Advanced Reactors Sub-Arena
Advanced reactors comprise 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 this sub-arena:
Develop a coherent risk-informed and performance-based regulatory structure for design certification, licensing, and oversight of advanced reactors.
A coherent risk-informed and performance-based regulatory structure would offer significant improvements in effectiveness and efficiency (compared to the structure that has evolved for current-generation LWRs). For example, such coherence would ensure that the safety reviews conducted by the NRC consider design and operational aspects in an integrated manner. The bases for developing such a regulatory structure for licensing and oversight of advanced reactors are articulated in numerous Commission documents and policy statements. However, this guidance occurs largely in the context of existing and new LWRs and, consequently, needs to be adapted for advanced reactors.
The bases for a coherent risk-informed and performance-based regulatory structure arise from the potential to realize benefits that are captured in the screening criteria that the NRC staff considers in undertaking regulatory improvement initiatives:
- Effectiveness: One hallmark of effectiveness is the ability to model the tradeoffs that are involved in a complex safety review. Sometimes, such tradeoffs are represented as the ability to achieve desired outcomes in the licensing process. A risk-informed and performance-based regulatory structure is inherently better able to do this, especially if it is applied in the early phases of developing a new regulatory structure for advanced reactors.
- Effective Communication: The explicit modeling of decision-making promotes transparency. Sometimes, the traditional prescriptive regulatory structure lacks transparency because it tends to emphasize compliance with a prescribed quantity, rather than focusing on the safety function.
- Research: The NRC staff has conducted significant research into the models and methodologies for the risk-informed and performance-based regulatory structure and the products and expertise from this work are available for implementation. Particularly notable examples include NUREG-1860, NUREG/BR-0303, and SECY-05-0138. Specific details will need to be determined and guidance developed based on the particular technology and design aspects of the application.
- Costs: The implementation of a coherent risk-informed and performance-based regulatory structure for advanced reactors will entail a combination of short- and long-term costs. The new regulatory approaches are likely to result in short-term costs. However, when considered in the context of implementing the Commission’s strategic objectives, there are sound reasons to expect a significant reduction in the total cost to society.
- Obstacles: There are no apparent factors (e.g., state-of-the-art, adverse stakeholder perception) that would preclude implementing a risk-informed and performance-based approach to the design certification, licensing, and oversight of advanced reactors once sufficient operating experience is available to provide input to the activities.
The NRC developed its strategic planning process as a result of considerable effort (beginning in the late-1990s) to improve the agency’s regulatory structure in a forward-looking way, while preserving the gains that the agency had achieved in operating reactor safety. Using the most recent version of the Strategic Plan, development of a coherent risk-informed and performance-based regulatory structure for advanced reactors will involve implementing the strategies that the Commission articulated in the goal of “Safety”. Under “Safety” strategies, the Commission directed the staff to “Use sound science and state-of-the-art methods to establish, where appropriate, risk-informed and performance-based regulations.” This element continues to be part of the Strategic Plan for the Fiscal Year (FY) 2008–2013.
The basic infrastructure for the implementation of a risk-informed and performance-based approach exists at a high-level in Commission documents, such as the “White Paper on Risk-Informed and Performance-Based Regulation.” The staff has also developed some specific guidance, including the risk-informed process for implementing the single-failure criterion (SECY-05-0138), but more may need to be developed. In many instances, the high-level documents superficially apply only to existing LWRs; however, more thorough study reveals considerable applicability to all reactor technologies. For example, the Reactor Oversight Process (SECY-99-007 and SECY-99-007A, as well as related staff requirements memorandum) provides a risk-informed and performance-based structure, although it is overlaid on top of existing LWR requirements.
The staff’s risk-informed and performance-based goals for advanced reactors relate to the following activities:
- Ensure advanced reactor applicants use risk-informed safety insights to select among alternative features, operational strategies, and design options to reduce or eliminate the significant risk contributors of existing operating plants.
- Ensure that the risk associated with advanced reactor designs compare favorably with the Commission’s goals of less than 1E-04/year for core damage frequency and less than 1E-06/year for large release frequency
Risk-Informed and Performance-Based Activities
The following table specifies the ongoing rulemaking 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 Advanced Reactors Sub-Arena within the Reactor Safety Arena.
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|Initiative, Program or Project||Project Description and Major Activities||Status
|Pre-application review for Next Generation Nuclear Plant (NGNP): As part of the implementation of the NGNP licensing strategy, review white papers submitted by the NGNP project related to various licensing issues, including the use of risk-informed approaches.||The NRC staff has reviewed NGNP-related white papers from a risk-informed and performance-based perspective. These papers addressed the approach on such topics as probabilistic risk assessment (PRA); selection of licensing-basis events (LBE); classification of structures, systems, and components (SSCs); and defense-in-depth.
Risk Basis: The documents submitted for review proposed a risk-informed and performance based licensing approach.
|NRC's staff review of the documents is complete and staff recommendations have been discussed with the ACRS and with DOE. Final staff reports will be approved by November-2013.|
|Pre-application review for SMR designs: Develop a framework, implementation strategy, and plans and schedules to more fully integrate the use of risk insights into pre-application activities and the review of small modular reactor (SMR) applications.||
The NRC staff has developed risk-informed, integrated review framework incorporating performance-based approaches to better align review resources with SSC safety and risk significance, consistent with regulatory requirements. The framework will be available for pre-application and post-application activities for light-water SMR licensing actions submitted under 10 CFR Part 52. Participation in the framework by applicants is optional and the requirements for applicants and applications are not changed.
As part of the framework, the staff will develop Design Specific Review Standards (DSRSs) for use with designs by applicants that choose to engage the NRC in pre-application activities. The staff has developed a DSRS for the mPower(tm) design and is currently preparing another DSRS for the NuScale design.
Risk Basis: The staff will develop and implement a risk informed and performance based review framework consistent with existing regulations.
Staff issued SECY 11-0024 (2/18/2011) to address this issue and the Commission issued an SRM dated 5/11/2011 to the staff approving the approach outlined in the SECY.
The staff created NUREG-0800 Standard Review Plan Introduction, Part 2, to describe and implement a risk-informed, integrated review framework for light-water SMRs. The revised SRP has received public comments and the final document is in concurrence.
To request additional information, Contact Us About Risk-Informed, Performance-Based Regulation.