ML24093A039

Comment (1) of Thomas Basso on Preparing Probabilistic Fracture Mechanics Submittals

ML24093A039
Person / Time
Site:	Nuclear Energy Institute
Issue date:	03/28/2024
From:	Basso T Nuclear Energy Institute
To:	Office of Administration
References
NRC-2024-0036, 89FR14782 00001
Download: ML24093A039 (1)

Text

4/2/24, 8:10 AM blob:https://www.fdms.gov/e5550316-032b-4ae8-a7da-6e7ed3fa37b7

SUNSI Review CompleteAs of: 4/2/24, 8:10 AM Template=ADM-013 Received: March 28, 2024 E-RIDS=ADM-03 PUBLIC SUBMISSION ADD: Bridget Curran, Status: Pending_Post Michael Eudy, Mary NeelyTracking No. lub-oagu-hlts

Comment (1) Comments Due: April 01, 2024 Publication Date: 2/29/2024Submission Type: Web Citation: 89-FR-14782 Docket: NRC-2024-0036 Preparing Probabilistic Fracture Mechanics Submittals

Comment On: NRC-2024-0036-0001 Draft Regulatory Guide: Preparing Probabilistic Fracture Mechanics Submittals

Document: NRC-2024-0036-DRAFT-0002 Comment on FR Doc # 2024-04222

Submitter Information

Organization: Nuclear Energy Institute

General Comment

See attached file(s)

Attachments

03-28-24_NRC_Industry Comment DG 1422

blob:https://www.fdms.gov/e5550316-032b-4ae8-a7da-6e7ed3fa37b7 1/1 Thomas Basso Phone: 202.739.8049 Sr. Director, Engineering & Risk Email: tbb@nei.org

March 28, 2024

Office of Administration U.S. Nuclear Regulatory Commission, Washington, DC 20555- 0001 Attn: Program Management, Announcements and Editing Staff

Subject:

Comments of the Nuclear Energy Institute on Draft Regulatory Guide, Preparing Probabilistic Fracture Mechanics Submittals, 89 Fed. Reg. 14782 (February 29, 2024) (Docket ID: NRC-2024- 0036)

Dear Program Management,

Announcements and Editing Staff:

The Nuclear Energy Institute (NEI) 1 is pleased to provide the following comments on the draft regulatory guide referenced above (DG-1422), which would provide new guidance on preparing submittals that use probabilistic fracture mechanics (PFM) analyses in support of regulatory actions. If finalized, DG-1422 would provide this new guidance through a revision to an existing regulatory guide - Regulatory Guide 1.245, Preparing Probabilistic Fracture Mechanics Submittals (RG 1.245).

Specifically, DG-1422 would revise Regulatory Position C.2 in RG 1.245 to communicate a new position requiring applicants using PFM to apply the guidance in Regulatory Guide 1.174, An Approach for Using Probabilistic Risk Assessment in Risk -Informed Decisions on Plant-Specific Changes to the Licensing Basis (RG 1.174), including implementation of performance monitoring strategies. NEI disagrees with the new regulatory position communicated in DG-1422 - both on its merits and because, if finalized, DG -1422 would meet the definition of forward fitting and was not properly evaluated under the agencys guidance in Management Directive 8.4. 2

1 The Nuclear Energy Institute (NEI) is responsible for establishing unified policy on behalf of its members relating to matter s affecting the nuclear energy industry, including the regulatory aspects of generic operational and technical issues. NEIs members include entities licensed to operate commercial nuclear power plants in the United States, nuclear plant designers, major arc hitect and engineering firms, fuel cycle facilities, nuclear materials licensees, and other organizations involved in the nuclear energy industry.

2 Management Directive 8.4, Management of Backfitting, Forward Fitting, Issue Finality, and information Requests, Sept. 20, 2019 (MD 8.4).

Program Management, Announcements and Editing Staff Nuclear Energy Institute March 28, 2024 Page 2

PFM Methodologies are not Risk-Informed Methodologies

As communicated in our April 27, 2023, presentation, NEI disagrees with the position that the guidance in RG 1.174 applies to applications using PFM in situations where the application does not make use of the licensees probabilistic risk assessment (PRA). 3

DG-1422 would require that any regulatory application that uses PFM in support of a technical basis be submitted as a risk-informed application to satisfy the RG 1.174 integrated decision-making principles. The purpose of PFM is to model the behavior and degradation of systems more accurately than traditional deterministic fracture mechanics, and consequentially draw more precise and accurate conclusions about situations relative to performance criteria or design assumptions.

Simply because a probability is computed does not make PFM a risk-informed application. DG-1422 is inconsistent with the NRCs own definition of a risk-informed approach: 4

A risk-informed approach to regulatory decision-making represents a philosophy whereby risk insights are considered together with other factors to establish requirements that better focus licensee and regulatory attention on design and operational issues commensurate with their importance to health and safety.

In DG-1422, it seems as though the staff has conflated the computation of a probability with risk.

DG-1422 says that PFM provides risk insights and therefore there is a need for an integrated decision-making process like RG 1.174. Yet, the NRCs definition of risk insights 5 is "The understanding about a facilitys response to postulated accidents. PFM only provides an assessment of the likelihood of a failure of a component and does not address the facility response. Therefore, the application of the RG 1.174 integrated decision-making is inappropriate. NEIs position is consistent with both the relevant EPRI technical guidance 6 and the language of RG 1.174 itself, which cites these definitions. Industry acknowledges that PFM may be used with or in support of risk-informed decision-making for licensing basis changes. In those cases where risk insights are used, application of R G 1.174 principles make sense. However, when PFM methods alone are used, and the response of all plant structures, systems and components are not evaluated to calculate core damage frequency or large early release frequency, RG 1.174 should not be used. To that end, the approved guidance in RG 1.245 Rev. 0 makes no reference to either consequences or performance monitoring.

3 NEI, NEI Perspective on Performance Monitoring in Use of Probabilistic Fracture Mechanics for Optimizing Inspections of Non-RPV Pressure Vessels, April 27, 2023.

4 NRC, NUREG-2122, Glossary of Risk -Related Terms in Support of Risk -Informed Decisionmaking, Washington, DC, November 2013.

5 Ibid.

6 N. Palm (EPRI), BWR Vessel & Internals Project (BWRVIP) Memo No. 2019016, "White Paper on Suggested Content for PFM Submittals to the NRC," February 27, 2019 (ADAMS Accession No. ML19241A545).

Program Management, Announcements and Editing Staff Nuclear Energy Institute March 28, 2024 Page 3

The New Regulatory Positions Contained in DG-1422 Must be Evaluated as Forward Fitting

The NRC defines forward fitting as:

[T]he imposition of a new or modified requirement or regulatory staff interpretation of a requirement that results in the modification of or addition to systems, structures, components, or design of a facility; or the design approval or manufacturing license for a facility; or the procedures or organization required to design, construct or operate a facility as a condition of approval by the NRC of a licensee-initiated request for a licensing action when the underlying request did not propose to comply with the new or revised requirement or interpretation.7

The Regulatory Position C.2 communicated in DG-1422 is a new or modified interpretation of what is required to credit PFM in support of regulatory applications, including applications for use of alternatives to codes and standards requirements. Specifically, as stated in the regulatory analysis accompanying DG-1422, the current revision of RG 1.245 does not include guidance on how risk-informed decision-making principles should be applied to regulatory applications that use PFM as part of their technical basis. 8 To remedy this situation, DG-1422 communicates a new position that RG 1.174 is also applicable to regulatory applications that use PFM as part of their technical basis. 9 This position is not contained in revision 0 of RG 1.245, which simply contains the vague direction that [a]pplicants should be aware that the use of PFM in a regulatory submission is only one aspect of what is required for risk-informed decision making. 10

Indeed, the NRC has unconditionally approved four (4) plant submittals using PFM to support alternatives to codes and standards. The technical basis for these four applications was an EPRI white paper, White Paper on Suggested Content for PFM Submittals to the NRC. 11 The NRC did not require application of RG 1.174 as a condition of approval of these applications. Specifically, the NRC did not require performance monitoring as a condition of those approvals, which is a principle made applicable to risk-informed decisions using P R A under RG 1.174. Imposing the need for performance monitoring, or other elements necessary pursuant to RG 1.174, in all applications supported by PFM would significantly expand the applicability of RG 1.174 and require licensees to modify their engineering evaluation and regulatory submittal processes as a condition of approval of licensee-initiated requests for use of alternatives to codes and standards.

7 MD 8.4, at Handbook pg. 6.

8 NRC, Regulatory Analysis: Draft Regulatory Guide DG -1422 Preparing Probabilistic Fracture Mechanics Submittals, at pg. 1.

9 Id. In describing the alternative to revise RG 1.245, the associated Regulatory Analysis also states this revision would explain that PFM analyses are only one part of a risk -informed regulatory application, and that RG 1.174... is also applicable to regulatory applications that use PFM as part of their technical basis. Id. at pg. 2.

10 Regulatory Guide 1.245, Rev. 0, Preparing Probabilistic Fracture Mechanics Submittals, January 2022, at pg. 10.

11 N. Palm (EPRI), BWR Vessel & Internals Project (BWRVIP) Memo No. 2019016, "White Paper on Suggested Content for PFM Submittals to the NRC," February 27, 2019 (ADAMS Accession No. ML19241A545).

Program Management, Announcements and Editing Staff Nuclear Energy Institute March 28, 2024 Page 4

Thus, if the NRC is proposing to require the use of the guidance contained in DG-142 2 in lieu of the existing guidance provided in revision 0 to RG 1.245, then the changes in DG-142 2 must be properly evaluated as forward fitting prior to the DG -142 2 being finalized. 12

Specifically, MD 8.4 states that:

The NRC may condition its approval of... a licensing action on the use of a new or modified regulatory staff position only if: (1) there is a direct nexus to the licensees request, and (2) the imposition of the new or modified requirement or regulatory staff position is essential to the NRC staffs determination of the acceptability of the licensees request. Staff must address these two elements in its analysis and adequately justify why each one is independently met.13

There is no indication in either DG -142 2, the associated Regulatory Analysis, or the associated Federal Register notice that the staff has addressed these required elements of forward fitting. 14 In addition, MD 8.4 also points out that the Administrative Procedure Act requires some consideration of costs when a forward fit is unrelated to adequate protection. 15 We do not believe, and there is no indication in DG -142 2 or any of the supporting documents, that the forward fit imposed by DG-1422 is necessary to either ensure or redefine adequate protection. This conclusion is affirmed by the fact that, to our knowledge, the NRC has not required backfitting of the four approved pilot plants to impose a performance monitoring requirement (or any other principle provided in RG 1.174).16

While the Regulatory Analysis accompanying DG-142 2 acknowledges that there will be costs associated with preparing and issuing the proposed revision to RG 1.245, it contains no meaningful discussion of those costs and does not attempt to quantify them. 17 Also absent from the Regulatory Analysis is any discussion of costs imposed on applicants because of the revisions contained in DG-1422. Instead, the Regulatory Analysis asserts that applicant acquiescence to new position articulated in DG-142 2 would

12 In the alternative, the NRC should make it clear that applicants desiring to utilize PFM to support regulatory applications m ay do so using either the guidance provided in revision 0 to RG 1.245 or the guidance provided in DG -142 2.

13 MD 8.4, at Handbook pg. 6.

14 The Implementation section of DG -142 2 contains the following conclusory statement : The staff does not intend to use the guidance to support NRC staff actions in a manner that constitutes forward fitting as that term is defined and described in Management Directive 8.4. DG-142 2, at pg. 26. But this boilerplate language is clearly inconsistent with the new regulatory position that is explicitly communicated in both DG -142 2 and the associated regulatory analysis. If the NRC does not intend to require use of the new guidance provided in DG -14 22 in lieu of the existing guidance provided in revision 0 to RG 1.24 5, then that should have been clearly stated in DG-14 22.

15 Id. at pg. 6-7.

16 See MD 8.4, which explains Under the mandatory backfitting provisions of 10 CFR 50.109(a)(5)... regarding backfitting necessary to assure adequate protection of public health and safety, if such a change were necessary to ensure adequate protection of public health and safety when the new or modified requirement or regulatory staff position was made, the NRC would have been required to impose it as a backfit. Because such a backfit has not been imposed for cases where a forward fit is being considered, it is unlikely that a change could be justified to be necessary to ensure adequate protection of public health an d safety. Id. at pg. 7.

17 NRC, Regulatory Analysis: Draft Regulatory Guide DG -1422 Preparing Probabilistic Fracture Mechanics Submittals, at pg. 2.

Program Management, Announcements and Editing Staff Nuclear Energy Institute March 28, 2024 Page 5

actually reduce costs because such acquiescence would reduce the number of requests for additional information and shorten review times, resulting in ongoing cost savings to the NRC and industry.18 This reasoning completely ignores the requirement to consider the costs that flow from imposition of a proposed forward fit and, instead, turns the NRCs forward fitting policy on its head by considering licensee conformance with an unanalyzed forward fit as a benefit (i.e., resulting in cost reduction).

NEI requests that the NRC either withdraw DG-1422, or revise and republish the draft guide for public comment with an adequate forward fit evaluation. The revised draft guide should limit the application of RG 1.174 principles to those submittals that use PFM in support of a risk-informed application since not all applications that may use PFM to support a technical basis are risk-informed.

Sincerely,

Thomas Basso Sr. Director, Engineering & Risk

CC: John Tappert, Acting Director, RES, NRC Marissa Bailey, RES, NRC Michael A. Eudy, RES, NRC Patrick Raynaud, RES, NRC

18 Id.