ML21050A351

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Action Plan for Review and Endorsement of Asme/Ans Advanced Non-LWR PRA Standard Asme/Ans RA-S-1.4, Revision 1
ML21050A351
Person / Time
Issue date: 02/19/2021
From: David Williams
NRC/NRR/DANU
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Williams D
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Download: ML21050A351 (21)
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ACTION PLAN REVIEW AND ENDORSEMENT OF ASME/ANS ADVANCED NON-LWR PRA STANDARD ASME/ANS RA-S-1.4 Revision 1 February 19, 2021 Contents

1.0 INTRODUCTION

......................................................................................................... 4 1.1 Background .............................................................................................................. 4 1.2 Objectives ................................................................................................................ 6 1.3 Scope and Limitations ............................................................................................. 7 2.0 APPROACH ................................................................................................................ 7 2.1 Task 1: Supporting Development of the Advanced non-LWR PRA Standard ......... 7 2.2 Task 2: Preparation for Review of the NLWR PRA Standard for Endorsement ..... 8 2.2.1 Task 2-1: Determine the scope of regulatory activities for the NLWR PRA standard.......................................................................................................................... 9 2.2.2 Task 2-2: Identify the needed technical expertise to review the NLWR PRA standard for endorsement .............................................................................................. 9 2.2.3 Task 2-3: Create guidance for staff review of ANLWR PRA standard ........... 10 2.2.4 Task 2-4: Compare the NLWR PRA standard to the LWR PRA standards and RG 1.200 ...................................................................................................................... 10 2.2.5 Task 2-5: Develop staff position for an acceptable NLWR PRA and peer review guidance............................................................................................................ 11 2.2.6 Task 2-6 Identify and resolve technical and policy issues ............................. 13 2.3 Task 3: Staff Review and Endorsement of the NLWR PRA Standard ................. 13 2.3.1 Task 3-1 Develop preliminary trial use regulatory guide................................. 14 2.3.2 Task 3-2 Review NLWR PRA standard for Endorsement .............................. 14 2.3.3 Task 3-3 Publish trial use RG ......................................................................... 15 2.4 Task 4: Development of schedule for Staff Review and Endorsement ................ 16 2.5 Task 5: Development of Communication Plan ..................................................... 19 2.5.1 Communication with internal stakeholders ..................................................... 19 2.5.2 Communication with external stakeholders .................................................... 19

3.0 REFERENCES

.......................................................................................................... 20

1.0 INTRODUCTION

1.1 Background

The U.S. Nuclear Regulatory Commission (NRC), by publishing its Final Policy Statement on the Use of Probabilistic Risk Assessment Methods in Nuclear Regulatory Activities (Ref.

1), reflected its belief that an overall policy on the use of probabilistic risk assessment (PRA) methods in nuclear regulatory activities should be established so that the many potential applications of PRA would be implemented in a consistent and predictable manner that would promote regulatory stability and efficiency. Furthermore, the Commission stated its belief that the use of PRA technology in NRC regulatory activities should be increased to the extent supported by the state-of-the-art in PRA methods and data and in a manner that complements the NRCs deterministic approach. In addition, the Commission published regulations pertaining to design certification (DC) applicants, combined license (COL) applicants, and COL holders as follows:

10 Code of Federal Regulations (CFR) 52.47(a)(27) states that a DC application must contain an FSAR that includes a description of the design-specific PRA and its results.

10 CFR 52.79(a)(46) states that a COL application must contain an FSAR that includes a description of the plant-specific PRA and its results.

10 CFR 52.137(a)(25) states that a standard design approval (SDA) application must contain an FSAR that includes a description of the design-specific PRA and its results.

10 CFR 52.157(a)(31) states that a manufacturing license (ML) application must contain an FSAR that includes a description of the design-specific PRA and its results.

10 CFR 50.71(h)(1) states that no later than the scheduled date for initial loading of fuel, each holder of a COL shall develop a Level 1 and a Level 2 PRA. The PRA must cover those initiating events and modes for which NRC-endorsed consensus standards on PRA exist one year prior to the scheduled date for initial loading of fuel.

10 CFR 50.71(h)(2) states that each COL holder must maintain and upgrade the PRA required by 10 CFR 50.71(h)(1). The upgraded PRA must cover initiating events and modes of operation contained in NRC-endorsed consensus standards on PRA in effect one year prior to each required upgrade. The PRA must be upgraded every four years until the permanent cessation of operations under 10 CFR 52.110(a).

10 CFR 50.71(h)(3) states that each COL holder must, no later than the date on which the licensee submits an application for a renewed license, upgrade the PRA required by 10 CFR 50.71(h)(1) to cover all modes and all initiating events.

Further, in Staff Requirements Memorandum (SRM)-SECY-15-002 (Ref.2), the Commission confirmed that the Commissions guidance given in the Policy Statement on Severe Reactor Accidents Regarding Future Designs and Existing Plants and other Commission direction identified by staff apply to new 10 CFR Part 50 power reactor applications in a manner consistent with 10 CFR Part 52 design and license applications. The Commission also approved revision of the regulations in 10 CFR Part 50 (Ref. 3) for new power reactor applications to more closely align with requirements in 10 CFR Part 52 (Ref. 4),

incorporating the requirements identified by the staff in this paper which would include PRA requirements for new reactor applicants under 10 CFR Part 50 similar to those for 10 CFR Part 52 applicants.

Congress recently passed the Nuclear Energy Innovation and Modernization Act, which states under Title 1, Advanced Nuclear Reactor and User Fees, Section 103(b)(4)(B), the NRC should evaluate options for licensing commercial advanced nuclear reactors including (iii) collaboration with standards-setting organizations to identify specific technical areas for which new or updated standards are needed and providing assistance if appropriate to ensure the new or updated standards are developed and finalized in a timely fashion; (iv) the incorporation of consensus-based codes and standards developed under clause (iii) into the regulatory framework (I) to provide predictability for the regulatory processes of the Commission; and (II) to ensure timely completion of specific licensing actions Since the PRA Policy Statement and the PRA rule for new reactors were issued, a number of risk-informed activities have been undertaken and a number of documents have been written by both the staff and industry that provide guidance on the use of PRA information in the risk-informed reactor regulatory activities, and on PRA acceptability, such as:

  • Consensus PRA standards have been under development by the American Society of Mechanical Engineers (ASME and the American Nuclear Society (ANS). On April 5, 2002, ASME issued its initial PRA standard for a full-power, internal event (excluding internal fire but including internal floods) Level 1 PRA and a limited Level 2 (i.e., large early release frequency (LERF)) PRA for light-water reactors (LWRs),

referred to here as the Level 1/LERF LWR PRA standard (Ref.5). Addenda and revisions to this PRA standard have subsequently been issued such that this PRA standard addresses all hazards. The next major revision of this PRA standard will be designated as ASME/ANS RA-S-1.1.

  • The advanced non-light water reactor (NLWR) PRA standard, ASME/ANS RA-S-1.4-2021 (Ref. 6), Probabilistic Risk Assessment Standard for Advanced Non-Light Water Reactor Nuclear Power Plants, was issued in February 2021 by the American Society of Mechanical Engineers and American Nuclear Society. The scope of this standard addresses Level 1 PRA through Level 3 PRA as well as all hazards and all operating modes. The requirements in this standard cover PRAs performed during design, pre-operational, and post-operational phases.
  • Regulatory Guide (RG) 1.200 (Ref. 8), An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities, was issued in March 2009 as Revision 2. Revision 3 of RG 1.200 is expected to be issued in 2020. RG 1.200 provides the staff position for an acceptable PRA for LWRs and the staff endorsement of the PRA standard for LWRs. This RG is expected to provide the level of confidence of the PRA such that the PRA is demonstrated to be sufficient to support the identified applications. Consequently, an in-depth technical review by NRC staff would not be needed to ensure acceptability of the PRA to support the applications. This RG allows staff members to focus their review on key assumptions and areas identified by peer reviewers as being of concern and relevant to the application. Consequently, RG 1.200 provides for a more focused and consistent review process.

In implementing RG 1.200, a licensee can use a consensus standard (endorsed by the staff) to demonstrate that the PRA under consideration conforms to the staff position, and an independent peer review to demonstrate that the PRA is in conformance with the PRA standard.

  • For NLWRs, as part of the Licensing Modernization Project (LMP), the Nuclear Energy Institute (NEI) has published a draft document titled Risk-Informed Performance-Based Guidance for Non-Light Water Reactor Licensing Basis (NEI 18-04) (Ref.9). This document presents a technology-inclusive, risk-informed, and performance-based (TI-RIPB) process for selection of Licensing Basis Events (LBEs); safety classification of structures, systems, and components (SSCs) and associated risk-informed special treatments; and determination of defense-in depth adequacy for advanced non-LWRs. When using the LMP methodology, it is expected the NLWR PRA Standard will be used to demonstrate the technical acceptability.

As a result of the publication of NEI 18-04, the staff published Draft Guide (DG) 1353 (Ref.10), to endorse NEI-18-04, with clarifications. This draft guide describes the NRCs proposed guidance on using a technology-inclusive, risk-informed and performance-based methodology to inform the content of applications for licenses, certifications, and approvals for NLWRs.

The staff also issued SECY-19-0117, "Technology-Inclusive, Risk-Informed, and Performance-Based Methodology to Inform the Licensing Basis and Content of Applications for Licenses, Certifications, and Approvals for Non-Light-Water Reactors," a notation vote paper that recommends the Commission find that use of the proposed technology-inclusive, risk-informed, and performance-based methodology is a reasonable approach for establishing key parts of the licensing basis for non-LWRs.

1.2 Objectives The objectives of this document are to describe the tasks that are needed to review and endorse the ASME/ANS NLWR PRA standard, ASME/ANS RA-S-1.4-2021 (Ref. 6),

referred to hereafter as the NLWR PRA standard, and the industry peer review guidance.

The plan describes the approach and activities, on the part of both NRC and industry, that are needed to achieve the program objectives. Moreover, a proposed schedule is included along with the needed resources to implement the plan. This action plan is a living document; it will be updated periodically to show progress of the tasks.

1.3 Scope and Limitations This plan addresses development of the staffs position on acceptability of the PRA needed to support current activities related to NLWRs. These activities include applications for a standard DC, COL, standard design approval (SDA), manufacturing license (ML),

construction permit (CP), or operational license (OL), some of which may be submitted in accordance with the LMP, along with pre-operational and post-operational regulatory activities.

The staff review of the NLWR PRA standard considers a base PRA, risk- informed applications, and use of PRA during the licensing stage. In this context, licensing applications (e.g. submitted under 10 CFR Part 52) are different from risk-informed applications.

2.0 APPROACH This section identifies the activities to develop, review and endorse the ASME/ANS NLWR PRA standard. The staff activities involve six major tasks:

  • Task 1: Supporting development of the NLWR PRA standard
  • Task 2: Preparation for review of the NLWR PRA standard for endorsement
  • Task 3: Staff review and endorsement of the NLWR PRA standard
  • Task 4: Development of schedule for staff review and endorsement
  • Task 5: Development of communication plan The details of each task are described below. In performing some of these tasks, the work may be performed using a version of the NLWR PRA standard that has not yet been approved by ANSI. When this occurs, the version being used will be noted and documented.

2.1 Task 1: Supporting Development of the Advanced non-LWR PRA Standard The objective of this task is to participate on the JCNRM for the purposes of developing a consensus PRA standard for NLWRs. 1 A draft version of the NLWR PRA standard was issued for trial use and has been piloted. Lessons learned from the pilots have been addressed. As part of the process of going from a trial use standard to a final ANSI standard, JCNRM major milestones include the following:

1. Final review to resolve outstanding technical issues in the NLWR PRA standard. An NRC working group representative will provide support to this effort. COMPLETE 1

The NRC will support the JCNRMs effort to maintain the NLWR PRA standard via participation in the JCNRM by maintaining awareness of lessons learned and contemplated by the JCNRM. If any of this updated information impacts the staff position (endorsement), the staff may issue a letter or revise the RG.

2. Readiness review to ensure that the NLWR PRA standard is ready for ballot (e.g.,

standard is in compliance with JCNRM rules). A participating NRC staff member will support this effort. COMPLETE

3. Balloting of the NLWR PRA standard by JCNRM and then by both the ASME and ANS Standard boards. Any negative comments received during any of the ballots will also need to be addressed before going to ANSI for final approval. This effort will be led by JCNRM with the NRC review team and NRC representatives to the JCNRM providing comments on the JCNRM ballot. COMPLETE
4. Technical editing of the NLWR PRA standard will be performed to ensure clear and accurate communication of the standard. This effort will be led by JCNRM.

COMPLETE

5. Issuance of the NLWR PRA standard for ANSI public review and comment. These public comments will also need to be addressed. This effort will be led by JCNRM.

COMPLETE

6. Final review to ensure the technical editing did not negatively impact the requirements in the NLWR PRA standard. This effort will be led by JCNRM.

COMPLETE

7. Publication of the ANSI-approved consensus PRA standard for NLWRs.

COMPLETE 2.2 Task 2: Preparation for Review of the NLWR PRA Standard for Endorsement Work needs to be accomplished before the staff can initiate the review of the NLWR PRA standard. In order for staff to review and endorse the NLWR PRA standard in an efficient and effective manner, the NRC must have a sound understanding of how the NLWR PRA standard was developed and how this standard is to be used. This work includes the following subtasks:

  • Subtask 2-1: Determine the scope of regulatory activities for the NLWR PRA standard. COMPLETE
  • Subtask 2-2: Identify the needed technical expertise to review the NLWR PRA standard for endorsement. COMPLETE
  • Subtask 2-3: Create guidance for staff review of the NLWR PRA standard for endorsement
  • Subtask-2-5: Develop the staff position for an acceptable NLWR PRA
  • Subtask 2-6: Identify and resolve technical and policy issues The objective of each sub-task and how it will be accomplished are described below.

These tasks can be performed in parallel with Task 1.

2.2.1 Task 2-1: Determine the scope of regulatory activities for the NLWR PRA standard The objective of this task is to identify the different applications and associated regulatory activities that will be supported by the NLWR PRA standard. The various applications should address each phase of the facility (i.e., licensing, construction, and operation). As part of this identification, the needed capability of the PRA for each application (and its associated activities) is identified, and therefore, the needed capability and scope from the NLWR PRA standard. An understanding of the different applications (and their associated activities) and their needed capability will determine the level of review and endorsement needed for the NLWR PRA standard.

The capability of the application, and therefore the PRA, is determined by three attributes:

1. Scope and level of detail - The degree to which the scope and level of detail of the plant design, operation, maintenance, and physical phenomena relevant to the plant design are modeled.
2. Plant specificity - The degree to which plant-specific or design-specific information is incorporated such that the as-built and as-operated plant, or as-designed plant, is addressed.
3. Realism - The degree to which realism is incorporated such that the expected response of the plant is addressed.

The degree to which each of the above attributes are addressed determines the capability category (CC). In general, CC I for each attribute is less rigorous (see Table 1.4-2 in the NLWR PRA standard) than CC II; that is, for CC II, the scope and level of detail is generally more expanded, more plant specific information is required, and the level of realism is higher.

This effort will involve identifying and describing each type of application for the various facility stages (e.g., licensing, construction, and operation) along with their associated activities. For each application identified, the capability category will also be identified, that is, whether, in general, the supporting requirements (SRs) need to be CC I or CC II. This identification is performed for a full-scope PRA (i.e., all stages of sequences from initiator to consequence, all operating modes, and all hazards). The results of this task will be documented in the guidance developed in Task 2-3.

2.2.2 Task 2-2: Identify the needed technical expertise to review the NLWR PRA standard for endorsement The objective of this task is to identify the needed technical expertise to review the NLWR PRA standard. The NLWR PRA standard covers multiple technical disciplines. It is necessary to both understand the needed technical expertise and where that expertise should be applied for the review of the NLWR PRA standard. This task will assist in determining whether adequate expertise is available to perform the review and endorsement within the staff.

This effort involves reviewing each scope item (i.e., each stage of sequences from initiator to consequence, each operating mode, and each hazard) and its technical elements to identify the needed technical expertise. Some technical elements are the same regardless of the risk level, hazard, or operating mode. If the technical expertise needs to be modified for a technical element because of the risk, hazard, or operating mode, this should be identified.

2.2.3 Task 2-3: Create guidance for staff review of NLWR PRA standard The objective of this task is to develop the guidance for reviewing the NLWR PRA standard for endorsement. Reviewing the standard will be performed by multiple individuals; it is important that the reviews are performed such that the level of review is consistent.

This effort involves developing the guidelines and criteria that will be used by the individual reviewers. This guidance states that the technical requirements need to meet the staff position and that the NLWR PRA standard also adheres to standards language and other appropriate standard rules. This effort serves as guidance for other tasks. As needed, training will be provided to reviewers on the different types of NLWR applications.

The product of this effort may be a revision to the report describing the guidance and criteria to be used by the staff and its contractors in reviewing the NLWR PRA standard.

The previous version of this report was issued in August 2019 (Ref.11). Alternatively, the staff may develop a new document to guide the reviewers in writing the staff endorsement.

2.2.4 Task 2-4: Compare the NLWR PRA standard to the LWR PRA standards and RG 1.200 The objective of this task is to understand the differences and similarities between the NLWR and the LWR PRA standards and the staff endorsement in RG 1.200. The ASME/ANS Level 1/LERF LWR PRA (ASME/ANS RA-Sa-2009) (Ref. 5) standard has been extensively used for over a decade and the requirements are well understood; however, comparable experience is not available for advanced non-LWRs. Moreover, the advanced non-LWR PRA standard was developed based on requirements in the LWR PRA standards (i.e., the ASME/ANS Level 1/LERF, Level 2, Level 3, and low-power and shutdown (LPSD)

PRA standards), and some of these LWR PRA standards have not been endorsed by the NRC. Further, trial-use versions of some of the LWR PRA standards were used to develop the NLWR PRA standard as they were the only versions of those LWR PRA standards available at the time. A comparison to the established PRA standards is a critical step in establishing the credibility of the NLWR PRA standard.

To that end, the NRC is in the process of developing a PRA standards comparison database that is expected to allow for quick retrieval and display of a given requirement in the NLWR PRA standard, the related requirements from LWR PRA standards upon which it is based (if that is the case), and objective comparisons of the NLWR and LWR PRA standards requirements. In addition, in cases where there is a published NRC endorsement of a requirement from a source LWR PRA standard, the database would include that endorsement as well as a characterization of the applicability of that endorsement to any changes in the related requirement (e.g., changes to a Level 1/LERF PRA standard requirement from 2009 to 2020). The development and construction of the PRA standards comparison database is being supported by NRC contractors from Sandia National Laboratories (SNL)

Understanding the context of an SR is important, particularly since the NLWR PRA standard is expected to adopt SRs from the LWR PRA standards. Therefore, when an SR from an LWR PRA standard is adopted in the NLWR PRA standard, it must be determined that the context is appropriate.

In Task 2-3, the staff will use the results of this comparison to aid in their understanding of the differences between the NLWR PRA standard and the LWR PRA standards. This effort involves comparing the requirements in the NLWR PRA standard to related requirements in the LWR PRA standards. This comparison will identify:

  • where the requirements are similar and consider whether this similarity is appropriate
  • where the requirements are different and consider whether the difference is appropriate
  • where there are requirements in the advanced non-LWR PRA standard that are not in the LWR PRA standard and consider whether this gap is appropriate
  • where there are requirements in the LWR PRA standards that are not in the NLWR PRA standard and consider whether this gap is appropriate.

This comparison is to be done for the entire scope of the NLWR PRA standard. The results of this comparison will help the staff in Task 3 when reviewing the NLWR PRA standard for endorsement.

2.2.5 Task 2-5: Develop staff position for an acceptable NLWR PRA and peer review guidance The objective of this task is to develop the staff position for an acceptable NLWR PRA. The staff position provides the technical basis for reviewing and endorsing the NLWR PRA standard. A staff position is developed for a full-scope PRA addressing all stages of sequences from initiator to consequence, all operating modes, and all hazards for the different types of applications and their associated activities.

This effort involves defining, for the scope identified in Task 2-1, the objectives for each technical element (identified in Task 2-4). The technical attributes and characteristics needed to accomplish the objectives of the technical elements are then developed. In developing the staff position, the various applications (and their associated activities) need to be considered; that is, the staff position for an acceptable PRA may vary depending on the application and its associated activities.

The NLWR PRA standard provides requirements into what constitutes an acceptable base PRA. It does not provide requirements into how to perform such a PRA. To determine that the intents of the various requirements are correctly performed, a peer review of the PRA is required. Consequently, this effort also involves determining the staff position on an acceptable peer review process. NEI submitted NEI 20-09 Performance of PRA Peer Reviews Using the ASME/ANS Advanced Non-LWR PRA Standard which provides guidance for conducting and documenting a Probabilistic Risk Assessment (PRA) peer review using the American Society of Mechanical Engineers (ASME)/American Nuclear Society (ANS) Advanced Non-LWR PRA Standard (ASME/ANS RA-S-1.4-2020). The staff will include its assessment of NEI 20-09 as part of its endorsement of the NLWR PRA standard.

The staff position should cover:

  • An acceptable peer review process, including peer review of newly developed methods
  • Resolution of facts and observations (F&O)
  • Peer review team qualifications
  • Peer review process documentation The staff position should be informed by the staff position in RG 1.200 and modified as needed. This modification may involve revising, adding, or deleting attributes/characteristics.

The NRC staff position on NLWR PRA acceptability describes the fundamental characteristics and attributes necessary to achieve an acceptable PRA and is applicable regardless of whether a national consensus PRA standard is available. As such, the staff position on NLWR PRA acceptability can be developed irrespective of the availability of the NLWR PRA standard.

The product of this effort includes a table (see Table 2-2 below) that identifies the necessary technical attributes and characteristics for an acceptable PRA for an NLWR for the specified scope. The table differentiates the staff position for the different types of applications and activities. Another table (see Table 2-3 below) is developed to include the necessary attributes and characteristics for an acceptable peer review.

Table 2-2 Staff Position of an Acceptable NLWR PRA Hazard Technical Element Technical Attributes and Characteristics Considering the Different Applications/Activities In the first column, for the specific scope, the hazard under consideration is identified. In the second column, for the specified hazard the technical element is provided with a short description (e.g., objective). In the third column, for the specified hazard and for each technical element, the necessary attributes and characteristics are identified. This identification also takes into consideration if the attributes and characteristics differ because of the application and activity.

Table 2-3 Staff Position of an Acceptable Peer Review Items Attributes and Characteristics Peer Review Process Resolution of facts and observations Team Qualifications Documentation 2.2.6 Task 2-6 Identify and resolve technical and policy issues The objective of this task is to identify technical and policy issues that may need to be resolved in order to develop a PRA for an NLWR and determine how these issues are addressed in the NLWR PRA standard. It is important to understand these issues since they could have a significant impact on the ability to develop a PRA model for an NLWR and establish confidence in the results produced by the PRA model.

This effort involves reviewing each technical element associated with all stages of sequences from initiator to consequence, all modes of operation, and all hazards, for the different types of applications, and identifying possible technical or policy issues and their significance. This identification generally occurs while developing the attributes and characteristics.

2.3 Task 3: Staff Review and Endorsement of the NLWR PRA Standard The objective of this task is to review, develop, and document the staff position on the ANSI NLWR PRA standard. This work includes the following subtasks:

  • Subtask 3-1: Develop preliminary trial use regulatory guide (RG)
  • Subtask 3-2: Review NLWR PRA standard for endorsement
  • Subtask 3-3: Issue trial use RG 2.3.1 Task 3-1 Develop preliminary trial use regulatory guide The objective of this task is to develop a preliminary trial use regulatory guide. A trial use RG may be used by applicants in the same way that a final RG is used. Issuance of a trial use RG will allow a longer time period for the staff to gain insights from initial users and receipt of public comments that can be used to improve the RG before it is made into a final RG in the future. This trial use RG, when finalized, will provide the vehicle for staff endorsement. There is a formal template available to develop RGs. However, it is assumed that this new trial use RG will be similar in structure to RG 1.200. This work can begin prior to when the NLWR PRA standard is finalized and issued as an ANSI consensus PRA standard.

This effort involves developing the preliminary trial use RG using the RG template and the results from Task 2. This preliminary trial use RG will provide the staff position in four areas:

(1) A technically acceptable PRA - this section uses the results from Task 2-5 (2) Use of consensus PRA standards and related industry PRA programs - this section uses the results from Task 2-5 (3) Demonstrating the technical acceptability of the PRA to support a regulatory application - this section uses the results from Task 2-1 (4) Documentation needed to support a regulatory submittal.

The scope of each of the above areas is addressed in the trial use RG. This part of the trial use RG provides the staff guidance (position) but not the actual endorsement of the NLWR PRA standard or related industry guidance (peer review).

The product of this effort is a preliminary trial use RG that provides the staff position; it does not include any staff endorsement.

2.3.2 Task 3-2 Review NLWR PRA standard for endorsement The objective of this task is to develop the staff endorsement of the published NLWR consensus PRA standard, which is part of the staff position on PRA acceptability for NLWR PRAs. The activities associated with this task involve a review against the characteristics and attributes for an acceptable PRA (developed in Task 2-4) for each requirement. This review is also performed using the review guidance developed in Task 2-3.

The staffs position on each requirement is to be categorized as no objection, no objection with clarification, or no objection subject to the following qualification, and defined as follows:

  • No objection - The staff has no objection to the requirement.
  • No objection with clarification - The staff has no objection to the requirement.

However, certain requirements, as written, are either unclear or ambiguous, and therefore the staff has provided its understanding of these requirements.

  • No objection subject to the following qualification - The staff has a technical concern with the requirement and has provided a qualification to resolve the concern.

The staff review considers the acceptability of the NLWR PRA standard with respect to the different applications and anticipated activities (as described in Tasks 2-1, 2-4, and 2-5).

As the staff reviews and endorses the NLWR PRA standard against the staff position developed in Task 2-4, additional technical issues needing resolution may arise or the staff may identify a need to revise or provide further clarification of the developed staff position.

These issues need to be identified and documented (as per Task 2-6).

This endorsement will be documented in the trial use RG and will follow the normal process for development of a trial use RG. In the interim, if NRC acceptance of the NLWR PRA standard is needed before the trial use RG can be issued, the NRC may elect to issue an interim letter of acceptance.

The product of this effort involves using the following table (Table 3-1) as a template.

Table 3-1 Staff Position on NLWR PRA Standard Standard Issue Objection Comments Requirement In the first column, each requirement is referenced. If there is an issue with the requirement, the issue is described in the second column. In the third column, the issue is characterized as either a clarification or a qualification. In the fourth column, the proposed language that is needed to address the objection is provided; that is, how the requirement needs to be stated such that there is no objection (i.e., no clarification or no qualification).

2.3.3 Task 3-3 Publish trial use RG The objective of this task is to finalize and issue the trial use RG using the outputs from Tasks 3-1 and 3-2 which provide the staff position on acceptability of PRAs for NLWRs, including endorsement of the NLWR PRA standard and NEI 20-09.

This task includes editing and concurrence, as well as a briefing to the ACRS subcommittee.

The duration of the trial use period for this RG has yet to be established. The staff intends to use the trial use RG to facilitate its reviews of applications and encourages applicants to use it to ensure a timely and more efficient review. The public may provide comments to the NRC while the trial use RG is available.

2.3.4 Task 3-4 Publish Final Regulatory Guide Following the conclusion of the trial use period established in Task 3-3 the staff anticipates issuing a final RG using the following process:

  • Evaluate and resolve public comments and lessons learned from early adoption to revise the RG where appropriate
  • Edit the document and obtain necessary concurrences
  • Hold an ACRS Full Committee briefing
  • Issue final RG for use.

This effort is completely dependent on Tasks 3-1,3-2, and 3-3 and therefore cannot start until those tasks are completed.

2.4 Task 4: Development of schedule for Staff Review and Endorsement The objective of this task is to develop a schedule for Tasks 1 through 3. This schedule will be conditional on the completion of the necessary PRA standards. Key milestones associated with the various tasks and their anticipated completion dates are shown in Table 4-1.

For internal use only February 19, 2021 Table 4-1 Schedule for Completion of Review and Endorsement of NLWR PRA Standard TASK/MILESTONE Responsible Completion Org* Date**

Task 1: Development of NLWR PRA Standard

  • 1-1: Technical issues JCNRM March 2020***
  • 1-2: Readiness review March 2020***
  • 1-3: Consensus ballots September 2020***
  • 1-4: Technical editing (post ballot) December 2020***
  • 1-45 ANSI Public review and comment December 2020***
  • 1-6: Final JCNRM review December 2020***
  • 1-7: ANSI publication February 2021***

Task 2: Preparation for Review of the NLWR PRA Standard and Industry Peer Review Guidance

  • 2-1: Determine scope of regulatory activities NRR/DANU and July 31, 2020***

RES/DRA

  • 2-2: Identify the needed technical expertise to RES/DRA and September review the NLWR PRA standard NRR/DANU 2019***
  • 2-3: Development of staff guidance February 2021
  • 2-4: Comparison of the NLWR PRA February 2021
  • 2-5: Develop staff position for an acceptable March 2021 NLWR PRA and peer review guidance
  • 2-6: Identification and resolution of technical January 2021***

and policy issues Task 3: Staff Review and Endorsement of the NLWR PRA Standard and Industry Peer review guidance

  • 3-1: Develop trial use regulatory guide RES/DRA and June 2021 NRR/DANU
  • 3-2: Review NLWR PRA standard June 2021
  • 3-3: Publish trial use Reg Guide December 2021
  • 3-4: Publish final RG tbd Task 4: Develop schedule for staff review and RES/DRA and January 2020 ***

endorsement NRR/DANU For internal use only February 19, 2021

  • In this column, when two offices are noted, the first noted Office has the lead for that task or subtask.
    • The completion dates for Task 3 is dependent on JCNRM meeting the completion dates for Task 1.
      • These tasks have been completed, these represent the actual dates of completion.

For internal use only February 19, 2021 2.5 Task 5: Development of Communication Plan The objective of this task is to identify how the work will be communicated internally and externally. This communication will include (1) explaining the staff activities to stakeholders, and (2) describing the staffs approach. The plan will provide a structure for communicating the messages to stakeholders.

The various stakeholders include:

  • Internal stakeholders - including technical staff, management, OGC, and ACRS
  • External stakeholders - including the public, ASME/ANS JCNRM, NEI, and potential applicants.

2.5.1 Communication with internal stakeholders The Project Team (consisting of the lead reviewers in NRR and RES, the senior level advisor, and the project manager) will periodically interact with Division management in RES and NRR at key milestones to provide the status of the project. The interactions will address:

  • The progress of the work
  • The schedule and resources
  • Key issues needing resolution.

The staff will brief senior management at the direction of Division management.

The Project Team will hold project meetings with the review team as needed, but no less than one per month. The objective of these meetings is to communicate the status and progress of the overall project and discuss issues needing resolution. The purpose of the meetings is to ensure consistency and traceability of the work.

The staff will consult with OGC to ensure there is no legal objection. OGC advice may be sought to confirm that there is no legal issue when issuing the trial use RG and final RG.

The staff will brief the ACRS as part of the normal process of developing a RG. The staff briefed the ACRS subcommittee in November 2020 to provide early insights into the content of the standard and the staffs plans for endorsement and plans to brief ACRS again before issuance of the trial use RG. A meeting of the ACRS subcommittee will occur before issuance of the trial use RG, and a meeting of the full ACRS will occur before issuance of the final RG. The ACRS may request briefings at other times.

2.5.2 Communication with external stakeholders Staff participate in the ASME/ANS JCNRM, which is responsible for developing the NLWR PRA standard. The staff participation includes representation on the JCNRM and on its For internal use only February 19, 2021 associated Subcommittee on Development and Maintenance2 and the NLWR writing group.

In this manner, the staff is able to communicate its staff position from the outset of the development of the NLWR PRA standard. The staff also provides formal comments as part of the ASME/ANS balloting process. Although the NLWR PRA standard is developed as part of a consensus process, the staff may still need to take exception to fulfill its statutory mission.

As the staff reviews the NLWR PRA standard and NEI 20-09 for endorsement, the staff will hold public meetings to share its views and to solicit input. The following public meetings are proposed:

  • During Task 2, to share staffs initial views on development of the staff position and technical issues
  • During Task 3-2, to share staffs review of the NLWR PRA standard and NEI 20-09
  • During Task 3-3, to discuss the RG, once the trial use RG has been issued
  • During Task 3-3, to address public comments received on the trial use RG.

In addition, advanced reactor stakeholder meetings or separate public meetings will be held at which the staff will share the status of implementation of this plan and early insights into staff observations and perspectives While the trial use RG process does not include a formal public review and comment period, regular public meetings will provide an opportunity for stakeholders to provide comments on the staffs perspectives on PRA acceptability for advanced reactor as it is developing the RG.

3.0 REFERENCES

1. USNRC, Use of Probabilistic Risk Assessment Methods in Nuclear Activities: Final Policy Statement, Federal Register, Vol. 60, p. 42622 (60 FR 42622), August 16, 1995.
2. SECY-15-002, Proposed updates of Licensing Policies, Rules and Guidance for Future New Reactor Applications, U.S. Nuclear Regulatory Commission, Washington, DC, January 8, 2015.
3. 10 CFR Part 50, Domestic licensing of production and utilization facilities.
4. 10 CFR Part 52, Licenses, certifications, and approvals for nuclear power plants.
5. ASME/ANS RA-Sa-2009, Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Applications, Addendum A to RA-S-2008, ASME, New York, NY, American Nuclear Society, La Grange Park, Illinois, February 2009.

2 While the advanced non-LWR PRA standard is being developed (prior to publication as an ANSI standard, it is under the Subcommittee on Development. Once the advanced non-LWR PRA standard is published it comes under the Subcommittee on Maintenance.

For internal use only February 19, 2021

6. ASME/ANS RA-S-1.4-2021, Probabilistic Risk Assessment Standard for Advanced Non-Light Water Reactor Nuclear Power Plants, American Society of Mechanical Engineers and American Nuclear Society, 2021
7. Joint Committee on Nuclear Risk Management (JCNRM) Letter to the NRC Communicating Plan for Advanced Non-LWR Standard Development, November 2020 (ML20031D602).
8. Regulatory Guide 1.200, An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities, U.S. Nuclear Regulatory Commission, Washington, DC.
9. Nuclear Energy Institute (NEI) 18-04, Risk-Informed Performance-Based Guidance for Non-Light Water Reactor Licensing Basis, September 2018. (ADAMS Accession No. ML18271A172)
10. Draft Regulatory Guide 1353, Guidance for a Technology-Inclusive, Risk-Informed, and Performance-Based Methodology to Inform the Licensing Basis and Content of Applications for Licenses, Certifications, and Approvals for Non-Light Water Reactors, April 2019.
11. USNRC, Guidelines for Review and Endorsement of the ASME/ANS PRA Standard for Advanced Non-LWR Nuclear Power Plants and Industry Peer Review Guidance, August 2019 (ML19235A285).
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