ML24044A177

RAI for 180 Days Steam Generator Report

ML24044A177
Person / Time
Site:	Beaver Valley
Issue date:	02/14/2024
From:	V Sreenivas Plant Licensing Branch 1
To:	Energy Harbor Nuclear Corp
Goetz S
References
Download: ML24044A177 (1)

Text

1 REQUEST FOR ADDITIONAL INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION BEAVER VALLEY, UNIT 2-180 DAYS STEAM GENERATOR REPORT ENERGY HARBOR NUCLEAR GENERATI BEAVER VALLEY, UNIT 2 DOCKET NO. 05000412 ISSUE DATE: 02/14/2024

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Background===

By letter dated October 31, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23305A095), Energy Harbor Nuclear Corp. (the licensee) submitted the spring 2023 Reports for Beaver Valley Power Station, Unit 2. The steam generator tube inspections were performed during refueling outage 23 (2R23).

Regulatory Basis Technical Specification (TS) Sections 5.6.6.2 requires that a report be submitted within 180 days after the initial entry into hot shutdown (MODE 4) following completion of an inspection of the SGs performed in accordance with TS Section 5.5.5.2, which requires that a SG Program be established and implemented to ensure SG tube integrity is maintained. To complete its review of the inspection, the U.S. Nuclear Regulatory Commission (NRC) staff requests the following additional information.

Question 1

1. During RFO 22 (2R22), four tubes with +Point probe circumferential indications in the Alloy 800 nickel banded sleeve region were plugged. Information about these 2R22 indications (ML23304A213) was subsequently provided to the NRC in response to a request for additional information. Since that time additional investigation was performed, (e.g., mock-up samples fabrication and destructive analysis, eddy current analysis of sleeved tubes and mock-up samples,) to determine the cause of these indications. The investigations showed that the nickel band hardness is higher than the parent tube in the post hard roll condition and can make an impression or indentation in the parent tube, especially at the edge of the nickel. This resulted in the classification of benign indications in more than 40 sleeved tubes that either were in service and were inspected during 2R23 or were initially placed into service during 2R23.

Provide more details about the sleeve mockup testing results including the nickel plating hardness relative to the parent tube hardness and degree of impression into the parent tube. Has the nickel plating composition, material properties, and sleeve plating process remained consistent over the sleeve population placed into service in the Beaver Valley Unit 2 SGs?

2 Describe how circumferential cracking at this location, should it occur, would be differentiated from benign sleeve signal circumferential anomalies attributed to the sleeve installation process. How would benign sleeve indications be expected to change over time compared to a circumferential SCC indication? How are the results of the recent investigations being incorporated into guidance for eddy current data analysts?

Question 2 The comparison of 2R23 condition monitoring results to the previous inspection operational assessment projection is shown in a table (page 13 of 29). For circumferential outside diameter stress corrosion cracking (ODSCC) occurring near the hot leg top-of-tubesheet in the transition expansion zone, the limiting measured indication is judged to be acceptable since the maximum depth from phase angle measurement overestimates the crack depth. In this case, the flaw that contained the largest measured depth had an amplitude of 0.16 volts. The staff agrees that the low flaw amplitude seems inconsistent with the measured phase angle depth. The staff also notes that the phase angle sizing technique, based on EPRI ETSS 21410.1, was applied since a statistically acceptable correlation between signal amplitude and crack depth was not established during development of the sizing technique. Was a relationship between signal amplitude and crack depth used in other ways? For example, discuss if a site-specific probability of detection (POD) function was developed for circumferential ODSCC at this location based on use of the EPRI model assisted probability of detection Code.

Question 3

1. Identify the location(s) where Footnote 3 applies in the Operational Assessment Burst and Leakage Summary Table (page 22 of 29).

OFFICE NRR/DORL/LPL1/PM NRR/DORL/LPL1/BC NRR/DNRL/NCSG/BC NAME VSreenivas HGonzalez SBloom DATE 02/12/2024 02/12/2024 02/08/2024