HomeAbout NRCHow We RegulateRisk AssessmentCurrent Risk-Informed Activities

# 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 (using *expanding menus*):
            - Consideration of Safety Significance in Addressing NMSS Licensing Basis and Potential Violation Questions
            - Rulemaking Activities
            - RG 1.200, Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities (LWRs)
            - PRA Standards Development
            - Industry Peer Review Guidance Development
            - Risk-Informed Steering Committee (RISC)
            - Regulatory Guide 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant Specific Changes to the Licensing Basis
            - NUREG 1855, Guidance on the Treatment of Uncertainties Associated with PRAs in Risk-Informed Decisionmaking
            - Achieving the Vision of Becoming a Modern, Risk-Informed Regulator
            - Regulatory Improvements for Production and Utilization Facilities Transitioning to Decommissioning Rulemaking

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## Consideration of Safety Significance in Addressing NMSS Licensing Basis and Potential Violation Questions

**Summary Description**

**Summary Description**
The Office of Nuclear Material Safety and Safeguards (NMSS) regulates byproduct material use, fuel cycle facilities, storage and transport of spent fuel, decommissioning of nuclear facilities, and low-level waste disposal.  NMSS is exploring how it can enhance existing processes and procedures to better focus regulatory attention on design and operational questions in all these areas commensurate with their importance to health and safety and common defense and security.  This effort, which follows a similar activity in NRR, is sometimes referred to as the Low Safety Significance Issue Resolution process.  It utilizes quantitative and qualitative risk insights; recognizing that most aspects of the materials arena do not fully use quantitative risk models. However, risk insights are derived by progressive screening questions up to, and including, qualitative-quantitative estimations based on operational experience and expert judgment using the risk triplet (i.e., What can go wrong?  How likely is it?  What are the consequences?). This ensures that questions and issues potentially impacting safety are promptly identified, 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 facility or activity licensing basis resulting in questions regarding 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 can be resource intensive, inefficient, and untimely in many cases.

The Technical Assistance Request (TAR) process is often the means by which assistance in addressing the above type questions is provided and is routinely used to address unresolved questions from the NRC Regional Offices.  For some licensing basis issues, past experience reveals an imbalanced expenditure of time, resources, and effort compared to the underlying issue's significance to health and safety, and common defense and security.  In addition to improving the screening process within the inspection procedures to allow the consideration of safety significance in the light of a question on the licensing basis, the TAR process is currently being enhanced to include similar guidance.

**Previous Fiscal Years**

**Previous Fiscal Years**
**FY 2020**

Work initially focused on enhancing the TAR process to identify and screen issues that are determined to be of very low safety significance using a progressive screening approach that relies on operating experience and expert judgment in addressing the risk triplet. In the second half of the fiscal year, the effort expanded to enhancing aspects of issue screening process within the inspection guidance. The draft TAR process has been internally reviewed within NMSS and the Regions and insights from those reviews indicated the need for additional clarity in the new risk-informed aspects of the procedure. The draft TAR is currently being revised. In addition, an NMSS working group has been formed to leverage the insights and approaches being pursued to ensure consistency and identify technical or regulatory reasons for differences based on the nuclear materials functional areas. External stakeholder engagement is planned for early FY 2021 to gain stakeholder feedback on this initiative.

**FY 2021**

During the past year the working group continued to refine the approach and an example past fuel cycle inspection issue was used to explore additional insights and improvements in the qualitative/semi-quantitative issue screening process. During the fall an additional issue was identified for low level waste that demonstrated how the risk triplet/BeRiskSMART approach could be used in identifying the appropriate options to consider when addressing an issue involving the interface between the inspection and licensing paradigms. As issues arise, the working group will continue to refine and further develop the approach and technical bases behind the process.

**FY 2022**

No update.

**FY 2023**
No update.

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## Rulemaking Activities

For more information see NRC Rules and Petitions website.

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## RG 1.200, Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities (LWRs)

For more information see public web page: Risk-Informed Activities Technical Guidance Program.

**FY 2023**
In FY2023, the staff began review of a new revision of the PRA standard for light-water reactors (LWRs) for endorsement in the next revision of RG 1.200. The staff’s plan for the next revision of RG 1.200 and endorsement of new PRA standards was presented at a public meeting on May 2, 2023. The staff will continue to engage with the public as the revision of RG 1.200 progresses.

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## PRA Standards Development

For more information see public web page: Risk-Informed Activities Technical Guidance Program.

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## Industry Peer Review Guidance Development

For more information see public web page: Risk-Informed Activities Technical Guidance Program.

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## Risk-Informed Steering Committee (RISC)

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 comprised 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 was chaired by the NRR Office Director.

The objectives of the RISC were to engage 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.

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.

In 2019, under the direction of the NRR Office Director, internal NRC RISC meetings were suspended as other initiatives had taken over the role of promoting risk insights in NRC activities. NRR has leveraged several other venues to communicate ongoing and future risk initiatives, internally within the agency, as well as externally with NEI, industry and the public. As such, the RISC evolved into a single entity driven by NRR and the Division of Risk Assessment to focus solely on addressing specific licensing issues (i.e., PRA tools and methods) at operating reactors. It was decided that the RISC would meet on an as needed basis and at present there are no initiatives being undertaken by the RISC.

**Previous Fiscal Years**

**Previous Fiscal Years**
**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 it 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.

**FY 2018**

The NRC and industry RISCs held multiple public meetings to discuss a number of activities important to NRC's RISC or industry's RISC as well as to discuss the charter to provide a better focus on strategic issues that should require the purview of senior management as opposed to number of lower-tier implementation items. The key issues discussed at the FY 2018 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, and realism in the reactor oversight process (ROP). 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. The NRC staff is reviewing for additional license amendment requests
              - 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). In 2018, the staff conducted a number of audits to ensure that licensees appropriately followed the independent assessment process. 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 issues the safety evaluation for Limerick Generating station. Staff is reviewing 12 additional license amendment requests.
              - 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. The staff emphasized the need to receive operational experience on FLEX strategies and enhanced HRA methods to support various applications that can be credited with FLEX strategies.
              - 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. In June 2018, NEI formally informed that they are no longer interested in vetting panel process and provided an alternative for staff consideration.
              - 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.

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. 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.

**FY 2019**

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 2019 meetings were Technical Specification (TS) Initiative 4B, 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, issues relating to High Energy Arcing Faults (HEAF), and the new PRA methods approval process. In each of these areas, senior managers of the industry and NRC discussed status of key projects, challenges, and strategies to overcome those challenges. Consequently, in each of these areas the NRC staff made significant progress while appropriately considering industry concern.

**FY 2020**

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 2020 meetings were Technical Specification (TS) Initiative 4B, 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, issues relating to High Energy Arcing Faults (HEAF), the new PRA methods approval process, and the Risk-Informed Process for Evaluations as part of LSSIR. In each of these areas, senior managers of the industry and NRC discussed status of key projects, challenges, and strategies to overcome those challenges. Consequently, in each of these areas the NRC staff made significant progress while appropriately considering industry concerns.

**FY 2021**

On June 22, 2021, the NRC industry RISC held a virtual meeting. The issues discussed at the FY 2021 meetings from NRC were from updates to High Energy Arcing Faults (HEAF), and PRA Configuration Control. Industry discussed Expanded Integration of FLEX and relation to the Duane Arnold derecho event. Finally future RISC focus areas were also discussed with specific mentions of risk-informing 50.59 screenings, ultimate heat sink technical specification limits, risk-informing the review of topical reports and emergency planning zones.

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## Regulatory Guide 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant Specific Changes to the Licensing Basis

For more information see public web page: Risk-Informed Activities Technical Guidance Program.

 |  

## NUREG 1855, Guidance on the Treatment of Uncertainties Associated with PRAs in Risk-Informed Decisionmaking

For more information see public web page: Risk-Informed Activities Technical Guidance Program.

**FY 2023**
In FY2023, the staff initiated work to revise NUREG-1855 to incorporate updated guidance and address NRC endorsement of new PRA standards. The staff will engage with public on the updated guidance as the work on the NUREG-1855 revision progresses.

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## Achieving the Vision of Becoming a Modern, Risk-Informed Regulator

For more information see existing Modern Risk-Informed Regulator website.

**FY 2023**
On March 14, 2023, NRC issued Information Notice (IN) 2023-01, "Risk Insights from High Energy Arcing Fault Operating Experience and Analyses." The Information Notice is available and more details regarding the significant body of work related to high energy arcing faults can be found on the NRC’s High Energy Arc Faut (HEAF) research website.

On October 10, the staff issued Regulatory Guide (RG) 1.183 Revision 1, "Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors." NRR is the technical lead for RG 1.183, Revision 1, which incorporates new technical methods and lessons learned since RG 1.183, Revision 0, was originally published. RG 1.183, Revision 1, addresses one of the high priorities listed in the agency’s accident tolerant fuel roadmap and includes the scope, and documentation of associated analyses and evaluations; consideration of impacts on analyzed risk; and content of submittals as well as guidance associated with the licensing of advanced light water reactors and other industry initiatives, such as high-burnup and increased enrichment. The staff will be pursuing another revision of this RG to support the increased enrichment rulemaking.

In an effort to address a gap in the oversight process associated with PRA Configuration Control, the staff successfully identified a balanced and performance-based approach to address this issue by leveraging the OpE smart sample process. On November 14, 2023, the NRC issued the draft Operating Experience Smart Sample on PRA Configuration Control as a publicly available document. The staff has been communicating with external stakeholders, including industry, at several public meetings on the status of this initiative. The final Smart Sample will be issued in early 2024 and is planned for implementation by Q3 of 2024.

By letter dated December 13,2023, the Nuclear Regulatory Commission authorized the proposed alternative to the requirements of American Society of Mechanical Engineers (ASME), Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components" for Oconee Nuclear Station (ONS),Units 1, 2, and 3, and Keowee Hydro Station, Units 1 and 2. Specifically, Duke Energy requested to use Code Case N-752, "Risk-Informed Categorization and Treatment for Repair/Replacement Activities in Class 2 and 3 Systems Section XI, Division 1," for determining the risk-informed categorization and for implementing alternative treatment for repair/replacement activities on moderate and high energy Class 2 and 3 items in lieu of certain ASME Code Section XI, paragraph IWA-1000, IWA-4000, and IWA-6000 requirements. Duke Energy submitted the request pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a "Codes and Standards," on the basis that the proposed alternative would provide an acceptable level of quality and safety in accordance with 10 CFR 50.55a(z)(1). Code Case N-752 has not been approved by the NRC or incorporated by reference for generic use. Therefore, the NRC reviewed the Duke Energy submittal as a plant-specific request for Oconee. Additionally, several other licensees have either submitted or plan to request a site- specific alternative to adopt Code Case N-752.

On September 12, 2023, NRR staff hosted NRC’s 2023 Risk Forum. Over 400 stakeholders participated in the meeting, including experts from across the NRC, the National Aeronautics and Space Administration (NASA), the Federal Aviation Administration (FAA), and multiple industry groups and utilities. An especially engaging discussion regarding the incorporation of RIDM into an organization’s culture highlighted that the industry, NASA, FAA, and the NRC share similar challenges in incorporating RIDM. Stakeholders also highlighted the successes of leveraging RIDM to make safety improvements at nuclear power plants; explored the many facets of managing the various kinds of uncertainty; and applying risk-informed principles to the licensing of operating, new, and advanced reactors.

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## Regulatory Improvements for Production and Utilization Facilities Transitioning to Decommissioning Rulemaking

For more information see Planned Rulemaking Activities - Rule website.

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Page Last Reviewed/Updated Wednesday, February 21, 2024

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