ML23136A550

May 18, 2023, Public Meeting Slides Related to NEI Request to Revise XIE3

ML23136A550
Person / Time
Issue date:	05/18/2023
From:	Harris B NRC/NRR/DNRL/NLRP
To:
References
Download: ML23136A550 (1)

Text

NRC Public Meeting May 18, 2023 Generic Aging Lessons Learned - Subsequent License Renewal (GALL-SLR) Report Aging Management Program (AMP) XI.E3:

Inaccessible Power Cables Not Subject to 10 CFR 50.49

Agenda

• Purpose

• Background

• Discussion

• NRC questions and NEIs proposed responses

• Closing remarks

• Action items

• Next steps

Purpose Discuss NEIs proposed revisions to Aging Management (AMP) XI.E3, Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements, in the Generic Aging Lessons Learned -

Subsequent License Renewal (GALL-SLR) Report

• Summarize the NRC concerns with NEIs proposed revisions

• Discuss NEIs proposed responses to address the NRC concerns

• Summarize next steps

Background

• NEI submitted proposed revisions to Aging Management Programs (AMPs) XI.E3, Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements (January 12, 2022)

• Proposed extending the testing frequency of inaccessible medium-voltage cables that have been tested at least twice in the good range from every 6 years to every 10 years

• NEI referenced EPRI Report 3002000557: Guidelines for managing the aging of cables in submerged environments

• Proposed revisions to the GALL-SLR report

• Independent of NEIs request, NRC staff recently completed a review of EPRI Report 3002000557

• Findings are documented in Research Information Letter (RIL) 2021-11, Assessment of EPRIs Tan Delta Approach to Manage Cables in Submerged Environments: Statistical Review of EPRI Data (January 27, 2022: ML22019A005)

• NRC staff recommended not to endorse EPRI Report 3002000557

• NRC staff identified list of concerns with NEIs request

• Includes concerns documented in RIL 2021-11

• List provided to NEI via email on March 23, 2023 (ML23135A159)

Discussion: NRC Questions

1) The NRC staff previously reviewed the justification document (EPRI Report 3002000557) cited in NEIs January 12, 2022, request and documented its findings denying endorsement of the EPRI Report in Research Information Letter (RIL) 2021-11, Assessment of EPRIs Tan Delta Approach to Manage Cables in Submerged Environments: Statistical Review of EPRI Data. In addition to the findings in the RIL, below are items that were identified during the staffs review of your January 12, 2022, request:

a. EPRI Report 3002000557 made nonconservative assumptions that could skew the results of the study (e.g., assumptions included cables that might not have been subjected to water and/or submergence).

b. The test data in EPRI Report 3002000557 was limited to a certain age of cable (i.e., the age of the tested cables was less than what is considered for the license renewal or subsequent license renewal period). The EPRI report did not address the potential increase in degradation as certain in-scope cables age (including those that may be subject to water, submergence, or other adverse localized environments). Specifically, NEIs proposal assumes either a linear or a negative-sloped aging reliability curve. However, the staff believes that the probability of occurrence of failure increases as service age increases, otherwise known as the bathtub phenomena. So, two good data points are not necessarily an accurate prediction of future performance of cables that are aging steadily. Furthermore, as the in-scope cables are inaccessible, visual inspection is not possible to observe additional signs of degradation.

c. The scope of the cables that could be considered in the aging management program is not clearly defined beyond the obvious (i.e.,

medium voltage inaccessible cables operated greater than 2 kilovolts (kV) up to 35kV). For example, further details need to be provided to narrow the scope of the request by manufacturer, insulation type/material, vintage, etc. The NRC staff also needs to further understand which insulation type(s) do not have an operating experience of good cable failures due to significant moisture effects.

d. The request did not include the geographical/geological differences, as well as, programmatic (i.e., dewatering initiatives), and variances in risk (due to site specific/unique operational experience, number and types of applicable cables, etc.) from site to site.

Discussion: NRC Questions (cont.)

e. The specific technical basis for extending the frequency from 6 to 10 years was not clearly explained.

f. The request did not specify a duration between testing for the provision have been tested at least twice in the good range. Its not clear to the staff whether this would be once - 6 years prior to entering the period of extended operation and then once more when entering the period of extended operation. The staff also needs to further understand if the test results need to be tested in the good range twice consecutively or can it be any two tests that were performed and how two data points is sufficient to show a trend for increasing the testing frequency.

g. The request did not explain how the proposed testing frequency appropriately addresses aging management of in scope cables given the significant age of these cables (e.g., how is this testing frequency acceptable for cables that could be 40, 60, or up to 80 years of age).

h. The request did not explain how a licensee should collect, document, and use test data for assess the capability of in scope cables (including consideration for the need to reduce test frequency if anomalies are discovered).

i. The request did not explain how risk insights were used in determining the acceptability of the test frequency extension.

j. The request did not explain how individual licensees should consider risk in determining if the extended test frequency could be applied to specific cables.

Discussion: NRC Questions (cont.)

• Process related items that should be addressed:

a. On December 7, 2022, NEI sent an email with a list of additional documents that could be available for staff review. The staff was mostly aware of these documents, and some were part of the review resulting in the RIL.

b. In a follow-up email dated December 8, 2022, NEI noted that EPRI Report 3002000557 has not been revised and that they werent aware of any plans for EPRI to update this report to address concerns raised in the RIL (which concluded that more actual data is needed to close the confidence level gap that currently exists due to very limited data points).

c. EPRI Report 3002000557 and other documents provided and/or referenced are not freely available. While the GALL/GALL-SLR is guidance document, the staff expects licensees to follow this guidance unless justifiable exceptions are provided. Citing a report that must be purchased to satisfy the GALL/GALL-SLR would apply unnecessary burden on licensees that do not want to purchase documents.

Closing Remarks

• Summary of action items

• Next steps

• Proposed options for NRC completing the review of NEIs request