ML20212L776

July 22, 2020, Summary of Public Meeting to Discuss the Advanced Non-LWR PRA Standard

ML20212L776
Person / Time
Issue date:	09/21/2020
From:	David Williams NRC/NRR/DANU/UARL
To:	Benjamin Beasley NRC/NRR/DANU/UARL
Williams D,NRR/DANU/UARL,4151322
References
Download: ML20212L776 (9)

Text

September 21, 2020 MEMORANDUM TO: Benjamin Beasley, Chief Advanced Reactor Licensing Branch Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation FROM: Donna Williams, Project Manager /RA/

Advanced Reactor Licensing Branch Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation

SUMMARY

OF JULY 22, 2020, PUBLIC MEETING TO DISCUSS THE ADVANCED NON-LIGHT-WATER REACTOR PROBABILISTIC RISK ASSESSMENT STANDARD On July 22, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20183A073), the U.S. Nuclear Regulatory Commission (NRC) held a Category 2 public meeting with stakeholders, including the Nuclear Energy Institute (NEI), to discuss the staffs review of draft standard, ASME/ANS (American Society of Mechanical Engineers/ American Nuclear Society) RA-S-1.4 and NEI 20-09, Rev. 0, Performance of PRA [Probabilistic Risk Assessment]

Peer Reviews Using the ASME/ANS Advanced Non-LWR PRA Standard. The presentation slides can be found at ADAMS Accession No. ML20203M336. Enclosure 1 lists the meeting attendees.

The purpose of the meeting was to:

• Provide an update on the advanced non-LWR (light-water reactor) PRA standard review and endorsement;

• discuss plans for review and endorsement of NEIs guidance on peer review (NEI-20-09) and discuss observations from initial review of NEI-20-09; and

• discuss the scope of the Regulatory Guide and seek feedback from the public.

Prior to the meeting, the staff had provided the meeting slides to NEI that included a list of preliminary observations that the staff wanted to discuss regarding NEI 20-09. The NEI provided responses to the observations to support the meeting discussions; these responses are included as .

The meeting began with NRC updates on the status of its endorsement of the standard including the planned schedule. The staff then discussed the preliminary observations identified from its initial review of NEI 20-09.

CONTACT: Donna Williams, NRR/DANU 301-415-1322

B. Beasley The NEI stated that they plan to revise NEI 20-09 to address some of the staffs observations and will resend it to the staff in August 2020. Following receipt of the revised document, the staff and NEI will hold another public meeting to discuss the changes and any additional observations that the staff has identified. For the last agenda item, Scope of the Staffs Efforts to Endorse the advanced non-LWR PRA Standard, the staff discussed the applicability of the standard to various licensing applications, related rulemakings that are ongoing and may impact the use of the standard, and observations on the scope of the regulatory guide to be developed.

Enclosures:

1. List of Attendees

2. NEI responses to staff observations on NEI 20-09

ML20212L776 *via Email NRC-001 OFFICE NRR/DANU/UARL/PM* NRR/DANU/UARL/LA* NRR/DANU/UARL/BC* NRR/DANU/UARL/PM*

NAME DWilliams SLent BBeasley DWilliams DATE 7/ 31 /2020 7/31/2020 8/14/2020 9/21/2020 List of Attendees (via Skype or conference call)

Name Organization Michelle Gonzales U.S. Nuclear Regulatory Commission (NRC)

Marty Stutzke NRC Hanh Phan NRC Anders Gilbertson NRC Matthew Humberstone NRC Donna Williams NRC Ismael Garcia NRC Mike Cheok NRC John Nakoski NRC Dale Yielding NRC Alyssa Beasley NRC Tania Martizez Navedo NRC Michelle Hayes NRC Ian Jung NRC Julie Ezell NRC John Lane NRC Derek Widmayer NRC Mehdi Reisi Fard NRC Sunil Weekerody NRC Kati Austgen Nuclear Energy Institute (NEI)

Victoria Andersen NEI Alexandra Renner Oklo Madeline Feltus Department of Energy Mirmiran Sorouche Fennovoima Irina Popova self Jason Redd Southern Nuclear Drew Peebles Kairos Jerry Pemberton self Jana Bergman Scientech Amir Afzali Southern Company Mihai Diaconeasa North Carolina State University Jodine Vehec Holtec Jordan Hagman Kairos Raymond Dremel Enercon Farshid Shahrokhi Framatome Richard Paese self Archie Manoha self Cindy Williams BWXT Nuclear Energy Canada George Flanagan Oakridge National Laboratory Brian Johnson TerraPower Leanne Galanek self Bridget Hawn Kairos Tammy Morin INPO Andrea Maidi self Paul Cochran self Jessica Gee Engineering Planning and Management (EPM), Inc.

Enclosure 1

Preliminary Responses to NRC Comments on NEI 20-09 July 22, 2020, Public Meeting NRC Comment Preliminary Industry Response

1. Non-LWR PRA Life Cycle Stages

a. Are there any differences on the The peer review process is the same; the review process, requirements, way the standard is applied is different.

materials, finding disposition, etc.,

among the peer reviews conducted for the PRAs performed during design stage, COL [Combined License]

stage, construction stage, initial fuel load, and operation?

b. Is NEI 20-09 applicable to the peer Yes, as the same standard is also applicable.

reviews conducted for the mobile reactor PRAs

c. Should there be any differences The PRA Standard and how it is applied are between the peer reviews conducted different. The review process is very similar.

for the existing LWR PRAs (NEI 17-

07) and for the non-LWR PRAs on operating plants (e.g., after the first four-year upgrade)?

d. The non-LWR PRA standard includes No, the PRA is reviewed against the requirements for PRAs performed Capability Category requested by the host before and after initial fuel loading. user.

The capability category assignment for a same PRA may change significantly from one stage to another. Any specific guidance on this aspect?

e. If the PRA being used for a design No, there is not a proxy site. The bounding certification application or risk- site is a hypothetical site based on an informed application does not have a assumed set of external hazard scenarios, specific site, should a review of the meteorological conditions and population.

proxy site information be included? The peer review needs to be performed to confirm the PRA meets the assumptions made in the definition of the bounding site.

f. The discussion in Sections 2.1 and In the PRA Standard the user decides the 6.4 concerning the potential non- scope of the PRA and which SRs to apply to applicability of certain SRs during which parts of the PRA model. Peer review various plant life cycle stages appears should be done in that context and NEI 20-09 to be inconsistent with the discussion is structured as such.

in Section 1.3 of the non-LWR PRA standard, which states: In addition, some PRA requirements that are appropriate for an operating plant or a plant already constructed may not be achievable or appropriate for a PRA on a plant in various design and Enclosure 2

licensing stages The language used in NEI 20-09 appears to potentially give a false impression that users and peer reviewers may arbitrarily set aside certain SRs due to lack of design or operating details, rather than documenting assumptions and proceeding with the analysis as specified in the non-LWR PRA standard.

2. Technical Terms Used in the Guidance Several terms in NEI 20-09, i.e., self- We intend to retain consistency between 17-assessment, independent review, 07 and 20-09 to streamline the industry peer independent assessment, PRA upgrade, etc., review process.

are not defined in the same context as they are described in the SRP and some other staff guidance. The staff recognizes that these terms are used consistently between NEI 20-09 and NEI 17-07, Rev. 2, which is endorsed in DG-1362.

3. Follow-on Peer Review

a. It is not clear whether a follow-on peer Each PRA at each stage of design, review or a full-scope peer review or a construction, or operation that the user elects focused-scope peer review will be to have a peer review done is a different PRA performed for the plant-specific COL and a different peer review.

applicants PRAs that reference a design-specific PRA and COL holders PRAs that are updated to reflect the site-specific design information and/or design changes/departures.

b. Would the follow-on or focused-scope It would depend upon whether or not the PRA peer review be needed/conducted for had substantially changed such that the a PRA on a certified design, which is changes constituted an upgrade. If so, yes. If subject to the restrictions of 10 CFR not, no.

52.63(a)(1) concerning the finality of standard design certification?

4. Radiological Consequence Peer Review

a. Is there any specific guidance on the See PRA standard requirements for radiological consequence reviews in qualifications addition to the sub-bullet on Page 12 (e.g., physical properties of the fuel, negative temperature coefficient of reactivity, inherently safe capacity, computer software/code)?

b. Section 4.4, Attributes of Review This is generically addressed as Experienced Team, additional expertise for in phases of the type of PRA being reviewed.

radiological consequence reviews We can consider adding this specificity, if should be considered, such as: desired.

• meteorological data 2

• exposure assessment (e.g., exposure factors, shielding)

• modeling of radiation effects to human health

• modeling of emergency response measures

• economic impact modeling.

5. Attributes of Review Team

a. Should the following attributes be See PRA standard requirements for peer included? review. Scope of peer review includes

• knowledge/familiar with the non-LWR training of the peer reviewers on the designs, configurations, procedures, reactors safety design approach.

performance data, in which the plants Additionally, the requirements in Section 4 are not yet built/operated. include Familiar with relevant regulatory

• knowledge/familiar with the LMP and guidance which covers LMP, etc.

other risk-informed application(s) for which the PRA is to be used.

b. It is not clear why the experience This is a recognition that some of these novel expectation for the peer review team designs will need to have review teams led lead is reduced from 10+ years (NEI by individuals with knowledge of the design 17-07) to 5+ years (NEI 20-09). who may have less total experience, but will possess sufficient knowledge to lead the review.

c. It is not clear why the last sentence of This phrase does not add anything, as the the first paragraph in Section 4.1 expectations are clear in the preceding "avoiding a perception of a conflict of portion of the sentence.

interest remains important," has been removed from NEI 17-07.

d. It is not clear why the following

• The first is removed in recognition of sentences in Section 4.4 have been the potential to bring in an expert who removed from NEI 17-07: can contribute in one area of the

• Expert in all phases of the type of review but not others.

PRA being reviewed.

• The second is removed in recognition

• A minimal team size for a full-scope that advanced designs may be peer review is five members. simpler and that peer review teams could be smaller in size.

6. Relative Timing of the Reviews It is unclear whether all reviews (including This is outside the scope of a peer review follow-on peer review, focused-scope review, process guidance document.

in-depth review, and newly developed method review) will be performed and completed prior to the submittal of an application.

7. Figure 1-1, Peer Review Process

a. The language in the second box This can be revised should be modified to fit non-LWR PRAs.

3

b. It is not clear what needs to be done There should be an arrow back to the after the last box. beginning, this will be added.

c. It is not clear why the following sub- These subbullets are still there but have bullets under Item 7 in Section 5.2 moved onto a new page.

have been removed from NEI 17-07:

• Sub-bullet d - Examine results of any sensitivity run(s) performed during the review

• Sub-bullet e - Examine the PRA maintenance and upgrade process

• Sub-bullet f - Review newly developed method.

8. Seismic PRA Peer Review

a. The following statement on Page 12, This language will be adjusted Reviewer(s) focusing on the seismic fragility work should have successfully completed the SQUG Walkdown Screening and Seismic Evaluation Training Course or have demonstrated equivalent experience or training in seismic walkdowns, may not be applicable to a PRA performed prior to construction.

b. Should other requirements in EFRI This is covered by the language regarding Seismic PRA Implementation Guide, Experienced in phases of the type of PRA e.g., The peer review team shall being reviewed in Section 4.4 have the combined experience in the areas of systems engineering, seismic hazard, seismic capability engineering, and SPRAs be included?

c. Seismic margin assessment is not This can be removed if desired.

considered for new reactors as listed on Page A-12.

9. Appendix A: Preparation Material Information to be sent by the host user to the

• The first item will be covered by the peer review team should include: review of maintenance and upgrade.

• Procedure(s) used to assess design

• The second item would be covered by changes for PRA impact, including the guidance on as-to-be-built, as-to-documentation that implements the be-operated plants. We can explicitly procedure, add this to the preparation material

• List of design changes up until the list.

peer review but not incorporated into

• The third item is covered by the the models yet, guidance in Section 8 to consider

• List of key sources of uncertainty and uncertainties and assumptions for key assumptions that drive the PRA each SR, and would therefore be in models and results, the self assessment. It would be most

• Etc. useful to state that the self assessment should include evaluation of uncertainty and key assumptions.

4

10. Practical Implementation Aspects

a. Section 3.1 states that To start the NEI could serve this function. We can add PRA peer review process, the host such as NEI to clarify if helpful.

user should request and schedule a peer review through the appropriate responsible organizing entity (e.g.

Owners Group, independent vendor, industry consortium, etc.), For certain non-LWR designs, an appropriate responsible organizing entity may not have been established. Will NEI serve as a clearinghouse in this situation?

b. For PRAs where a site has not been Not at this time; this is beyond the scope of selected (e.g., PRAs in support of DC, the peer review guidance document.

SDA, and ML applications), the non-LWR PRA standard requires the use of bounding sites. These bounding sites will be used to establish appropriate external hazards and the information needed to develop offsite consequence estimates (e.g.,

meteorology and demographic information). Is there any industry effort to define bounding sites for non-LWRs?

11. Other Minor Clarifications

a. If a normal plant walkdown cannot be Other methods may be used, but are not conducted, should other methods strictly necessary in all cases.

(e.g., tabletop walkdowns, computerized simulations) be necessary?

b. There are no CCIII in the non-LWR This reference will be removed.

PRA standard as cited in Section 8.10.

c. Define and add SQUG - Seismic This will be added.

Qualification Users Group to the document.

d. For PRAs on plants performed prior to This can be added.

construction, the terms as-designed, as-to-be-built, and as-to-be operated should be used.

5