ML23087A291
| ML23087A291 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 03/28/2023 |
| From: | Richard Guzman NRC/NRR/DORL/LPL1 |
| To: | Tom Loomis Constellation Energy Generation |
| References | |
| EPID L-2023-LLR-0011 | |
| Download: ML23087A291 (1) | |
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Richard Guzman Loomis, Thomas R:(Constellation)
Reynolds, Ronnie J:(Constellation Nuclear); Hipo Gonzalez Nine Mile Point Unit 1 - Request for Additional Information - Emergent Relief Request I5R-11 Weld Overlay on RPV Recirculation Nozzle N2E DM Weld (EPID L-2023-LLR-0011)
Tuesday, March 28, 2023 4:21:39 PM
- Tom, On March 28, 2023, the U.S. Nuclear Regulatory Commission (NRC) staff sent Constellation Energy Generation, LLC (CEG, the licensee) the subject Request for Additional Information (RAI) as a draft e-mail. This RAI is in regard to the licensees March 24, 2023, proposed alternative request (ADAMS Accession No. ML23083B991), as supplemented by "NMP1L3515, Submittal of Emergency Relief Request I5R-11 Concerning the Installation of a Weld Overlay on Reactor Pressure Vessel Recirculation Inlet Nozzle N2E Safe End-to-Nozzle [[Topic" contains a listed "[" character as part of the property label and has therefore been classified as invalid. (32-WD-208)|letter dated March 27, 2023]] (ML23086C088), to perform a weld overlay to act as a leakage barrier on recirculation inlet nozzle N2E safe end to nozzle dissimilar metal weld, in lieu of repairing as required by American Society of Mechanical Engineers (ASME) Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plants, at Nine Mile Point Nuclear Station, Unit 1 (NMP1).
The NRC staff and CEG held a conference call on March 28, 2023, to discuss clarifications on the draft RAI. Updated below is the official (final) RAI. As agreed on the call, please provide a response to these questions as soon as possible and no later than March 30, 2023. A publicly available version of this e-mail communication will be placed in ADAMS, the NRCs official document repository system. Please contact me if you have any questions concerning this request.
Richard V. Guzman Senior Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Office: O-9C7 l Phone: (301) 415-1030 Richard.Guzman@nrc.gov
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REQUEST FOR ADDITIONAL INFORMATION REQUEST FOR ALTERNATIVE TO ASME CODE REPAIR REQUIRED BY IWA-4400 FOR INSTALLATION OF A WELD OVERLAY ON REACTOR PRESSURE VESSEL RECIRCULATION INLET NOZZLE N2E SAFE END-TO-NOZZLE DISSIMILAR METAL
WELD CONSTELLATION ENERGY GENERATION, LLC NINE MILE POINT NUCLEAR STATION, UNIT 1 DOCKET NO. 50-220 EPID L-2023-LLR-0011 By letter dated March 24, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23083B991), as supplemented by "NMP1L3515, Submittal of Emergency Relief Request I5R-11 Concerning the Installation of a Weld Overlay on Reactor Pressure Vessel Recirculation Inlet Nozzle N2E Safe End-to-Nozzle [[Topic" contains a listed "[" character as part of the property label and has therefore been classified as invalid. (32-WD-208)|letter dated March 27, 2023]] (ML23086C088), Constellation Energy Generation, LLC (the licensee) requests U.S.
Nuclear Regulatory Commission (NRC) authorization of a proposed alternative, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(1), to perform a weld overlay to act as a leakage barrier on recirculation inlet nozzle N2E safe end to nozzle dissimilar metal weld, in lieu of repairing as required by American Society of Mechanical Engineers (ASME) Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plants.
During the NRC staffs review of the licensees request, the NRC staff determined that additional information is needed to complete its review, as described in the request for additional information (RAI) shown below.
Regulatory Basis: Regarding proposed alternative to code requirements, the regulation in 10 CFR § 50.55a(z)(1) requires that the licensee must demonstrate that the proposed alternative would provide an acceptable level of quality and safety.
RAI-1
In the text of the licensee submittal, on page 11 of Attachment 2, reference is made to Figures 5.1-1(a) and 5.1-1(b) which are to demonstrate the examination volume of the overlayed weld. However, Figures 5.1-1(a) and 5.1-1(b) appear to be missing from. Please supplement the original application to include these figures.
RAI-2
Under Attachment 2, Section 5.1.4 Examination, provide a basis for item 4, Ultrasonic examination will be performed to the maximum extent practicable for axial and circumferential flaws. Given this is a repaired weld with an axial flaw of 83% depth, why should the examination coverage requirements be met with less than essentially 100 percent coverage for both axial and circumferential flaws? Is it anticipated that the 83%
through-wall axial flaw will be within the examinable region covered by the examination?
RAI-3
Given the minimum depth of the overlay is 0.10-inch, provide a technical basis for the liquid dye penetrant acceptance criteria to utilize ASME Code,Section III, NB-5300, which could allow up to a 3/16 rounded indication. Has this allowed fabrication indication size been considered in the flaw growth calculation for the minimum depth of the overlay? Consider in your response the weldability issues associated with Alloy 52M material. Was eddy current testing considered for this surface examination?
RAI-4
Confirm that in accordance with N-653-2, Qualification Requirements for Full Structural Overlaid Wrought Austenitic Piping Welds, subparagraph 2.1(b), the qualification specimen set meets all requirements, including at least one specimen with overlay not thicker than 0.1 in. more than the minimum thickness, and at least one specimen with overlay not thinner than 0.25 in. less than the maximum thickness for which the examination procedure is applicable.
RAI-5
It is the staffs understanding that the leakage barrier weld overlay to be installed during Nine Mile Point, Unit 1 refueling outage N1R27 will, at the time of unit restart, restore the N2E location such that the flaw will be less than 75% through wall and the requirements of IWB-3640 will be met. Given the uncertainty in the application and design of the overlay (e.g., flaw growth analysis, non-destructive examination) utilized in the proposed design overlay which has not been generically approved by the ASME Code, and the position of NUREG-0313 and N-740-2 to recommend or require compliance with IWB-3640, the NRC staff would expect the overlayed weld to be in compliance with IWB-3640 at the time of mode change.
The NRC staff understands that based on projected growth of the flaw over the next operating cycle, the flaw may grow such that prior to refueling outage N1R28 it will exceed the less than 75% through wall requirements of IWB-3640.
Explain whether, as part of this alternative, the licensee is explicitly requesting NRC approval to not maintain compliance with the requirements of IWB-3640 for the entirety of the next Nine Mile Point, Unit 1 operating cycle. If so, supplement the original request to indicate that an alternative to meeting IWB-3640 until the units next refueling outage is being requested.
RAI-6, Section 4.0 to the licensees letter dated March 24, 2023, states, This alternative is proposed in lieu of replacement of the component or installation of a permanent full structural weld overlay (FSWOL), to ensure the leak-tight integrity of this weld until a permanent repair can be performed during refueling outage N1R28. The staff notes, however, that in Attachment 1 the licensee makes no regulatory commitment to perform a permanent repair of the N2E location in refueling outage N1R28.
Given the statement in Attachment 2, explain whether the licensee did or did not intend to include such a regulatory commitment in Attachment 1. If the licensee intends to make a regulatory commitment consistent with the noted statement from Attachment 2, revise from the original submittal to include this information.
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From: Richard Guzman Sent: Tuesday, March 28, 2023 10:48 AM To: Loomis, Thomas R:(Constellation) thomas.loomis@constellation.com Cc: Reynolds, Ronnie J:(Constellation Nuclear) Ronnie.Reynolds@constellation.com; Rossi, Matthew:(Constellation Nuclear) Matthew.Rossi@constellation.com
Subject:
Nine Mile Point Unit 1 - DRAFT Request for Additional Information - Emergent Relief Request I5R-11 Weld Overlay on RPV Recirculation Nozzle N2E DM Weld (EPID L-2023-LLR-0011)
Hello Tom, By letter dated March 24, 2023 (ADAMS Accession No. ML23083B991), as supplemented by "NMP1L3515, Submittal of Emergency Relief Request I5R-11 Concerning the Installation of a Weld Overlay on Reactor Pressure Vessel Recirculation Inlet Nozzle N2E Safe End-to-Nozzle [[Topic" contains a listed "[" character as part of the property label and has therefore been classified as invalid. (32-WD-208)|letter dated March 27, 2023]] (ML23086C088) Constellation Energy Generation, LLC (the licensee) submitted Relief Request (I5R-11), associated with the emergent repair of the reactor pressure vessel recirculation inlet nozzle N2E safe end-to-nozzle dissimilar metal weld at Nine Mile Point Nuclear Station, Unit No. 1 (NMP1).
The NRC staff has determined that additional information is needed to complete its review, as described in the request for additional information (RAI) shown below. This RAI is identified as DRAFT at this time to confirm your understanding of the information needed by the NRC staff to complete its evaluation.
Please let me know your availability for a clarification call, if needed, and I will coordinate availabilities w/the NRC technical staff. I would like to hold the call no later than March 29th to support an expedited review schedule as requested by the licensee for the return to service from the current NMP1 refueling outage.
- Thanks, Rich Guzman Sr. PM, Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Office: O-9C7 l Phone: (301) 415-1030 Richard.Guzman@nrc.gov