Cross-Cutting 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 that substantially crosscut multiple subarenas:
- Update RG 1.200, An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities
- PRA Standards Development
- Industry Peer Review Guidance Development
- Risk-Informed Steering Committee (RISC)
- NRC "Grow Your Own" PRA Capability
- Update Regulatory Guide 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant Specific Changes to the Licensing Basis
- Update NUREG 1855, Guidance on the Treatment of Uncertainties Associated with PRAs in Risk-Informed Decisionmaking
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Update RG 1.200, An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities
Summary Description
Regulatory Guide (RG) 1.200 provides the staff position regarding what constitutes an acceptable PRA and how the PRA standards and peer review guidance are used to demonstrate conformance with the staff position. In this regard, RG 1.200 provides a definition for what constitutes a PRA and a staff position on PRA acceptability addressing the (1) scope of a PRA, (2) technical elements of a PRA, (3) level of detail of a PRA, and (4) plant representation in the PRA model. RG 1.200 also provides a staff position on consensus PRA standards and industry peer review PRA programs, demonstration of the acceptability of a PRA, and documentation to support a regulatory submittal. RG 1.200 also provides the NRC endorsement of the published ASME/ANS PRA standards and the NEI peer review guidance documents.
Associated Risk-Informed Activities below:
FY 2015
Staff and industry continue to use RG 1.200 in support of risk-informed activities.
FY 2016
Staff and industry continue to use RG 1.200 in support of risk-informed activities. Staff developed a draft position for a process for closure of peer review findings. This staff position has not yet been incorporated into RG 1.200.
FY 2017
Staff and industry continue to use RG 1.200 in support of risk-informed activities. Staff initiated efforts for Revision 3 of RG 1.200.
Risk-Informed Basis
Under this activity the infrastructure is developed to support risk-informed decision-making. The purpose of this activity is to provide the agency position on an acceptable base PRA such that the results from the PRA can be used in risk-informed decision-making.
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PRA Standards Development
Summary Description
Staff participates with the ASME and ANS efforts to develop PRA Standards. ASME and ANS work together under the Joint Committee for Nuclear Risk Management (JCNRM). JCNRM is developing a suite of standards which (1) address operating LWRs, advanced LWRs in the design certification stage, and non-LWRs, (2) address all operating modes (at-power and low power and shutdown), (3) address both internal hazards (i.e., internal events, internal floods and internal fires) and external hazards (seismic, high winds, external floods and others), and (4) address all risk metrics (CDF, LERF/LRF, radiological release frequency, and consequences. These standards include:
- Level 1 (CDF)/LERF PRA standard for at-power conditions, both internal (i.e., internal events, floods and fires) and external (i.e., fires, seismic, high winds, floods and others) hazards for operating LWRs. This standard was published as an ANSI standard in 2008, Addendum A in 2009 and Addendum B in 2013.
- Level 2 (radiological release frequency) PRA standard for all operating modes and for both internal and external hazards for LWRs. This standard was published as an ASME/ANS Trial Use standard in 2015.
- Level 3 (consequences) PRA standard for nuclear facilities and for all operating modes and both internal and external hazards. This standard has not been published.
- LPSD PRA standard for Level 1/LERF for LWRs. This standard was published as an ASME/ANS Trial Use standard in 2015.
- Advanced LWR PRA standard for new LWRs in the design certification phase addressing Level 1/LERF. This standard has not been published.
- Non-LWR PRA standard for all three PRA Levels and all operating modes for both internal and external hazards and addressing multi-units at a single site. This standard was published as an ASME/ANS Trial Use standard in 2009.
To date, the staff has endorsed the Level 1/LERF PRA standard, specifically the 2009 addendum (i.e., ASME/ANS RA-Sb-2009).
FY 2015
Staff continues to support JCNRM efforts on the various standard activities:
- working on the new edition to the published Level 1 (CDF)/LERF PRA standard
- published trial use Level 2 PRA standard
- developing the Level 3 PRA standard for trial use
- piloting the published trial use LPSD PRA standard
- developing the Advanced LWR PRA standard for trial use
- piloting the published trial use non-LWR PRA standard
FY 2016
Staff continues to support JCNRM efforts on the various standard activities:
- working on the new edition to the published Level 1 (CDF)/LERF PRA standard
- piloting the published trial use Level 2 PRA standard
- developing the Level 3 PRA standard for trial use
- piloting the published trial use LPSD PRA standard
- developing the Advanced LWR PRA standard for trial use
- piloting the published trial use non-LWR PRA standard
FY 2017
Staff continues to support JCNRM efforts on the various standard activities:
- working on the new edition to the published Level 1 (CDF)/LERF PRA standard
- JCNRM published a Code Case which provides an alternate approach to Part 5 of the standard addressing seismic PRA
- NRC developed draft comments on the Code Case (for approval) and planned to request external stakeholder feedback
- piloting the published trial use Level 2 PRA standard
- developing the Level 3 PRA standard for trial use
- piloting the published trial use LPSD PRA standard
- developing the Advanced LWR PRA standard for trial use
- piloting the published trial use non-LWR PRA standard
Risk-Informed Basis
Under this activity the infrastructure is developed to support risk-informed decision-making. The purpose of this activity is to provide the agency position on an acceptable base PRA such that the results from the PRA can be used in risk-informed decision-making.
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Industry Peer Review Guidance Development
Summary Description
Staff reviews and endorses the PRA peer review guidance issued by NEI in RG 1.200 for how to demonstrate conformance with the ASME/ANS PRA standards. RG 1.200 provides the staff position for what constitutes an acceptable peer review program. The NEI guidance documents include:
- NEI 00-02 (published in 2000) provides the initial peer review guidance for internal events and internal floods Level 1 PRA. It also include a self-assessment to address the gap between the review criteria in NEI 00-02 and the ASME/ANS PRA standard. It is endorsed in RG 1.200.
- NEI 05-04 (published in 2005) provides the updated guidance to NEI 00-02 to be commensurate the ASME/ANS PRA standard and addresses internal events and internal floods Level 1/LERF PRA. It is endorsed in RG 1.200.
- NEI 07-12 (published in 2007) provides the peer review guidance for internal fire Level 1/LERF PRA. It is endorsed in RG 1.200.
- NEI 12-13 (published in 2012) provides the peer review guidance for external hazards Level 1/LERF PRA. NRC issued a letter providing comments on the guidance, it has not been endorsed in RG 1.200.
FY 2015
NEI 00-02 – continues to be endorsed in RG 1.200
- NEI 05-04 – continues to be endorsed in RG 1.200
- NEI 07-12 – continues to be endorsed in RG 1.200
- NEI 12-13 – has not been endorsed in RG 1.200
FY 2016
NEI 00-02 – continues to be endorsed in RG 1.200
- NEI 05-04 – continues to be endorsed in RG 1.200
- NEI 07-12 – continues to be endorsed in RG 1.200
- NEI 12-13 – has not been endorsed in RG 1.200
FY 2017
NEI 00-02 – continues to be endorsed in RG 1.200
- NEI 05-04 – continues to be endorsed in RG 1.200
- NEI 07-12 – continues to be endorsed in RG 1.200
- NEI 12-13 – has not been endorsed in RG 1.200
- NRC developed draft comments on NEI 12-13 (for staff approval) and planned to request external stakeholder feedback
- Appendix "x" – The staff continued to observe uses of the appendix. The staff issued a letter providing interim approval of the process given certain staff comments were addressed. This appendix has not yet been endorsed in RG 1.200.
- NEI informed the staff of their intention to develop guidance, "Performance of PRA Peer Reviews Using the ASME/ANS PRA Standard." This guidance document is meant to replace the previous individual guidance documents.
Risk-Informed Basis
Under this activity the infrastructure is developed to support risk-informed decision-making. The purpose of this activity is to provide the agency position on an acceptable base PRA such that the results from the PRA can be used in risk-informed decision-making.
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Risk-Informed Steering Committee (RISC)
Summary Description
The NRC's RISC was established in 2014 to provide strategic direction to the NRC staff to advance the use of risk-informed decision making (RIDM) in various NRC activities, consistent with the Commission's Probabilistic Risk Assessment (PRA) Policy Statement. The NRC's RISC comprises of a senior management committee representing the NRC program offices (NRR, NRO, RES, NMSS, and NSIR as well as a senior executive from a regional office). The RISC is chaired by the NRR Office Director.
The objectives of the RISC include engaging the industry relative to the use of PRA to support regulatory decision-making, discussion of NRC driven initiatives that incentivize industry to continue to develop PRAs thereby providing a framework to make decisions in light of inherent uncertainty in PRA models, and discussion of industry actions necessary to achieve the vision of future use of PRA to support regulatory decisions. Recently, in response to comments from the Advisory Committee on Reactor Safety (ACRS) on SECY-15-0168, the NRC staff agreed with the ACRS's view that continued enhancements to the usage of risk-informed regulatory approaches should be pursued in future regulatory activities and stated that NRC activities in this and related areas will be overseen by NRC's RISC committee.
The NRC RISC regularly interfaces with its industry counterpart which comprises of licensee chief nuclear officers, senior level executives, and representation from the Nuclear Energy Institute (NEI). At the time NRC's RISC was formed in 2014, technical adequacy and uncertainties in risk-informed decision making were areas of focus. Technical adequacy was viewed as a solution to some of the PRA quality issues that arose in NFPA-805 reviews and the second issue stemmed from the aggregation of core damage frequency contributions from multiple initiators. Consequently, the NRC and industry each agreed to form two working groups; one focused on technical adequacy of PRAs and the other focused on treatment of uncertainty in RIDM. The NRC RISC, to address its objectives, has undertaken several activities in recent years under the auspices of these two working groups. Additional information is available.
FY 2015
The NRC RISC held multiple public meetings with the industry RISC to receive updates on the working groups' status and to discuss other risk-informed initiatives. The industry working groups developed white papers outlining gaps in current processes and the actions to close those gaps. The NRC held public meetings to discuss the review of the white papers and provided comments to the industry. The NRC working groups will each issue a memorandum to the RISC with recommended actions to close gaps identified in the white papers. The actions will be completed by the appropriate line organization in accordance with normal work practices. The staff has developed plans and continued work on the related initiatives by scheduling a public workshop on NUREG-1855 and a public meeting to seek input on how to treat the industry developed, and NRC endorsed, Flex strategies and equipment in risk-informed decision-making. The NRC RISC will continue to hold public meetings with the industry RISC to discuss current and upcoming risk-informed initiatives of interest.
FY 2016
The NRC RISC held multiple public meetings with the industry RISC to receive updates on the working group's status and to discuss other risk informed initiatives. The NRC RISC working group held a public workshop to discuss draft guidance documents from the industry on the topic of a proposed approach to close out the comments generated by a peer-review of the licensee's PRA model. The NRC staff also observed an industry pilot project to implement the proposed approach and derive lessons learned for future discussions on the topic. NRC staff held a public meeting to discuss the new approach, termed the vetting panel process, proposed by the RISC's technical adequacy working group to determine the technical adequacy of a new PRA methods. The staff is currently developing internal guidance for the implementation of the proposed approach. These initiatives are expected to improve the staff's efficiency in the review of future risk-informed licensing actions. The NRC RISC engaged the industry in activities related to crediting FLEX/mitigating strategies (MS) equipment in RIDM. The industry developed white papers and held a workshop with good participation from both industry and the NRC. The white papers were found to address a large number of issues that are important to the NRC staff in RIDM. The industry revised the white papers based on NRC staff comments. The staff plans to update internal guidance for considering credited FLEX/MS equipment during the review of risk-informed licensing applications.
In addition, NRC has held public meetings to seek stakeholder input on the update on NUREG-1855, "Guidance on the Treatment of Uncertainties Associated with PRAs in Risk-Informed Decision Making". As a result of the interaction at the public meetings, NRC is currently developing training related to the treatment of uncertainties in RIDM.
The NRC RISC directed the evaluation of the use of licensee PRA models in regulatory applications where SPAR models are currently being utilized. This evaluation was intended to evaluate the potential benefits, pitfalls, and cost of shifting to this approach. Ultimately, it was revealed that while there may have been some incremental cost savings after a full implementation period, the risk to the Agency of pursuing this initiative was too great to justify continued evaluation at this time. The NRC RISC will continue to hold public meetings with the industry RISC to discuss current and upcoming risk-informed initiatives of interest.
FY 2017
The NRC and industry RISCs held multiple public meetings to discuss a number of activities important to NRC's RISC or industry's RISC. The key issues discussed at the FY 2017 meetings were Technical Specification (TS) Initiative 4B, the peer review Facts and Observations (F&O) closure process, risk-informed categorization and treatment of SSCs for nuclear power reactors (10 CFR 50.69), diverse and flexible coping strategies (FLEX) in risk-informed decision making (RIDM), Fire PRA realism, PRA methods vetting process, realism in the reactor oversight process (ROP), and Risk Aggregation. Some highlights of these risk informed initiates are provided below:
- TS Initiative 4B: The NRC staff issued its amendment to implement TS Initiative 4B for the pilot plant in August 2017. The NRC is developing a revised version of TSTF-505 which the licensee will use in support of Tech Spec 4B. The revised TSTF-505 is less complex but more restrictive than the approved pilot's TS Initiative 4B program.
- Facts and Observations (F&O) closure process: The NRC staff provided a letter dated May 3, 2017, accepting industry's guidance on the F&O independent assessment process (ADAMS Accession No. ML1707A427). The staff plans to incorporate its expectations for closure of F&Os as a staff regulatory position in the next update to RG 1.200, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities." The staff regulatory position will be used as the basis for endorsement of NEI's guidance for the F&O independent assessment process.
- 10 CFR 50.69: The NRC informed industry that is has resources to review 10 license amendment applications per year. The staff believes that the facts and observations (F&O) closure process will result in more efficient licensing reviews. The NRC completed the pilot license amendment request (LAR) for this initiative.
- FLEX in RIDM: FLEX is currently being credited in multiple-risk applications. The NRC staff has developed several guidance documents to promote consistency and efficiency in applications in these areas. The staff is continuing to monitor the licensees' use of FLEX and is evaluating the need for additional guidance changes.
- Fire PRA Realism: The NRC's Office of Nuclear Regulatory Research (RES) is working closely with EPRI to address a number of areas to improve the level of realism in fire PRA. This effort encompasses topics such as main control room abandonment, heat release rates, fire ignition frequencies, fire growth rate assumptions, and the potential influence of aluminum in high-energy arcing faults. Industry and the NRC are discussing the most effective means to update the NUREG/CR-6850 methodology.
- PRA Methods Vetting process: In April 2017, the staff approved a fee waiver to industry to permit the piloting of three new PRA methods through the vetting panel process. In June 2017, the staff and industry discussed and agreed on changes to draft NEI 16-04 that would guide the pilot actions for the vetting panel process.
- Realism in the ROP: On March 21, 2017 NRC transmitted their plan to address industry concerns for the treatment of Common Cause Failures (CCF), the treatment of dependency between human errors in accident sequences, and the methods used to model various performance deficiencies. Several public meetings have been held to move forward on these topics. The industry has proposed that pursuing the CCF issue is the highest priority.
- Risk Aggregation: The staff has prepared training material for NUREG 1855, Revision 1 that will discuss uncertainty and decision-making in risk-informed applications. The upcoming revision to RG 1.174 in March 2018 will expand the explanations and definitions of deterministic consideration, which will help when making risk-informed licensing decisions. EPRI has published a report that provides its approach for addressing risk aggregation (EPRI Report 3002003116). At this time, the Pressurized-Water Reactor Owners Group is in the process of piloting this framework.
The RISC will be continuing to meet and discuss the current and upcoming risk-informed initiatives to provide the strategic direction to advance the risk-informed decision making in NRC activities.
Risk-Informed Basis
The RISC engages the industry and addresses concerns relative to the use of PRA to support regulatory decision-making. The RISC provides strategic direction to the NRC staff by using a holistic, risk-informed, approach to decision making.
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NRC "Grow Your Own" PRA Capability
Summary Description
This NRC-wide PRA "Grow Your Own" (GYO) program was established to provide less experienced staff with high technical potential, the opportunity to have a focused, hands-on experience with risk-informed regulations, licensing actions, and decision-making. At the completion of the 3-year GYO program, those staff that pass their technical boards are recognized as reliability and risk analysts at the GG-14 level or promoted if at a lower grade.
FY 2015 Status
The initial two staff members in the program within the Office of New Reactors (NRO) and three staff members within the Office of Nuclear Reactor Regulation (NRR) completed all their required activities and passed their technical boards in the summer of 2015.
FY 2016 Status
The NRC continues to provide staff training on various aspects of PRA including use of the agency risk models/software and their application to analyze events and Licensee applications. The agency graduated 1 employees this year and currently has 8 program participants projected to graduate soon.
FY 2017 Status
Six additional staff members in the program within the Office of Nuclear Reactor Regulation (NRR) have completed their required activities and qualified by passing their technical boards in April and May 2017. Two additional staff members are projected to graduate in the third quarter of FY 2018 from within the Office of Nuclear Reactor Regulation (NRR).
Risk-Informed Basis
Enhancing the PRA knowledge and capability of NRC staff supports the application of risk-informed decision-making.
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Update Regulatory Guide 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant Specific Changes to the Licensing Basis
Summary Description
As directed by the Commission in SRM SECY 11 0014, Regulatory Guide (RG) 1.174 is being revised to assure consistent interpretation and implementation of the defense-in-depth philosophy. RG 1.174 provides guidance on the use of PRA findings and risk insights to support licensee requests for changes to a plant's licensing basis, as in requests for license amendments and technical specification changes under Title 10 of the Code of Federal Regulations (10 CFR) Sections 50.90, "Application for Amendment of License, Construction Permit, or Early Site Permit," and 50.92, "Issuance of Amendment."
FY 2015 Status
The current status of this activity remains unchanged from the previous risk-informed activities update. Additional information is available.
FY 2016 Status
During this fiscal year, the staff continued to meet with internal and external stakeholders to solicit their input into the update of RG 1.174. The focus of this activity is a review and update of RG 1.174 and other related guidance documents (e.g., RGs 1.175, 1.177, and 1.178) to clarify the staff position on how the defense-in-depth principles of the integrated risk-informed decision-making process are addressed in the review of a licensee's request to change its licensing basis.
FY 2017 Status
During this fiscal year, the staff continued revising the defense-in-depth guidance and soliciting input from internal and external stakeholders, including feedback from the Advisory Committee on Reactor Safeguards (ACRS) Subcommittee on Reliability and PRA. The staff published for public review and comment an update of the draft regulatory guide for Revision 3 of RG 1.174 (i.e., DG 1285). The staff resolved all internal and external stakeholder comments on DG-1285 and prepared to meet with and receive feedback from the ACRS Full Committee on the final draft of the revised RG.
Risk-Informed Basis
RG 1.174 describes an acceptable approach for assessing the nature and impact of proposed licensing basis changes by considering engineering issues and applying risk insights. The intent of the assessment is to demonstrate the proposed licensing basis changes will only result in small increases in risk and only when it is also reasonably assured that, among other things, consistency with the defense-in-depth philosophy and sufficient safety margins are maintained.
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Update NUREG 1855, Guidance on the Treatment of Uncertainties Associated with PRAs in Risk-Informed Decisionmaking
Summary Description
This document provides guidance on how to treat uncertainties associated with PRA in risk-informed decision-making with regard to: 1) Identifying and characterizing the uncertainties associated with PRA in support of the PRA standard, 2) Performing uncertainty analyses to understand the impact of the uncertainties on the results of the PRA, and 3) Factoring the results of the uncertainty analyses into decision-making. This NUREG also provides guidance on how to meet the ASME/ANS PRA standard requirements for addressing uncertainties in the PRA model. NRC recognized that the Electric Power Research Institute (EPRI) also was performing work in this area with similar objectives. Both NRC and EPRI believed a collaborative effort to have technical agreement and to minimize duplication of effort would be more effective and efficient.
FY 2015
Revision to the document is under review.
FY 2016
A public workshop was held to "pilot" the Revision 1 draft and finalize for publication.
FY 2017
The staff published Revision 1 to the NUREG. The revision provided additional text to further clarify the guidance and the relationship to the associated EPRI documents. In addition, the staff developed a Web-based training course for both internal and external stakeholders. The course is designed for both staff and management. It teaches the concepts used in the guidance for treating PRA uncertainties in risk-informed decisionmaking. The course has options that allows the user to take a shorter version of the course or go into more detail.
Risk-Informed Basis
NUREG-1855 helps the decision maker understand to what extent the risk results are impacted by the uncertainties, understand whether there are risk results that may challenge the risk acceptance guidelines, and to determine if the driver for the large uncertainties can be identified and remediated.
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