability and development of a new quantification approach with improved accuracy for models involving high failure probabilities.
FY 2017
The SAPHIRE development team released one new version of the SAPHIRE software during FY 2017. A number of improvements were made to the reporting capabilities and user options. In addition, the number of modeled accident sequences that SAPHIRE can store was increased from 2,000,000 to 4,500,000, which was necessary as the size and complexity of models continues to grow. The new version release coincided with a significant update to all the SPAR models. The SAPHIRE team performed extensive testing with the new SAPHIRE version to identify and resolve any issues prior to releasing the updated models. The SAPHIRE development team continues to maintain the code's performance and add new features in accordance with the SAPHIRE software quality assurance program.
FY 2018
The SAPHIRE development team continues to make software improvements in accordance with the software quality assurance program, which is described in NUREG/CR-7039, Volume 6, "SAPHIRE Version 8: Quality Assurance." The SAPHIRE development team released three new versions of the SAPHIRE software during FY 2018. A significant new feature that has been added to the code is the ability to load pre-defined groups of model changes (referred to as "change sets") into an event or condition assessment. This feature makes it easier for analysts to perform different what-if scenarios to assess the impacts of changes in modeling assumptions or reliability data input. Another important new code feature allows users to directly post their analyses to a centralized and secure web portal. This enhances the NRC staff's abilities for sharing information and collaboration, which is particularly helpful when staff are collaborating across the Regional Offices, Headquarters, and contractors at the Idaho National Laboratory.
The SAPHIRE computer code is used to develop and run PRA models (e.g., SPAR models) for a variety of risk-informed regulatory applications.
FY 2019
The SAPHIRE development team continues to make software improvements in accordance with the software quality assurance program, which is described in NUREG/CR-7039, Volume 6, "SAPHIRE Version 8: Quality Assurance." The SAPHIRE development team released the latest version of SAPHIRE, version 8.2.0, in August 2019. A significant improvement that supports the use of this risk tool was the introduction of a cloud-based platform to access SAPHIRE and the SPAR models. This cloud-based platform is hosted on the Idaho National Laboratory Safety Portal. The use of the INL Safety Portal support future development of a cloud-based version of SAPHIRE that is anticipated to become available in the near future. These advances enhance the NRC staff's abilities for sharing information and collaboration, which is particularly helpful when staff are collaborating across the Regional Offices, Headquarters, and contractors at the Idaho National Laboratory. The SAPHIRE computer code is used to develop and run PRA models (e.g., SPAR models) for a variety of risk-informed regulatory applications.
FY 2020
FY 2020
The SAPHIRE development team continues to make software improvements in accordance with the software quality assurance program, which is described in NUREG/CR-7039, Volume 6, "SAPHIRE Version 8: Quality Assurance." The SAPHIRE development team released the latest version of SAPHIRE, version 8.2.2, in June 2020. One focus area for the team has been the development of a cloud-based solving platform. With PRA models increasing in scope and complexity, the SAPHIRE team is working to leverage the significant computing resources available on the computer cluster hosted by NRC's contractors at the Idaho National Laboratory. The latest release of SAPHIRE takes a step toward achieving that goal by including the capability to send the model logic to an external solving engine. Although additional development is needed before users can access the cloud-based solving platform, it marks an important development milestone. Beyond the cloud-based development, the SAPHIRE team continues to respond to users' requests for new features and address any identified code errors. The SAPHIRE team has also begun work to develop new features to streamline updates to the model database, which will allow for a more efficient process for keeping the reliability data up-to-date across the entire suite of SPAR models.
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Standardized Plant Analysis Risk Models (SPAR)
Summary Description
The SPAR models provide agency risk analysts with an independent risk assessment tool to support a variety of risk-informed agency programs, including the Reactor Oversight Program (ROP) and the Accident Sequence Precursor (ASP) program. SPAR models are built with a standard modeling approach, using consistent modeling conventions, that enables staff to easily use the models across a variety of U.S. Nuclear Power Plant (NPP) designs. Unlike industry PRA models, SPAR models are run on a single software platform, the Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) computer code. The staff currently maintains and updates the 75 SPAR models representing 99 commercial NPPs. The scope of every SPAR model includes logic modeling covering internal initiating events at power through core damage (i.e., Level-1 PRA model). A portion of the SPAR models also include external hazard (e.g., seismic and high wind), internal fire, and shutdown models.) The staff develops and maintains SPAR models for both operating reactors and new reactor designs (e.g., AP1000).
Previous Fiscal Years
FY 2015
An updated status of the SPAR model program can be found in SECY 15-0124, "Status of the Accident Sequence Precursor Program and the Standardized Plant Analysis Risk Models."
FY 2016
The staff continued to develop new SPAR model capabilities and provide technical support for SPAR model users and risk-informed programs. The staff maintains and implements a quality assurance (QA) plan for the SPAR models to ensure that the models appropriately represent the as-built, as-operated nuclear plants to support the assessment of operational events within the staff's risk-informed regulatory activities. The SPAR QA Plan provides mechanisms for model benchmarking and reviews, validation and verification, and configuration control of the SPAR models. In addition, about half of the SPAR models are updated to reflect significant plant modifications or other plant or modeling changes.
The staff also continued developing the SPAR model for the AP1000 new reactor design, adding a low power shut down model and a level 2 PRA model for the AP1000 reactor design.
FY 2017
The staff continued to maintain all SPAR models, with the implementation of the QA plan to represent the as built-as operated nuclear plants; and continued to provide technical support for SPAR model users and risk-informed programs. During FY 2017, the staff updated all SPAR models to reflect the most recent plant reliability data. For new reactor designs, the staff continued to work on expanding the AP1000 SPAR model capabilities (e.g., shutdown and Level 2 model); and initiated work on plant specific SPAR models for Vogtle (AP1000).
FY 2018
During FY 2018 the staff continued to maintain and improve SPAR models to reflect the as-built-as operated nuclear power plants and continued to provide technical support for SPAR model users and risk-informed programs. In an effort to meet the objective or reflecting the as-built-as-operated plant, about 80 percent of the SPAR models were modified. These modifications included: routine updates to reflect recent plant changes, modifications to the models to reflect new Westinghouse Gen 3 seals, and SPAR model modifications to incorporate FLEX modeling. For new reactor designs, the staff continued the efforts to collect information to start building the plant specific PRA model for Vogtle Units 3 & 4 (AP1000).
The SPAR models are used by NRC staff in support of risk-informed activities related to the inspection program, incident investigation program, license amendment reviews, performance indicator verification, accident sequence precursor program, generic safety issues, and special studies. These models also support and provide rigorous and peer reviewed evaluations of operating experience, thereby demonstrating the agency's ability to analyze operating experience independently of licensees' risk assessments and enhancing the technical credibility of the agency.
FY 2019
During FY 2019 the staff continued to maintain and improve SPAR models to reflect the as-built-as operated nuclear power plants and continued to provide technical support for SPAR model users and risk-informed programs. In an effort to meet the objective or reflecting the as-built-as-operated plant, a total of 226 SPAR model modifications were completed. These modifications included: routine updates to reflect recent plant changes, incorporation of new logic associated with external events, SPAR model modifications to incorporate FLEX modeling, and modifications to support Significance Determination Process (SDP) or Events and Conditions Assessment (ECA) analyses. For new reactor designs, the staff continued the initial process of gathering information to develop the plant specific PRA model for Vogtle Units 3 & 4 (AP1000).
The SPAR models are used by NRC staff in support of risk-informed activities related to the inspection program, incident investigation program, license amendment reviews, performance indicator verification, accident sequence precursor program, generic safety issues, and special studies. These models also support and provide rigorous and peer reviewed evaluations of operating experience, thereby demonstrating the agency's ability to analyze operating experience independently of licensees' risk assessments and enhancing the technical credibility of the agency.
FY 2020
FY 2020
During FY 2020 the staff continued to maintain and improve SPAR models to reflect the as-built-as operated nuclear power plants and continued to provide technical support for SPAR model users and risk-informed programs. In an effort to meet the objective or reflecting the as-built-as-operated plant, a total of 150 SPAR model formal modifications were completed. These modifications included: routine updates to reflect recent plant changes, incorporation of new logic associated with external events, SPAR model modifications to incorporate FLEX modeling, and modifications to support the Significance Determination Process (SDP) or Events and Conditions Assessment (ECA) analyses. For new reactor designs, the staff initiated the development of the internal events plant specific PRA model for Vogtle Units 3 & 4 (AP1000).
The SPAR models are used by NRC staff in support of risk-informed activities related to the inspection program, incident investigation program, license amendment reviews, performance indicator verification, accident sequence precursor program, generic safety issues, and special studies. These models also support and provide rigorous and peer reviewed evaluations of operating experience, thereby demonstrating the agency's ability to analyze operating experience independently of licensees' risk assessments and enhancing the technical credibility of the agency.
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Full-Scope Site Level 3 PRA
Summary Description
As directed in SRM-SECY-11-0089, "Options for Proceeding with Future Level 3 Probabilistic Risk Assessment (PRA) Activities," the staff is conducting a full-scope multi-unit site Level 3 PRA that addresses all internal and external hazards; all plant operating modes; and all reactor units, spent fuel pools, and dry cask storage.
The full-scope site Level 3 PRA project includes the following objectives:
- Develop a Level 3 PRA, generally based on current state-of-practice methods, tools, and data, that (1) reflects technical advances since completion of the NUREG-1150 studies, and (2) addresses scope considerations that were not previously considered (e.g., low power and shutdown, multi-unit risk, and spent fuel storage).
- Extract new risk insights to enhance regulatory decision making and help focus limited agency resources on issues most directly related to the agency's mission to protect public health and safety and the environment.
- Enhance PRA staff capability and expertise and improve documentation practices to make PRA information more accessible, retrievable, and understandable.
- Obtain insight into the technical feasibility and cost of developing new Level 3 PRAs.
Consistent with the objectives of this project, the Level 3 PRA study is based on current state of-practice methods, tools, and data. However, there are several gaps in current PRA technology and other challenges that require advancement in the PRA state-of-practice. The general approach to addressing these challenges for the Level 3 PRA study is to primarily rely on existing research and the collective expertise of the NRC's senior technical advisors and contractors, and to perform limited new research only for a few specific technical areas (e.g., multi-unit risk).
Based on a set of site selection criteria and with the support of the NEI, a reference site was selected for the Level 3 PRA study. The reference site contains two four-loop Westinghouse PWRs with large dry containments. The Level 3 PRA project team is leveraging the existing and available information on the reference site and the corresponding licensee PRAs, in addition to related research efforts (e.g., SOARCA), to enhance efficiency in performing the study.
The Level 3 PRA project team is using the following NRC tools and models for performing the Level 3 PRA study:
- SAPHIRE, Version 8.
- MELCORE Severe Accident Analysis Code.
- MELCOR Accident Consequence Code System, Version 2 (MACCS).
In addition, the Level 3 PRA study is being developed consistent with many of the modeling conventions used for NRC's SPAR models.
Previous Fiscal Years
FY 2015
A PWR Owners Group (PWROG)-led ASME/ANS PRA Standard-based peer review of the reactor, at-power, high wind, Level 1 PRA and a screening evaluation of reactor, at-power "other" hazards (i.e., hazards other than internal events, internal floods, internal fires, high winds, and seismic events) was performed in November 2014. A PWROG-led ASME/ANS PRA Standard-based peer review of the reactor, at-power, internal event and internal flood Level 2 PRA was performed in December 2014. A PWROG-led workshop was held in January 2015 to identify peer review criteria for dry cask storage PRA. An expert elicitation was completed in June 2015 to address the frequency of interfacing systems LOCAs. The reactor, at-power, internal event and internal flood Level 3 PRA was completed in August 2015. Initial versions of reactor, at-power, Level 1 PRA models for internal fires and seismic events were completed in FY 2015, but they need to be significantly revised to incorporate more recent licensee-supplied information.
FY 2016
A PWROG-led ASME/ANS PRA Standard-based peer review of the reactor, at-power, internal event and internal flood Level 3 PRA was performed in October 2015. A substantial revision was completed for the reactor, at-power, Level 1 PRAs for internal events and internal floods. The reactor, at-power, Level 1 PRAs for internal fires and seismic events were significantly revised to incorporate more recent licensee-supplied information. The dry cask storage (DCS) PRA was completed for all PRA levels and all hazards, and reviewed internally. In response to review comments, the consequence analysis for the DCS PRA will be revised. Substantial progress was made on an initial reactor, low power and shutdown (LPSD), Level 1 PRA for internal events. An approach was developed for modeling integrated site risk and a pilot application of this approach was performed based on the results of the revised Level 1 PRAs for internal events for Units 1 and 2 of the reference plant.
FY 2017
The final report was completed for the revised reactor, at-power, Level 1 PRA for internal events. A substantial revision was completed for the reactor, at-power, Level 2 PRA for internal events and internal floods. Significant progress was made on a substantial revision to the reactor, at-power, Level 3 PRA for internal events and internal floods. Internal technical reviews were completed on the reactor, at-power, Level 1 PRAs for internal fires and seismic events. Substantial revisions were completed for the reactor, at-power, Level 1 PRA for high winds and the qualitative screening analyses for other hazards. The DCS PRA for all PRA levels and all hazards was revised. The initial reactor, (LPSD), Level 1 PRA for internal events was completed. Two-unit pilot applications of the integrated site risk approach were completed for the Level 2 PRA for internal events, the Level 1 PRA for seismic events, and the Level 1 PRA for LPSD (one unit in operation, and one unit in shutdown).
FY 2018
Final reports were completed for the revised reactor, at-power, Level 1 PRAs for internal floods and high winds; revised reactor, at-power, Level 2 PRA for internal events and floods; and revised qualitative screening analyses for other hazards. The reactor, at-power, Level 1 PRA for internal fires was submitted to the Level 3 PRA Technical Advisory Group (TAG) for review. The reactor, LPSD, Level 1 PRA for internal events was also submitted to the Level 3 PRA TAG for review. Substantial work was completed on the reactor, at-power, Level 2 PRA for internal fires, seismic events, and high winds; the reactor, LPSD, Level 2 PRA for internal events; and the spent fuel pool Level 1 and Level 2 PRAs (all hazards).
FY 2019
The technical work on the Level 3 PRA Project is nearing completion, with a target date for release of the results in FY 2022. Internal reports on the reactor, at-power, Levels 1, 2, and 3 PRAs for internal events and floods; the reactor, at-power, Level 1 PRA for high winds; and the screening analysis of other hazards are essentially complete. The reactor, at-power, Level 1 PRAs for internal fires, seismic events, and low power and shutdown are nearing completion. Substantial work has been completed on the reactor, at-power, Level 2 PRAs for internal fires, seismic events, and high winds; the reactor, LPSD, Level 2 PRA for internal events; and the spent fuel pool Level 1 and Level 2 PRAs (all hazards). Work on the Level 3 PRAs for reactor, at-power internal fires, seismic events, and high winds continues, as does the work on the Level 1, 2, and 3 Dry Cask Storage PRA. Pilot activities have been completed to demonstrate the proposed approach for integrated site risk using a dual-unit model. The pilot activities included Level 1 and 2 PRAs for internal events and floods, Level 1 PRAs for internal fires and seismic events, and a Level 1 PRA for internal events with one unit operating and one unit shut down. With the pilot activities complete, work has been initiated on the reactor, at-power, Level 1, 2, and 3 dual-unit PRA models for internal events and floods.
FY 2020
FY 2020
The technical work on the Level 3 PRA Project is nearing completion, with a target date for release of the results in FY22. Internal reports on the reactor, at-power, Levels 1, 2, and 3 PRAs for internal events and floods; the reactor, at-power, Level 1 PRAs for internal fires, seismic events, and high winds; and the screening analysis of other hazards are complete. The reactor, at-power, Level 1 PRA low power and shutdown (internal events only) is nearing completion. Substantial work has been completed on the reactor, at-power, Level 2 and 3 PRAs for internal fires, seismic events, and high winds; the reactor, LPSD, Level 2 PRA for internal events; and the spent fuel pool Level 1 and Level 2 PRAs (all hazards). Work is continuing on the Level 3 PRAs for the reactor, LPSD, for internal events and the spent fuel pool, as well as on the Level 1, 2, and 3 Dry Cask Storage PRA. Pilot activities have been completed to demonstrate the proposed approach for integrated site risk using a dual-unit model. The pilot activities included Level 1 and 2 PRAs for internal events and floods, Level 1 PRAs for internal fires and seismic events, and a Level 1 PRA for internal events with one unit operating and one unit shut down. With the pilot activities complete, work has been initiated on the reactor, at-power, Level 1, 2, and 3 dual-unit PRA models for internal events and floods.
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Data Collection for Human Reliability Analysis (HRA)
Summary Description
Consistent with the Commission's policy statements on the use of probabilistic risk assessment (PRA) and for achieving an appropriate PRA quality for NRC risk-informed regulatory decision-making, the NRC has ongoing activities to improve the quality of human reliability analysis (HRA). The adequacy of data available for HRA is a concern on the credibility and consistency of human error probability estimates. To address this need, NRC's Office of Nuclear Regulatory Research (RES) has developed the Scenario Authoring, Characterization, and Debriefing Application (SACADA) system to collect operator performance information in simulator exercises. RES has collaborated with nuclear power plants and research institutes to use the SACADA system to collect their simulator training, examination, and experiment data. In addition, RES reviews literature and operations experience, and plans to collaborate with nuclear power plants to collect the human performance information of actions performed outside of the main control room.
Previous Fiscal Years
FY 2015
The key near term SACADA research activities include:
- Analyzing the collected data to inform human reliability and human performance. This includes demonstrating the use of the data to inform human error probability (HEP) calculations in HRA.
- Collaborating with more data providers to increase the size of the data pool.
FY 2016
The following two SACADA collaborations were established in FY 2016:
- The Taiwan Power Company (TPC): To support this agreement, RES, with support of TPC, developed a Chinese version of SACADA for TPC plants to use. RES, with the support of the South Texas Project Nuclear Operating Company and the Idaho National Laboratory, provided SACADA training to the TPC instructors. TPC is piloting the SACADA system.
- The Advanced Test Reactor (ATR) of the Department of Energy: The ATR has used the SACADA system and has made data accessible to the NRC since June 2016.
FY 2017
The following are tasks accomplished in FY 2017:
- Established an agreement with the Grand Gulf Nuclear Generating Station to use the NRC's SACADA system to collect the licensed operator performance information in simulator training and to share the information with the NRC for improving HRA techniques.
- Awarded two contracts to perform independent analysis of the SACADA data for HRA. The results will be presented at a NRC-hosted HRA data workshop on March 15 and 16, 2018 at the NRC headquarters.
The following are activities are either in process or performed:
- Establishing an agreement for the Vogtle Unit 3 and Unit 4 site to use the NRC's SACADA system for operator simulator training. After the operators are licensed, the performance data will be shared with the NRC to improve HRA techniques.
- Performing literature and operations experience review to inform human performance assessment of FLEX strategy implementation.
- Plan to host a SACADA data workshop in March 2018 to discuss SACADA data analysis results and improvements.
- In negotiation with Entergy to collaborate on expanding the SACADA scope to collect operator performance in simulator training, on the job training, written tests, and actual events.
- Continue outreach to NRC licensees on using SACADA for operator simulator training.
FY 2018
The following are the accomplishments and ongoing tasks in FY 2018:
- Established an agreement with Vogtle Unit 3 and Unit 4 sites to use the NRC's SACADA system for operator simulator training.
- Hosted an international HRA Data workshop on March 15 and 16, 2018 at the NRC Headquarters featuring:
- 40 participants from 23 organizations of seven countries
- Presentations from three NRC contractors with proposals for using SACADA data for human error probability estimations
- Nine technical presentations from workshop participants
- Workshop documentation via 2018 March 15&16 Human Reliability Analysis Data Workshop
- Presented recent SACADA research results at the SACADA Data technical session at the 14th Probabilistic Safety Assessment and Management (PSAM 14) conference (www.PSAM14.org), September 16-21, 2018.
- Developing a revision to SACADA software to collect operator performance in simulator training, job performance measures, written exams, and actual events (with technical support provided by South Texas Project and Vogtle 3&4 instructors).
- Continuing outreach to NRC licensees and the international nuclear industry on using SACADA for operator simulator training.
Human reliability analysis results are used in the NRC's risk-informed regulatory activities such as the reactor oversight process. The collected data would improve the reliability of NRC's HRA methods. That, in turn, improves the reliability of the NRC's risk-informed decision-making.
FY 2019
The following are the accomplishments and ongoing tasks in FY 2019:
- Renewed a memorandum of understanding with the Korea Atomic Energy Research Institute on HRA Data Collaboration, effective until November 2024.
- Hosted an international HRA Data workshop on March 14 and 15, 2019 at the NRC Headquarters featuring:
- Continuing outreach to NRC licensees and the international nuclear industry on using SACADA for operator simulator training.
Human reliability analysis results are used in the NRC's risk-informed regulatory activities such as the reactor oversight process. The collected data would improve the reliability of NRC's HRA methods. That, in turn, improves the reliability of the NRC's risk-informed decision-making.
FY 2020
FY 2020
RES expanded SACADA's capability to collect operator performance in job performance measures (JPMs). RES continues outreach to nuclear power plants to use SACADA to collect JPM performance information. Also, RES reviews literature and operational experience, and plans to collaborate with nuclear power plants to collect the human performance information related to the operations of nuclear facilities and document the information in the IDHEAS-DATA report (draft, ADAMS Accession Number: ML20238B982). RES has collaborated with domestic and international organizations to use simulator data to inform HRA.
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Human Reliability Analysis (HRA) Methods and Practices
Summary Description
The purpose of the HRA method effort is to improve the methods for regulatory applications. This enhancement involves improving the consistency amongst HRA practitioners in the use of methods and developing guidance on the rigor needed for quantifying human reliability given the scarcity of empirical data available to evaluate human performance. The ongoing activities include:
- Developing the Integrated Human Event Analysis System (IDHEAS) for risk analyses of all nuclear-related HRA applications (SRM-M061020)
- Developing IDHEAS application for event and condition analysis (IDHEAS-ECA)
Regulatory Guide (RG) 1.200 provides an acceptable approach for determining the technical adequacy of probabilistic risk assessment (PRA) results for risk-informed regulation. HRA is a key element in the PRA. Because various HRA methods often have different assumptions and approximations that could lead to significant variability in results affecting regulatory decisions, enhancing the consistency and quality of HRA could improve regulatory decision-making.
Previous Fiscal Years
FY 2015
The report "Cognitive Basis for HRA" is finalized and will be published in 2015. The staff has been working with the ACRS Reliability and PRA Subcommittee to construct the IDHEAS General Methodology so that it can be implemented in various NPP applications. The IDHEAS internal, at-power application is currently being tested.
NUREG-2114, "Cognitive Basis for HRA" was finalized and published.
FY 2016
The following are tasks accomplished in FY 2016:
- Published NUREG-2199, Vol.1, "An Integrated Human Event Analysis System (IDHEAS) for Nuclear Power Plant Internal Events At-Power Application".
- Completed the testing of IDHEAS for internal at-power applications.
- Published NUREG-2156, "The U.S. HRA Empirical Study – Assessment of HRA Method Performances against Operating Crew Performance on a U.S. Nuclear Power Plant Simulator".
- Published NUREG-2180, "Determining the Effectiveness, Limitations, and Operator Response for Very Early Warning Fire Detector Systems in Nuclear Facilities (DELORES-VEWFIRE).
FY 2017
The following are tasks accomplished in FY 2017:
- Published NUREG-2170, "A Risk-informed Approach to Understanding Human Error in Radiation Therapy"
- The staff worked with the Electric Power Research Institute (EPRI) to develop an approach to perform HRA related to main control room abandonment in fire events and published NUREG-1921, Supplement 1, "EPRI/NRC-RES Fire Human Reliability Analysis Guidelines: Qualitative Analysis for Main Control Room Abandonment Scenarios"
The following are activities are in process:
- Completing the IDHEAS framework for risk analyses of all nuclear-related HRA applications.
- Developing the IDHEAS application for event and condition analysis to support the NRC's inspection, licensing, and enforcement activities.
- Working with the Electric Power Research Institute to develop an approach to perform HRA related to main control room abandonment in fire events:
- In publication: NUREG-1921, Supplement 1, "EPRI/NRC-RES Fire Human Reliability Analysis Guidelines: Qualitative Analysis for Main Control Room Abandonment Scenarios"
- Completing development of NUREG-1921, Supplement 2, "EPRI/NRC-RES Fire Human Reliability Analysis Guidelines: HRA Quantification for Main Control Room Abandonment Scenarios"
FY 2018
The following tasks were accomplished in FY 2018:
- Tested IDHEAS At-Power Application method in collaboration with EPRI, including:
- An evaluation of whether the method guidance could be practically applied to produce consistent HRA results, thereby improving HRA quality for risk-informed applications
- There were three pressurized water reactor (PWR) scenarios:
- Two scenarios were adapted from the U.S. Scenario 1 described a standard steam generator tube rupture (SGTR), and Scenario 2 described a total loss of feedwater (LOFW) with a misleading indicator of flow to the steam generators.
- The third scenario was developed from an actual event in which an electrical fire caused a reactor trip and subsequent loss of reactor coolant pump (RCP) seal injection and cooling.
- Overall, the results of the testing indicate that the IDHEAS At-Power method:
- provides a structured analysis framework and traceable quantification approach to HRA
- had some instances where the method was not applied consistently with method guidance
- exhibited the ability to capture a broad range of failure modes, contextual conditions, and influences on behavior associated with the difficult operator actions and complex scenarios in the study
- has the capability to translate qualitative findings into reasonable HEPs.
- Documentation of the results and lessons learned from the testing in NUREG-2199, Vol.3. (to be published)
The following are activities are in process in FY 2018:
- Working with the Electric Power Research Institute to develop an approach to perform HRA related to main control room abandonment in fire events in order to improve fire PRA realism in risk-informed applications:
- Development of NUREG-1921, Supplement 2, "EPRI/NRC-RES Fire Human Reliability Analysis Guidelines: HRA Quantification for Main Control Room Abandonment Scenarios" which addresses:
- Operator actions taken before abandonment
- Operator decision to abandon for both loss of habitability and loss of control scenarios
- Operator actions taken after abandonment (including command and control contributions to operator failure)
- Presentation to the ACRS PRA Subcommittee and peer review
- Final report documenting the guidance (to be published in 2019)
- In order to support risk-informed license amendment requests (LARs), notice of enforcement discretion (NOED) evaluations, event evaluations, and significance determination process (SDP) evaluations, the NRC staff needs an HRA method suitable for the unique FLEX context. This method will enable the staff to assign human error probabilities (HEPs) for such actions and incorporate the associated human failure events (HFEs) in the NRC's SPAR models. Research activities in 2018 include:
- Development of the IDHEAS application for event and condition analysis to support the NRC's inspection, licensing, and enforcement activities.
- Development of a simplified HRA tool that can be used to quantify the HEPs of human actions in FLEX strategies
- Performance of an expert elicitation to develop human error probabilities with the following results:
- Identification of the unique performance shaping factors associated with the use of FLEX equipment,
- evaluation of the contribution of the these performance shaping factors on HEPs, and
- development of HEPs associated with a few typical strategies for using FLEX equipment for added defense in depth during non-FLEX-designed accident scenarios and during FLEX-type scenarios (such as transportation, placement, connection, and local control of portable pumps and generators, refilling water storage tanks using alternate water sources, declaration of ELAP, and deep DC load shedding)
- Drafting a NUREG report documenting the expert elicitation process and results (to be published in FY2019.
The purpose of the HRA method efforts is to improve the methods to be used for regulatory applications and the consistency among HRA practitioners in performing HRA. This will help improve HRA/PRA quality and provide a basis for risk-informed regulatory actions.
FY 2019
The following tasks were accomplished in FY 2019:
- Completed the development of the Draft IDHEAS General Methodology (IDHEAS-G):
- Developed a new function of IDHEAS-G to generalize and integrate human error data of various sources to calculate human error probabilities (HEPs)
- Made the Draft IDHEAS-G report publicly available
- Presented IDHEAS-G to ACRS Subcommittee on 9/18/2019
- Completed the development of the Draft IDHEAS Events and Conditions Assessment Method (IDHEAS-ECA):
- IDHEAS-ECA is a human reliability analysis (HRA) method that is based on the General Methodology of an Integrated Human Event Analysis System (IDHEAS-G). The method is intended to be used in event and condition assessment (ECA) of nuclear power plants.
- IDHEAS-ECA supports probabilistic risk assessment (PRA) applications by analyzing human events and estimating human error probabilities. The application scope of IDHEAS-ECA is broad because the performance-influencing factor (PIF) structure, which models the context of a human failure event (HFE), is comprehensive. The method covers all the PIFs in existing HRA methods and the factors reported in broad literature and in nuclear-specific human events. Because of the comprehensiveness of the PIF structure, IDHEAS-ECA can model the context of HFEs inside and outside an NPP control room—including the use of flexible and coping strategies (FLEX) equipment—and during different plant operating states (i.e., at-power and shutdown). IDHEAS-ECA can be used in PRA applications; for example, the significance determination process (SDP), accident sequence precursor (ASP) program, and risk-informed licensing reviews.
- To facilitate the use of IDHEAS-ECA, the NRC staff developed the IDHEAS-ECA Software tool to calculate the HEPs of HFEs analyzed in the IDHEAS-ECA process.
- The IDHEAS-ECA Software has been evaluated by NRR users, tested by the development team, and approved by the NRC Information Technology for installation on NRC computers.
- A draft Users' Manual and training materials on IDHEAS-ECA were developed. The development team administrated two training session to NRC and industry PRA/HRA analysts that will use IDHEAS-ECA to perform HRA of human actions in FLEX Strategies.
- The following are activities in progress:
- Working with the industry to analyze human actions in FLEX Strategies using the IDHEAS-ECA method:
- In order to support risk-informed license amendment requests (LARs), notice of enforcement discretion (NOED) evaluations, event evaluations, and significance determination process (SDP) evaluations, the NRC staff needs an HRA method suitable for the FLEX context. IDHEAS-ECA enables the staff to assign human error probabilities (HEPs) for such actions and incorporate the associated human failure events (HFEs) in the NRC's SPAR models.
- In this joint project, the staff and industry developed representative FLEX scenarios for the testing of the IDHEAS-ECA method.
The purposes of the HRA method efforts are to improve HRA methods and consistency among HRA practitioners. This will help improve HRA/PRA quality and provide a stronger basis for risk-informed regulatory actions.
FY 2020
FY 2020
The following tasks were accomplished in FY 2020:
- Updated the Draft IDHEAS General Methodology (IDHEAS-G):
- Revised the report to address ACRS and public members' comments
- Updated the new function of IDHEAS-G for generalizing and integrating human error data of various sources to calculate human error probabilities (HEPs)
- Developed the conceptual IDHEAS dependency model
- Presented IDHEAS-G to ACRS PRA Subcommittee on 9/23/2020
- Completed the development of IDHEAS Events and Conditions Assessment Method (IDHEAS-ECA).
- IDHEAS-ECA is a human reliability analysis (HRA) method that is based on the General Methodology of an Integrated Human Event Analysis System (IDHEAS-G). The method is intended to be used in event and condition assessment (ECA) of nuclear power plants.
- IDHEAS-ECA supports probabilistic risk assessment (PRA) applications by analyzing human events and estimating human error probabilities. The application scope of IDHEAS-ECA is broad because the performance-influencing factor (PIF) structure, which models the context of a human failure event (HFE), is comprehensive. The method covers all the PIFs in existing HRA methods and the factors reported in broad literature and in nuclear-specific human events. Because of the comprehensiveness of the PIF structure, IDHEAS-ECA can model the context of HFEs inside and outside an NPP control room—including the use of flexible and coping strategies (FLEX) equipment—and during different plant operating states (i.e., at-power and shutdown). IDHEAS-ECA can be used in PRA applications; for example, the significance determination process (SDP), accident sequence precursor (ASP) program, and risk-informed licensing reviews.
- To facilitate the use of IDHEAS-ECA, the NRC staff developed the IDHEAS-ECA Software Tool to calculate the HEPs of HFEs analyzed in the IDHEAS-ECA process.
- The IDHEAS-ECA Software has been evaluated by NRR users, tested by the development team, and approved by the NRC's OCIO for installation on NRC computers.
- IDHEAS-ECA method and guidance report was published as an NRC Research Information Letter RIL-2020-02.
- IDHEAS-ECA Software Version 1.0 and 1.1 was released to the public.
- Completed HRA evaluation of representative human actions in FLEX Strategies using the IDHEAS-ECA Software:
- NRC staff and industry jointly developed two scenarios using FLEX equipment for evaluation, a FLEX-designed scenario in a severe seismic event and the other a non-FLEX-designed scenario of using FLEX equipment in an outage.
- A group of NRC and industry HRA analysts estimated the HEPs of the selected human actions in the two FLEX-use scenarios using IDHEAS-ECA Software.
- The NRC staff documented the scenarios and evaluation results in a draft (publicly available) report and presented the results to ACRS PRA Subcommittee on 09/23/2020.
The following activities are on-going:
- The NRC staff are collecting feedback and suggestions from the NRC and industry PRA/HRA practitioners on improving IDHEAS-ECA.
- The NRC staff are planning on testing the IDHEAS dependency model and developing guidance for NRC HRA applications.
The purposes of the HRA method efforts are to improve HRA methods and consistency among HRA practitioners. This will help improve HRA/PRA quality and provide a stronger basis for risk-informed regulatory actions.
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National Fire Protection Association (NFPA) Standard 805
Summary Description
NFPA 805 enables licensees to use PRA inputs generated using their PRA models to comply with fire protection regulations on a risk-informed manner. In 2004, the Commission approved a voluntary risk-informed and performance-based fire protection rule for existing nuclear power plants. The rule endorsed NFPA consensus standard NFPA 805, "Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants." A safety evaluation in December 2010 approved the Oconee NFPA 805 pilot application. In addition, the NEI developed NEI 04-02, "Guidance for Implementing a Risk-Informed, Performance-Based Fire Protection Program Under 10 CFR 50.48(c)," dated September 2005. The staff endorsed NEI 04-02 in RG 1.205, "Risk-Informed, Performance-Based Fire Protection for Existing Light-Water Nuclear Power Plants," issued in May 2006. To date, nearly half of the nuclear power units operating in the United States, including those that participated in the pilot program, have committed to transition to NFPA 805 as their licensing basis. The Oconee Nuclear Station (Oconee) and Shearon Harrison Nuclear Power Plant (Shearon Harris) were the pilot plants for 10 CFR 50.48(c). In June 2010, a safety evaluation approved the Shearon Harris NFPA 805 pilot application. A safety evaluation in December 2010 approved the Oconee NFPA 805 pilot application. NEI 04-02 was revised (Revision 2) in April 2008 and the staff revised RG 1.205 (Revision 1) in December 2009 to reflect lessons learned from the pilot reviews. The staff developed NUREG-800, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition," Chapter 9, "Auxiliary Systems," Section 9.5.1.2, "Risk-Informed, Performance-Based Fire Protection Program Review Responsibilities," issued December 2009, to provide staff guidance for the review of licensee applications to transition to NFPA 805. In addition, the NRC developed a Frequently Asked Question process to review and establish a preliminary staff position on NFPA 805 application, review, and implementation issues.
Lessons learned from the pilot applications indicated that the staff and the industry underestimated the complexity and resources necessary to complete the reviews. In SRM-SECY-11-0033, "Proposed NRC Staff Approach to Address Resource Challenges Associated with Review of a Large Number of NFPA 805 License Amendment Requests," dated April 20, 2011, the Commission approved the staff's recommendation to increase resources to review NFPA 805 applications, develop a staggered review process, and modify the current enforcement policy. The NRC sent the revised enforcement policy to the Commission in SECY-11-0061, "A Request to Revise the Interim Enforcement Policy for Fire Protection Issues on 10 CFR 50.48(c) to Allow Licensees to Submit License Amendment Requests in a Staggered Approach," dated April 29, 2011 and approved in SRM SECY-11-0061, dated June 10, 2011. To enhance the efficiency and effectiveness of the NFPA 805 application reviews, the industry developed an application template and the staff developed a safety evaluation template. The staff has received 29 applications to date and does not expect any additional applications to be submitted.
Previous Fiscal Years
FY 2015
The NRC staff issued six non-pilot NFPA 805 license amendments with three more expected to be completed by the end of the year. Thirteen LARs are currently under review. Additional FY 2015 information is available.
FY 2016
The NRC staff issued seven non-pilot NFPA 805 license amendments. Five license amendment requests (LARs) are currently under review. Additional FY 2016 information is available.
FY 2017
The NRC staff issued five non-pilot NFPA 805 license amendments. Two LARs are currently under review. Additional FY 2017 information is available.
The NRC staff issued one non-pilot license amendment and received one additional license amendment request. Two requests are currently under review.
Risk-Informed Licensing Reviews. NFPA 805 is a performance-based standard, endorsed via 10 CFR 50.48(c) that critically depends on risk information in the form of Fire PRA to enable licensees to transition from existing "deterministic" fire protection programs to ones that are "risk-informed, performance-based." Fire PRA is an integral part of the new licensing basis, and includes both quantitative evaluations of base risk and changes to base risk in accordance with RG 1.174 guidelines as well as supporting qualitative considerations, such as traditional defense in depth and safety margin, also as per RG 1.174.
FY 2019
As mentioned previously, NFPA 805 enables licensees to use PRA inputs generated using their PRA models to comply with fire protection regulations on a risk-informed manner. The NRC staff issued one license amendment and did not receive any additional license amendment requests. One request is currently under review.
Risk-Informed Licensing Reviews. NFPA 805 is a performance-based standard, endorsed via 10 CFR 50.48(c) that critically depends on risk information in the form of Fire PRA to enable licensees to transition from existing "deterministic" fire protection programs to ones that are "risk-informed, performance-based." Fire PRA is an integral part of the new licensing basis, and includes both quantitative evaluations of base risk and changes to base risk in accordance with RG 1.174 guidelines as well as supporting qualitative considerations, such as traditional defense in depth and safety margin, also as per RG 1.174.
FY 2020
FY 2020
Forty-six operating nuclear power reactors committed to transition to NFPA 805 and as of the end of the third quarter of fiscal year (FY) 2020, all 46 reactor units have received license amendments. All reactor units except for 8 have fully completed the transition. Transition completion is controlled by license condition and transition is considered completed when all implementation items and modifications required by NFPA 805 have been completed. Although there are no additional licensees scheduled to submit license amendment requests to transition to NFPA 805, the NRC staff has received 20 requests from NFPA 805 licensees requesting additional changes. Of these 20 requests, all have been completed except for one that is currently under review and scheduled to be completed in the first quarter of FY 2021.
As a result of NFPA 805, two NRC guidance documents are in the process of being revised, which include: Regulatory Guide 1.205, Risk-Informed, Performance-Based Fire Protection for Existing Light-Water Nuclear Power Plants, and Regulatory Guide 1.191, Fire Protection Program for Nuclear Power Plants During Decommissioning And Permanent Shutdown. The draft revisions for public comment of these regulatory guides should be available by the first quarter of FY 2021, and issuance of the final revisions should occur by the second quarter of FY 2021.
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Assess Debris Accumulation on Pressurized Water Reactor (PWR) Sump Performance, Generic Safety Issue (GSI)-191
Summary Description
This generic issue concerns the possibility that following a Loss of Coolant Accident (LOCA) in a PWR, debris accumulation on the containment sump strainer(s) may inhibit flow to the Emergency Core Cooling System (ECCS) and the Containment Spray System. An additional concern is that debris may penetrate or bypass the sump strainer(s) and block flow to the core.
As described below, the staff has identified several options including risk-informed options to address this generic safety issue. When using the risk-informed option to disposition GSI-191, the licensees use inputs from their PRA models which may including bounding analyses. Also, when using risk-informed options, licensees must address all five principles of risk-informed decision making in Regulatory Guide (RG) 1.174.
In SECY-12-0093, dated July 9, 2012, the staff identified several options for resolving GSI-191. These options included two risk-informed approaches. One approach, piloted by South Texas Project (STP), would address both strainer and in-vessel effects using risk. The other approach would use risk for in-vessel effects and would resolve strainer issues deterministically.
The Commission endorsed the staff's proposed options for resolving GSI-191 in SRM-SECY-12-0093, dated December 14, 2012. Since the Commission's endorsement, 11 licensees (18 units) have proposed to implement a risk-informed approach to address GSI-191 concerns. In consideration of the additional time required to implement risk informed approaches and/or complete further testing, subject licensees have implemented mitigative measures to address the potential for debris blockage of the strainer or reactor core.
SRM-SECY-12-0093, Title 10 of the Code of Federal Regulations (CFR) Section 50.46c, addresses ECCS performance during a LOCA. SECY-12-0034, dated January 7, 2013, directed that a provision allowing NRC licensees, on a case-by-case basis, to use risk informed alternatives should be included as part of proposed revisions to 10 CFR 50.46c. The proposed rule containing this provision was published in the Federal Register on March 24, 2014 (79 FR 16106).
In accordance with SRM-COMSECY-13-006, dated May 9, 2013, draft guidance related to implementation of the GSI-191 risk informed alternative was developed in parallel with its review of the STP pilot submittal, and published it in the Federal Register for public comment on April 20, 2015 (75 FR 21658).
Previous Fiscal Years
FY 2015
The staff has continued to review the STP pilot and has published draft guidance (DG-1322) for licensees choosing to implement the optional, risk-informed provision in 10 CFR 50.46c.The draft guide (which will ultimately be published as RG 1.229) was issued for public comment on April 20, 2015. The public comment period closed on July 6, 2015, and the staff has since resolved all public comments and updated the DG accordingly. RG 1.229 is scheduled to be issued with the new 10 CFR 50.46c rule in the second quarter of FY 2016.
FY 2016
Preparations were made to ensure that final regulatory guidance (RG 1.229, "Risk-Informed Approach for Addressing the Effects of Debris on Post-Accident") could be issued concurrent with the revised 10 CFR 50.46c rule. Proposed 50.46c rule changes were still pending Commission approval at the end of FY16. Several pre-submittal public meetings were conducted in preparation for forthcoming GSI-191 risk-informed closure submittals.
FY 2017
The staff completed its review of the STP pilot and issued a safety evaluation and license amendment approving the risk informed closure of GSI-191 for STP. Currently, eight additional units are expected to request similar risk-informed closures.
FY 2018
The staff is currently expecting license amendment requests for eight additional units.
Site-specific closeout of GSI-191 according to the risk-informed approach involves the use of a systematic processes to evaluate the risk from debris in terms of core damage frequency (CDF) and large early release frequency (LERF). The systematic risk assessment would rely on, at minimum, a plant-specific at-power, internal events probabilistic risk assessment (PRA) and take into consideration all hazards, initiating events, and plant operating modes. The risk attributable to debris would be compared to the risk calculated assuming debris is not present yielding values for the change in CDF and LERF (∆CDF and ∆LERF, respectively).
Licensees pursuing risk-informed approaches to address GSI-191 concerns, will be submitting license amendment requests subject to RG 1.174, Revision 2, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decision on Plant-Specific Changes to the Licensing Basis."
FY 2019
GL 2004-02 has requested licensees to perform an evaluation of the emergency core cooling system (ECCS) and containment spray system (CSS) recirculation functions considering potential post-LOCA debris impacts and, if appropriate, take additional actions to ensure system function.
On November 30, 2018, the Director of the Office of Nuclear Reactor Regulation (NRR) signed a letter to the PWR Owners Group Chairman (ADAMS Accession Number ML18311A297) stating that the NRC staff was reevaluating the closure path for GSI-191 and Generic Letter (GL) 2004-02, particularly related to in-vessel downstream debris effects. On June 13, 2019, the NRC staff issued a technical evaluation report of in-vessel downstream debris effects (ADAMS Accession Number ML19178A252), and subsequently, on July 23, 2019, the NRC closed out GSI-191 (ADAMS Package Accession Number ML19203A303) primarily because the NRC staff concluded that complex technical and safety impacts of downstream and chemical effects are well understood and that all safety significant issues have been adequately addressed by most licensees.
Although NRC closed out GSI-191, the staff continues to review licensee responses to GL 2004-02.
Licensees pursuing risk-informed approaches to respond to GL 2004-02 can also submit license amendment requests following the guidance in RG 1.174, Revision 3, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decision on Plant-Specific Changes to the Licensing Basis" (ADAMS Accession Number ML17317A256).
FY 2020
FY 2020
The staff continues working with individual licensees on closure of GL 2004-02. Closure requires plants to address both strainer and in-vessel issues. This year the staff continued work to facilitate closure of the in-vessel portion. The staff developed guidance (ADAMS Accession No. ML19228A011v) for NRC staff review of in-vessel submittals. This in-vessel guidance risk-informs plant-specific resolution by describing several defined paths licensees may follow to resolve GL 2004-02. These are based on plant specific configurations, including the relative risk and available safety margin for that configuration. This, in turn affects the type and depth of supporting information needed for each. The staff also worked with the PWROG to develop related guidance for licensee submittals for in-vessel closure. About one-third of the plants closed both aspects of the issue using deterministic methods. Most of the plants completed their strainer evaluations using deterministic methods. Some of the plants that have not finalized their strainer evaluations plan to use a transition break size methodology that accounts for the risk associated with breaks of different sizes. A few plants plan to use fully risk-informed evaluations to close the strainer portion of GL 2004-02 using methods like the STP pilot discussed above. All of the remaining plants will use the risk-informed in-vessel guidance to close out the in-vessel portion of GL 2004-02. The staff will review submittals as they are submitted by each licensee.
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Develop Risk-Informed Improvements to Standard Technical Specifications (STS)
Summary Description
The staff continues to work on the risk-informed technical specifications (RITS) initiatives to add a risk-informed component to the STS. The following summaries highlight these activities:
Initiative 1, "Modified End States," would allow licensees to repair equipment during hot shutdown rather than cold shutdown. The Topical Reports (TRs) supporting this initiative for boiling water reactor (BWR), Combustion Engineering (CE), Babcock & Wilcox (B&W), and Westinghouse Electric Company (Westinghouse) plants have been approved, and revisions to the BWR, CE, B&W, and Westinghouse STS are available at ADAMS Accession Nos. ML093570241 and ML103360003.
Initiative 4b, "Risk-Informed Completion Times," allows licensees to use risk insights to extend the "completion times" by which an inoperable SSC controlled by technical specifications must be restored. The risk-informed completion time could be shorter than that required by technical specifications given actual plant conditions, or could be much longer, up to a "backstop" of 30 days. From a safety perspective, the program uses a real-time view of plant conditions to determine an appropriate time for key equipment to be out of service and focuses plant attention on issues of the highest safety significance. Licensees also benefit from the ability to schedule maintenance activities over a longer time period if appropriate. The plant-specific Probabilistic Risk Analysis (PRA) model is utilized to generate the risk metrics following a change in the plants configuration resulting in a quantifiable change in risk allowing for a flexible completion time for the Conditions in the Technical Specifications of the nuclear plant.
As reported previously in SECY-07-0191, "Implementation and Update of the Risk-Informed and Performance-Based Plan," dated October 31, 2007, the staff issued the license amendment for the first pilot plant, South Texas Project (STP), in July 2007. In July 2010, Southern Nuclear Company (SNC) submitted a letter of intent for Vogtle Electric Generating Plant (VEGP) (Units 1 and 2) to implement RITS Initiative 4b. The NRC granted an associated fee waiver request and received a pilot application in September 2012. The NRC staff completed the review of the application in 2017. The associated Technical Specification Task Force guidance (TSTF-505) to revise the STS was published in March 2012. Five additional applications to implement TSTF-505 have been received and are currently being reviewed by the technical staff. The five additional applications were received on November 25, 2013; December 5, 2014; December 23, 2014; July 31, 2015 and February 25, 2016. The five additional applications were not classified as "pilot applications."
Initiative 6, "Add Actions to Preclude Entry into LCO 3.0.3," modifies technical specification action statements for conditions that result in a loss of safety function related to a system or component included within the scope of the plant technical specifications. The staff approved the industry's TR for CE nuclear power plants (Revision 2 to WCAP-16125-NP-A, "Justification for Risk-Informed Modifications to Selected Technical Specifications for Conditions Leading to Exigent Plant Shutdown") in August 2010. The associated Technical Specification Task Force (TSTF) guidance (Revision 5 of TSTF-426) to revise the CE STS was submitted for NRC review by letter dated November 2011. Based on the approved CE TR, the industry has also submitted requests to revise the B&W STS (Revision 0 of TSTF-538) and the STS for BWRs (Revision 0 of TSTF-540) in March 2012 and May 2012, respectively. However, these TSTFs were withdrawn per letters dated January 6, 2014, and October 6, 2014, after the NRC requested additional information and the participating licensees decided not to pursue these initiatives.
Previous Fiscal Years
FY 2015
The NRC staff continued review of STS initiatives as they were received. Additional FY 2015 information is available.
FY 2016
The NRC staff performed reviews of STS initiatives-based license amendment applications as they were received. Additional FY 2016 information is available.
FY 2017
NRC suspended adoption of TSTF-505, detailing challenges with continuing to review amendments against it. Six LARs to implement a plant-specific 4b amendment were under review in FY 2017. Additionally, NRC met with industry representatives in several public meetings to discuss resolution of TSTF-505 issues, such as conditions which were accepted for use in program, and guidance for addressing other aspects of the application. The NRC staff, however, completed and issued the safety evaluation approving Vogtle Electric Power Generating Plants (Units 1& 2) to adopt Tech Spec 4b.
FY 2018
NRC issued the model safety evaluation for TSTF-505 alongside Revision 2 of TSTF-505. NRC received seven additional License Amendment Requests for Review. To enhance the efficiency of review, NRC staff conducted a number of on-site audits and disseminated lessons-learned at various public and industry led meetings. Based on information received from industry survey, a large majority of plants are planning to submit LARs and request staff approval to implement TSTF-505. NRC completed and issues several license amendments (Turkey Point, Calvert Cliffs).
FY 2019
The NRC has issued amendments for TSTF-505 (St. Lucie, Palo Verde, Farley), bringing the total of issued TSTF-505 and Initiative 4b amendments to 13.
FY 2020
FY 2020
The NRC continued receiving and reviewing License Amendment Applications for TSTF-505 Revision 2. The NRC issued six additional amendments, bringing the total of issued amendments to nineteen.
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Implement 10 CFR 50.69: Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors
Summary Description
In 1998, the Commission decided to consider issuing new regulations that would provide an alternative risk-informed approach for special treatment requirements in the current regulations for power reactors. The NRC published the final rule (10 CFR 50.69, "Risk-Informed Categorization and Treatment of Structures, Systems and Components [SSCs] for Nuclear Power Reactors") in the Federal Register on November 22, 2004 (69 FR 68008). The NRC staff issued Regulatory Guide (RG) 1.201, Revision 1, "Guidelines for Categorizing Structures, Systems, and Components in Nuclear Power Plants According to Their Safety Significance," in May 2006. The provisions of 10 CFR 50.69 allow for the adjustment of the scope of SSCs subject to special treatment requirements based on an integrated and systematic risk-informed process. Special treatment refers to those requirements that provide increased assurance beyond normal industry practices that SSCs perform their design basis functions (e.g., quality assurance, testing, inspection, condition monitoring, assessment, and evaluation). For SSCs categorized as low safety significance (LSS), alternative treatment requirements may be implemented in accordance with the regulation. For SSCs determined to be of high safety significance (HSS), requirements may not be changed. 10 CFR 50.69 and its implementation relies on risk insight and metrics, such as importance measures, to categorize the safety significance of systems, structures, and components (SSCs). The plant-specific Probabilistic Risk Analysis (PRA) model is utilized to generate the risk metrics used for the categorization resulting in a quantifiable method of determining the risk significance of the components on the safe operation of the nuclear plant.
By letter dated December 6, 2010, the Southern Nuclear Company (SNC) informed the NRC of its intent to submit a license amendment request for implementation of 10 CFR 50.69 for Vogtle Electric Generating Plant (VEGP) Units 1 and 2, and requested pilot plant status and a waiver of review fees. By letter dated June 17, 2011, the staff informed SNC that the NRC granted the fee waiver request for the proposed licensing action in accordance with 10 CFR 170.11(b). SNC submitted a pilot plant application to implement 10 CFR 50.69 on August 31, 2012. By letter dated December 17, 2014, the NRC staff issued a License amendment to SNC revising the licensing basis for the VEGP by adding license conditions that allow for the voluntary implementation of 10 CFR 50.69. Lessons learned from the application review will be used to revise the associated industry guidance and RG 1.201.
In addition, the NRC staff issued draft Inspection Procedure 37060, "10 CFR 50.69 Risk Informed Categorization and Treatment of Structures, Systems, and Components Inspection," on February 16, 2011. The Nuclear Energy Institute (NEI) and one licensee provided comments on the procedure. The NRC staff addressed the comments and issued the revised inspection procedure in 2011. The NRC will focus its inspection efforts on the most risk-significant aspects related to implementation of 10 CFR 50.69 (i.e., proper categorization of SSCs and treatment of Risk-Informed Safety Class [RISC]-1 and RISC-2 SSCs).
Previous Fiscal Years
FY 2015
Completed the pilot application for the Vogtle Electric Generating Plant (VEGP) in December 2014. Additional FY 2015 information is available.
FY 2016
No new submittals seeking to implement 10 CFR 50.69 were received by the NRC in FY 2016. The NRC staff met with industry representatives in August 2016 to discuss future 50.69 LAR submittals and their content (ADAMS Accession Number ML16250A548).
FY 2017
NRC has received seven submittals to implement 10 CFR 50.69 in FY 2017. Additionally NRC met with industry representatives in several public meetings to discuss 50.69 topics of interest, such as content of License Amendment Requests, and industry proposed deviations from RG 1.201 guidance for addressing seismic and fire risk (ADAMS Accession Numbers ML17027A251, ML17177A063, ML17265A020).
FY 2018
NRC issued the safety evaluation for Limerick Nuclear Generating Station. NRC received seven additional License Amendment Requests for Review. In FY 2018 the NRC licensing staff was in the process of reviewing 13 license amendment requests applicable to 24 additional operating units. To enhance the efficiency of review, NRC staff conducted a number of on-site audits and disseminated lessons-learned at various public and industry led meetings. Based on information received from industry survey, a large majority of plants are planning to submit LARs and request staff approval to implement 10 CFR 50.69. The NRC staff continued its meetings with licensees to discuss industry's proposed approach to implementing 10 CFR 50.69 for licensees that do not have seismic probabilistic assessments of seismic margins analysis (ADAMS Accession Numbers ML17305A242, ML18025B737, ML18143B668, and ML18250A193).
FY 2019
The NRC has issued nine amendment for 50.69 (ADAMS Accession Numbers ML18243A280, ML18264A092, ML18263A232, ML18289A378, ML19149A471, ML19192A012, ML19179A135, ML19176A421, and ML19205A289), bringing the total of issued 50.69 amendments to eleven. An additional five are under technical review.
The NRC staff made significant progress in reviewing new alternative approaches for addressing fire and seismic risk in the categorization process. For plants that did not develop a fire PRA the industry proposed to use the fire safe shutdown equipment list developed to demonstrate compliance with 10 CFR Part 50, Appendix R. One plant has received the amendment to use this alternative fire approach. With regards to the seismic risk, the industry proposed a three-tiered approach to implementing 10 CFR 50.69 for plants with low, medium and high seismic hazard/margin (EPRI Report 3002012988) for those licensees that do not have seismic probabilistic risk assessments of seismic margins analysis. One lead plant submitted for the Tier 1 of the approach and is under technical review. Another lead plant expected to submit for the Tier 2.
FY 2020
FY 2020
The NRC continued receiving and reviewing 50.69 License Amendment Applications. The NRC issued additional amendments for 50.69, bringing the total of issued amendments to seventeen. The NRC completed the review for one plant that applied the alternative seismic methodology proposed in EPRI Report 3002012988, for Tier 1 (low) seismic risk (ADAMS Accession Number ML19330D909). The NRC is in process of reviewing an application for a plant in Tier 2 (medium) seismic risk.
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Graded Approach to the Use of Safety Significance in the Low Safety Significance Issue Resolution Process
Summary Description
NRC is exploring how it can enhance existing processes and procedures to better focus licensee and NRC regulatory attention on design and operational issues commensurate with their importance to public health and safety and common defense and security. This effort is sometimes referred to as the Low Safety Significance Issue Resolution process. It will utilize quantitative or qualitative risk insights. These risk insights may be gleaned from an assessment using the risk triplet (What can go wrong? How likely is it? What are the consequences?) or when appropriate, PRA models. Issues potentially impacting safety are promptly identified, fully evaluated, and promptly addressed, commensurate with their safety significance. However, the NRC does not always have clear guidance on evaluating significance prior to the expenditure of significant resources in evaluating an issue. For example, as a result of NRC an inspection, issues and conditions are identified that appear to be potential violations of governing requirements. Sometimes, there is a lack of clarity in the plant licensing basis that results in a difference in view between the licensee and the NRC as to whether the licensee is in compliance with its licensing basis. While these situations represent the exception, in practice, resolving these issues through the NRC's current processes has been resource intensive, inefficient, and untimely in many cases. The COM-106 program is the procedure by which the Office of Nuclear Reactor Regulation provides information assistance to other NRC offices and is currently being enhanced. The COM-106 program routinely fields unresolved questions from the NRC Regional Offices and has experienced such examples in the past. For some licensing basis issues, past case studies demonstrate an imbalanced expenditure of time, resources, and effort compared to the underlying issue's significance to public health and safety, and common defense and security.
Previous Fiscal Years
FY 2019
Work to date has focused on revisions to inspection guidance, the COM-106 process, and licensing processes, as they pertain to the type of issues described above. Working groups were formed, external stakeholder feedback has been solicited via three public meetings, some process enhancements are being implemented, and some recommendations for additional changes are being made. As an example, the aforementioned COM-106 process is being revitalized to feature a streamlined 3- step graded approach commensurate with issue significance, with timelier responses. Further the enhancement is expected to include an integrated team approach to address issue screening, scoping, evaluation and early alignment in the issue lifecycle. This screening and evaluation include consideration of an issue's safety significance, inclusions of additional licensing basis expertise, consideration of a resolution if easily achievable, and consideration of whether there is another agency process that is more suitable to resolving the issue, all prior to entering in to an in-depth evaluation. These changes to COM-106, in concert with accompanying changes to inspection guidance, will promote resource expenditures commensurate with an issue's significance. Separately, additional work is being undertaken to scope process improvements that would have an analogous benefit for compliance issues.
FY 2020
FY 2020
Staff completed the update to NRR Office instruction COM-106, "Technical Assistance Request" in August 2020 (ADAMS Accession No. ML19176A098). The recommendations of the LSSIR working group were provided to the NRR Office director in a memorandum (ADAMS Accession No. ML19260G224), and subsequently endorsed in their entirety (ADAMS Accession No. ML20022A032). A major recommendation from the working group resulted in the revision of Inspection Manual Chapter (IMC) 0612, Appendix B, "Issue Screening," and IMC 0611, "Power Reactor Inspection Reports" to enable inspection efforts associated with very LSS issues, for which there is a lack of clarity regarding its licensing basis standing, to be discontinued early in the inspection process. The revision to IMC 0612B was issued on 12/12/2019 and the revision to IMC 0611 was issued on 1/7/2020.
In FY 2020, staff began an initiative to entitled Risk Informed Process for Evaluations (RIPE) to address low safety significant compliance issues using existing regulations under 10 Code of Federal Regulations (CFR) 50.12, "Exemptions, and 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit." RIPE is considered as an extension to LSSIR. Its objective is to focus NRC and licensee resources on the most safety significant issues by addressing low safety compliance issues in an efficient and predictable manner consistent with our Principles of Good Regulation. The process plans to leverage existing regulations and risk initiatives to allow licensees to justify plant-specific exemptions or license amendment requests using a streamlined NRC review process. In addition, RIPE incentivizes further development and use of probabilistic risk assessment and risk-informed applications.
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Guidance for Unattended Opening Evaluations
Summary Description
See FY 2019.
Previous Fiscal Years
FY 2019
NSIR staff began interactions with external stakeholders on revising current guidance regarding the evaluation of unattended openings (i.e., those that intersect a security boundary at a facility, such as underground pathways) to incorporate risk information, notably the dimensions for openings that must be protected. The updated guidance will consider three-dimensional information, rather than the current guidance that is based on a two-dimensional opening. The staff is reviewing the revision to the industry guidance document (NEI 09-05) for acceptance.
FY 2020
FY 2020
NEI 09-05, (Guidance on the Protection of Unattended Openings that Intersect a Security Boundary, Supplement) revision is being evaluated by staff.
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Risk-Informed Adversary Timeline Calculations
Summary Description
See FY 2019.
Previous Fiscal Years
FY 2019
NSIR staff began the development of a more risk-informed process to increase attack timeline realism by incorporating delays based on active and passive features of a physical protection program. This is anticipated to be accomplished through review and approval of an industry proposal, which is expected to be received in Q3 of FY 2020.
FY 2020
FY 2020
NSIR staff began the development of a more risk-informed process to increase attack timeline realism by incorporating delays based on active and passive features of a physical protection program. This is anticipated to be accomplished through review and approval of an industry proposal, which is expected to be received in Q1/Q2 of FY 2021.
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Transition from Physical Security Plan to Safeguards Contingency Plan
Summary Description
See FY 2019.
Previous Fiscal Years
FY 2019
NSIR staff began to evaluate the process licensees use as they transition from their physical security plan (PSP) to their safeguards contingency plan (SCP) during a safeguards contingency event at a site. The staff used risk insights in determining that specific requirements in the PSP, including active compensatory measures, may be altered during a safeguards contingency event if the implementation of the remaining unaltered portions of the PSP, working in conjunction with implementation of the SCP, ensures that the general performance objectives of 10 CFR 73.55 are met and continue to provide reasonable assurance of adequate protection at all times. This determination will allow licensees to revise their procedures that provide guidance on evaluating changes to compensatory measures and their potential to impact the overall effectiveness of the physical protection program. In addition, the staff developed associated Security Frequently Asked Questions (SFAQ) and will engage with NEI and other industry stakeholders to solicit input, consistent with the staff-accepted SFAQ process.
FY 2020
FY 2020
The staff engaged with NEI and other industry stakeholders to develop associated Security Frequently Asked Questions.
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Emergency Preparedness (EP) Program Review 24-Month Frequency Performance Indicators Development to Satisfy 10 CFR 50.54(t) Requirements
Summary Description
See FY 2019.
Previous Fiscal Years
FY 2019
The NRC staff is reviewing a White Paper submitted by the Nuclear Energy Institute (NEI), "Implementing a 24-Month Frequency for Emergency Preparedness Program Reviews," September 2019. Prior to 2018, 10 CFR 50.54(t), which requires licensees to review all program elements of their emergency preparedness programs no less frequently than every 12 months. However, this regulation was changed to allow for a 24-month frequency with the monitoring of EP Performance Indicators (PI). This change was made prior to the development of the Reactor Oversight Process (ROP) and the subsequent EP Cornerstone PIs. The NEI white paper proposes to adopt the ROP PIs in support of the 50.54(t) 24-month review frequency. The staff is using a risk-informed approach to analyze the merits of this proposal. (Note that the current ROP EP Cornerstone PIs may need to be revised as a result of this risk-informed activity). The staff expects to complete its analysis in FY 2020.
FY 2020
FY 2020
The NRC staff reviewed the White Paper submitted by the Nuclear Energy Institute (NEI), "Implementing a 24-Month Frequency for Emergency Preparedness Program Reviews," September 2019 and conducted public meetings during FY 2020 Qs 1/2. NRC is planning on endorsing the White Paper in the upcoming revision to RG 1.101, which is expected to be in draft for issuance during FY2021. The staff used a risk-informed approach to analyze the merits of this proposal. (Note that the current ROP EP Cornerstone Performance Indicators may need to be revised as a result of this risk-informed activity).
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Page Last Reviewed/Updated Tuesday, December 29, 2020