ML23087A095

GEH BWRX-300 March 8, 2023, Public Meeting Summary LTR NEDC-33934P, Safety Strategy

ML23087A095
Person / Time
Site:	99900003
Issue date:	04/06/2023
From:	James Shea NRC/NRR/DNRL/NLIB
To:	Hayes M NRC/NRR/DNRL/NLIB
References
Download: ML23087A095 (12)

Text

April 6, 2023 MEMORANDUM TO:

Michelle W. Hayes, Chief Licensing and Regulatory Infrastructure Branch Division of New and Renewed Licenses Office of Nuclear Reactor Regulation FROM:

James J. Shea, Project Manager /RA/

Licensing and Regulatory Infrastructure Branch Division of New and Renewed Licenses Office of Nuclear Reactor Regulation

SUMMARY

OF PUBLIC MEETING TO DISCUSS PRE-APPLICATION LICENSING TOPICAL REPORT ON SAFETY STRATEGY FOR THE BWRX300 SMALL MODULAR REACTOR On March 8, as continued on April 5, 2023, an Observation Public Meeting was held between the U.S. Nuclear Regulatory Commission (NRC) staff and GE-Hitachi Nuclear Energy Americas, LLC (GEH) concerning the expected submittal of the license topical report (LTR) on BWRX300, Safety Strategy.

These two meetings were a continuation of discussions on the GEH proposed Safety Strategy for the BWRX300 starting in June 2022. GEH provided a presentation of additional detail on the expected content of its BWRX300 Safety Strategy that included only publicly available information.

The topics discussed during this meeting included the following:

Purpose of the Safety Strategy LTR.

Technical detail on the GEH Safety Strategy approach including graded approach to structures systems and component (SSC) classification, exemptions to NRC regulations, alternatives to NRC general design criteria and NRC Regulatory Guidance.

Proprietary discussion of specific aspects of the Safety Strategy that is the basis for design and safety classifications of specific BWRX300 SSCs.

CONTACT: James Shea, NRR/DNRL 301-415-1366

M. Hayes 2

The NRC issued the public meeting notice on January 30, 2023, (Agencywide Documents Access Management System (ADAMS) Accession No. ML23030B916) and on March 16, 2023, (ML23075A322) and posted it on the NRC public website. Prior to the meeting(s), GEH submitted presentation slides on February 28, 2023 (ML23059A453).

Enclosed are the meeting agenda (Enclosure 1), list of participants of the meeting (Enclosure 2), and summary of the meeting with some staff feedback on the GEH presentation and BWRX300 Safety Strategy approach (Enclosure 4).

Docket No. 99900003

Enclosures:

1. Meeting Agenda

2. List of Attendees

3. Meeting Summary and Staff Feedback on the BWRX300 Safety Strategy Approach

Pkg: ML23087A077 Memo: ML23087A095 Slides: ML23059A453

• via email NRR106 OFFICE NRR/DNRL/NRLB: PM NRR/DNRL/NRLB: LA NRR/DNRL/NRLB: BC NAME JShea*

SGreen*

MHayes*

DATE 04/06/2023 05/18/2023 05/22/2023

U.S. NUCLEAR REGULATORY COMMISSION

SUMMARY

OF THE MARCH 8, 2023, OBSERVATION PUBLIC MEETING TO DISCUSS PRE-APPLICATION LICENSING TOPICAL REPORT ON SAFETY STRATEGY FOR THE BWRX300 SMALL MODULAR REACTOR Meeting Agenda March 8, 2023 Time Topic Speaker 10:00 am - 12:45 pm GEH Public Presentation of LTR Technical Topics GEH 12:45 pm - 1:00 pm Public Questions and Final Staff Feedback and Observations GEH/NRC Meeting Agenda April 5, 2023 Time Topic Speaker 8:00 am - 10:45 am GEH Public Presentation of LTR Technical Topics GEH 10:45 am - 11:00 am Public Questions and Final Staff Feedback and Observations GEH/NRC 11:00 am - 12:30 pm Proprietary Discussion and Staff Questions and Observations GEH/NRC

U.S. NUCLEAR REGULATORY COMMISSION

SUMMARY

OF THE MARCH 8 AND APRIL 5, 2023, OBSERVATION PUBLIC MEETING TO DISCUSS PRE-APPLICATION LICENSING TOPICAL REPORT ON SAFETY STRATEGY FOR THE BWRX300 SMALL MODULAR REACTOR List of Attendees March 8, 2023 Name Organization Name Organization Jim Shea NRC Matthew Gordon NRC Jordan Glisan NRC Dan Beacon NRC Michelle Hayes NRC Sunnil Weerakkody NRC Brian Smith NRC David Nold NRC Stacey Rosenberg NRC Joseph Ashcraft NRC Mike Franovich NRC Calvin Cheung NRC Joseph Donoghue NRC Dinesh Taneja NRC Stewart Bailey NRC Bedi Gurjendra NRC Elijah Dickson NRC Biro Mihaela NRC Anne-Marie Grady NRC Chris Van Wert NRC Marie Pohida NRC John Segala NRC Phan Hanh NRC Norbert Carte NRC Angelo Stubbs NRC Edward Robinson NRC Brian Wittick NRC Shilp Vasavada NRC Ryan Nolan NRC Getachew Tesfaye NRC Meena Khanna NRC Yuken Wong NRC Getachew Tesfaye NRC Mihaela Brio NRC Shanlai Lu NRC George Wadkins GEH Kaihwa Hsu NRC David Hinds GEH Steve Jones NRC Jesus Diaz-Quiroz GEH Todd Smith NRC Lou Lanese GEH Alvarado Rossnyev NRC Mark Burzynski GEH Antonio Barrett NRC Thomas Walker GEH Kamal Manoly NRC Frostie White GEH Yuken Wong NRC Scott Zinkham GEH Ian Jung NRC Bernard Gilligan GEH Sawant Pravin NRC Paul Infanger GEH Nicholas Hansing NRC James Curry GEH

2 Name Organization Name Organization Kyle Song NRC Jun Matsumoto GEH Bruce Bennett GEH Ray Schiele TVA Thomas Demitrack GEH Steven Hilmes TVA Elena Sorin GEH Kevin Casey TVA Hisatoshi Shirahama GEH David Daigle TVA Phillip Henderson GEH Michele Moorrees TVA James Thornton TVA Stephen Kimura TVA John Sullivan TVA Scott Owen TVA John Philip TVA Dennis Petrarca TVA Tony Jackson TVA Veronica Kyles TVA Joel Klein TVA Brian McDermott TVA Kelvin Montague TVA William Ryan TVA Aurelian Tanase CNSC Douglass Miller CNSC Yong Chang Liu CNSC Morin Chantal CNSC Mounia Berdai CNSC Steven Pope ISL Ryan Henderson Southern Company Jana Bergman Curtis Wright Leigh Lloveras Adam Stein Charlyne Smith Break Through Institute

3 List of Attendees April 5, 2023 Name Organization Name Organization Jim Shea NRC Matthew Gordon NRC Jordan Glisan NRC Dan Beacon NRC Michelle Hayes NRC Sunnil Weerakkody NRC Brian Smith NRC David Nold NRC Stacey Rosenberg NRC Joseph Ashcraft NRC Mike Franovich NRC Calvin Cheung NRC Joseph Donoghue NRC Dinesh Taneja NRC Stewart Bailey NRC Bedi Gurjendra NRC Elijah Dickson NRC Biro Mihaela NRC Anne-Marie Grady NRC Chris Van Wert NRC Marie Pohida NRC John Segala NRC Phan Hanh NRC Norbert Carte NRC Angelo Stubbs NRC Edward Robinson NRC Brian Wittick NRC Shilp Vasavada NRC Ryan Nolan NRC Getachew Tesfaye NRC Meena Khanna NRC Yuken Wong NRC Getachew Tesfaye NRC Mihaela Brio NRC Shanlai Lu NRC George Wadkins GEH Kaihwa Hsu NRC David Hinds GEH Steve Jones NRC Jesus Diaz-Quiroz GEH Todd Smith NRC Lou Lanese GEH Alvarado Rossnyev NRC Mark Burzynski GEH Antonio Barrett NRC Thomas Walker GEH Kamal Manoly NRC Frostie White GEH Yuken Wong NRC Scott Zinkham GEH Ian Jung NRC Bernard Gilligan GEH Sawant Pravin NRC Paul Infanger GEH Nicholas Hansing NRC James Curry GEH

4 Name Organization Name Organization Kyle Song NRC Jun Matsumoto GEH Bruce Bennett GEH Ray Schiele TVA Thomas Demitrack GEH Steven Hilmes TVA Elena Sorin GEH Kevin Casey TVA Hisatoshi Shirahama GEH David Daigle TVA Phillip Henderson GEH Michele Moorrees TVA James Thornton TVA Stephen Kimura TVA John Sullivan TVA Scott Owen TVA John Philip TVA Dennis Petrarca TVA Tony Jackson TVA Veronica Kyles TVA Joel Klein TVA Brian McDermott TVA Kelvin Montague TVA William Ryan TVA Aurelian Tanase CNSC Douglass Miller CNSC Yong Chang Liu CNSC Morin Chantal CNSC Mounia Berdai CNSC Steven Pope ISL Ryan Henderson Southern Company Jana Bergman Curtis Wright Leigh Lloveras Adam Stein Charlyne Smith Break Through Institute

NUCLEAR REGULATORY COMMISSION

SUMMARY

OF THE MARCH 8, AND APRIL 5, 2023, PUBLIC OBSERVATION MEETING REGARDING LICENSING TOPICAL REPORT ON SAFETY STRATEGY FOR THE BWRX300 SMALL MODULAR REACTOR Meeting Summary and Staff Feedback The meetings were held from 10.00 am-1:00 pm on March 8, 2023, and from 8:00 am-12:30 pm on April 5, 2023. The NRC staffs opening remarks described the previous engagements with GEH on a proposed licensing topical report (LTR) regarding a Safety Strategy for the BWRX-300 small modular reactor. This included a June 29, 2022, public meeting (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22215A081), an August 5, 2022, non-public Page Turn meeting with subsequent feedback (ML22263A294), a white paper, BWRX300 Safety Strategy that GEH submitted on December 7, 2022 (ML22341A058) and a December 14, 2022, public meeting (ML23023A142) where NRC feedback on the white paper was discussed.

The NRC introduced the Canadian Nuclear Safety Commission (CNSC) review team participating in this meeting as part of a 2019 memorandum of cooperation between the NRC and CNSC, and a September 2022, Charter - Collaboration on GEHs BWRX300 Design.

GEH provided its presentation on February 28, 2023 (ML23059A453) to the NRC and CNSC staff. The meeting on March 8, 2023, ended before GEH could complete its presentation so it continued on April 5, 2023, during the public session. The staff held a closed portion of the meeting on April 5, 2023, to allow discussions on specific proprietary design attributes of structures, systems, and components (SSCs).

BWRX300 Safety Strategy Design Process Philosophy and Licensing Framework GEH presented the design process, philosophy, and licensing framework for the BWRX300 Safety Strategy which included a description of the defense line architecture based on selected guidance from the International Atomic Energy Agency Safety Standards Specific Safety Requirements No. SSR2/1, Revision 1, Safety of Nuclear Power Plants: Design, and how it is used to determine the safety category of SSCs. The GEH approach presented in this meeting was described as an alternate licensing framework that would require exemptions to NRC regulations, alternatives to the NRC 10 CFR Part 50, Appendix A, General Design Criteria (GDCs), and deviations to NRC regulatory guidance including NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants, (SRP).

CNSC staff assessment of GEHs proposed Safety Strategy (as described in the white paper and further informed in this meeting presentation) was that it appeared to be generally consistent with CNSCs regulations and processes, except that additional information is needed on certain aspects of safety and the identification of active systems important to safety; and that they would provide additional detailed information on specific safety feature requirements in a formal written feedback assessment.

Issues raised by the NRC staff from information presented in the meetings:

1. The LTR should clearly describe the requested scope of the NRCs review, including the specific findings GEH is seeking.

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2. Because exemptions are design-specific, they cannot be submitted and approved in a pre-application LTR. However, some of the basis and criteria for potential future exemptions could be evaluated in the LTR. To make the review more efficient, the LTR should include the following for each area where the proposed Safety Strategy does not comply with a regulatory requirement:

The scope and summary of the requested exemption, including identification of the specific portion(s) of the regulation from which the exemption is requested.

A technical justification for the request; and An evaluation against the exemption criteria in Section 50.12.

GEH stated that the exemptions included in the presentation may not be the full list as the analysis was ongoing. To ensure staffs complete understanding of this approach, the LTR should include the entire list of exemptions related to the Safety Strategy.

3. Per the BWRX300 Safety Strategy, Anticipated Operating Occurrences (AOOs) are considered Defense Level 2 (DL2) events and are mitigated with safety Category 3 (SC3) SSCs. SC3 SSCs are described as non-safety-related SSCs with reliability targets and special treatment. Because components relied on during or following a design-basis event (DBE) (such as an AOO) to shut down the reactor are defined as safety-related per 10 CFR 50.2, GEH stated that it will request an exemption from this definition. The topical report should also include in the list of exemptions the specific regulations that rely on this definition of safety-related.

4. For AOOs, the GDCs prescribe a safe shutdown condition to be one where decay heat is being sufficiently removed and the fuel integrity barrier is maintained by demonstration of appropriate margin to the specified acceptable fuel design limits (SAFDLs). In the Safety Strategy, the AOO, upon failure of non-safety-related DL2 systems, will be mitigated by safety-related Defense Line 3(DL3) systems. GEH stated that failures of DL2 systems are considered complicated events and are evaluated to DBA acceptance criteria (the term used in the slides) instead of the SAFDLs prescribed by the GDC. The topical report should provide more information on the evaluation criteria used for complicated events.

5. The presentation states that the GEH Economic Simplified Boiling Water Reactor (ESBWR) credited non-safety SSCs to mitigate some of the AOOs. The staff notes that there was no generic approval for ESBWR to credit non-safety-related DL2 systems; the specific approval was highly case-specific and dependent on results of the full transient analysis. The LTR should identify the specific AOOs that need to credit non-safety AOOs to meet SAFDLs.

6. GEHs position is that adding a level of defense (e.g., having both DL2 and DL3) is an overall safety improvement over having a single, safety-related system that protects against all events. The staff notes that non-safety systems also existed in previous GEH designs (such as the advanced boiling-water reactor (ABWR) and ESBWR), but they were not credited in this manner.

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7. The GDCs establish minimum requirements for the principal design criteria (PDC) for water-cooled nuclear power plants similar in design and location to plants for which construction permits (CPs) have been issued by the Commission. BWRX300 is a light-water reactor (LWR) with several design features that are similar to those of a previously approved LWR designs, such as ESBWR, and the ABWR that met the GDCs. It is not clear to the staff that all of the exemptions to the GDCs, and replacement principal design criteria (PDCs), are necessary to implement the proposed Safety Strategy.

8. GEHs presentation demonstrates that probabilistic risk assessment (PRA) information is an integral part of the Safety Strategy, including determination of licensing basis event classification and consequently SSC categorization. Detailed information about PRA acceptability and the use of PRA information in the Safety Strategy methodology is necessary for the staff to evaluate the methodology.

9. Detailed information is necessary on the approach to identify and address key assumptions and sources of uncertainties in the PRA parameters and modeling in the context of the Safety Strategy and Commission Policy on the use of PRA and risk-informed decision making. An example is addressing parametric and modeling assumptions and uncertainties in event classification based on sequence frequency instead of initiating event frequency. NUREG-1855, Revision 1, provides guidance on the treatment of uncertainties associated with PRAs in Risk-Informed Decision making.

The licensing modernization project (LMP) framework in Nuclear Energy Institute 18-04 as endorsed by Regulatory Guide (RG) 1.232 provides an example of how parametric and modeling uncertainty of the fault sequence frequency can be addressed.

10. GEH stated that one of the criteria for demonstrating that the intent of Regulatory Treatment of Non-Safety Systems (RTNSS) is met by the Safety Strategy methodology will be based on risk significance thresholds identified for the BWRX300 design. In response to NRC staffs question, GEH indicated that risk significance thresholds will be part of a separate topical report. Lack of information on the risk significance thresholds and their justification as part of the Safety Strategy review will limit the NRC staffs ability to making any findings on whether the intent of RTNSS is being met.

11. The basis for the 1E05 per reactor-year demarcation between design-basis accidents (DBAs) and design extension conditions (DL 3 and 4a, respectively) needs technical justification that focuses on the BWRX300 design and NRCs regulatory framework.

Certain DBAs prescribed in 10 CFR Part 50 cannot be screened out based on PRA frequencies. For example, an applicant is required to demonstrate compliance with 10 CFR 50.46, Acceptance criteria for emergency core cooling system for light-water nuclear power reactors, and design an emergency core cooling system (ECCS) that can mitigate a hypothetical loss of coolant from the reactor cooling system (RCS). Excluding consideration of losses of coolant from certain locations in the RCS in a mechanistic manner based on component configuration or likelihood of failure will require a technically justified exemption to 10 CFR 50.46 and demonstration of special circumstances in accordance with 10 CFR 50.12. The LTR should identify exemptions from any regulations that will be impacted by this demarcation.

12. In RG 1.76, Revision 1, the design-basis tornado is based on an annual exceedance frequency of 1E-7/y. In RG 1.221, design-basis hurricane and hurricane missiles are based on windspeeds which correspond to the annual exceedance frequency of 1E7/y.

The LTR should describe how external hazards are evaluated in this framework.

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13. The acceptance criteria for the DBA radiological consequences analyses are unclear and does not appear to be graded based on likelihood. The dose acceptance criteria prescribed in the regulations, such as 10 CFR Part 100 and 10 CFR 50.34, of 25 rem total effective dose equivalent are for a hypothesized major accident resulting in fuel melt and is not intended for other DBAs. For instance, SRP Section 15.0.3 and 1.183 identify acceptance criteria as a fraction of this regulatory limit based on the likelihood of the postulated accident. Likewise, while not being utilized for the Safety Strategy, the LMP uses a frequency-consequence curve and provides another example of how a framework can establish graded acceptance criteria. The LTR should specifically describe what acceptance criteria will be used for DBEs.

14. The approach for technical specifications as described in the presentation does not appear to comply with 10 CFR 50.36. Specifically, the GEH approach only considers DL3 SSCs subject to 10 CFR 50.36(c)(2)(ii) Criterion 2 and Criterion 3. However, Criterion 2 and Criterion 3 are for conditions of DBAs and transients, and therefore, apply equally to both DL3 and DL2 events. The LTR should describe how this regulation is met or identify there will be an exemption.

15. Due to the first-of-a-kind nature of the proposed exemptions, the NRC staff may determine this approach contains policy issues that require Commission awareness or direction. Addressing such policy issues may increase review time for the LTR or the CP application.

16. Slide 67 of the presentation identifies transient and accident analysis methodologies that were reviewed and approved for use in the ESBWR Design Control Document. The staff notes that GEH will need to justify the use of these codes for the BWRX300 by considering the differences in the designs, strategies for mitigation of transients/accidents, and the attendant phenomena that are important to each analyzed event sequence.