ML20314A028
| ML20314A028 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 11/06/2020 |
| From: | Jennifer Tobin Plant Licensing Branch 1 |
| To: | David Helker Exelon Nuclear |
| Tobin J | |
| References | |
| EPID L-2020-LLR-0144 | |
| Download: ML20314A028 (3) | |
Text
From:
Tobin, Jennifer To:
Helker, David P:(Exelon Nuclear)
Cc:
Gropp Jr, Richard W:(Exelon Nuclear); Loomis, Thomas R:(GenCo-Nuc)
Subject:
Peach Bottom Verbal Relief for Penetration Nozzle (EPID: L-2020-LLR-0144)
Date:
Friday, November 06, 2020 12:03:00 PM Good morning gentlemen, On Friday, November 6th at 11:30 a.m., a call was held between NRC and Exelon staff.
Thank you all for your participation. Participants and script are noted below and will be added to public ADAMS.
Participants:
NRC: Exelon: Framatome:
James Danna David Helker David Mancier Matthew Mitchell John ONeil David Cofflin Ali Rezai Thomas Loomis Ashok Nana Jennifer Tobin Jim Cirilli Ryan Hostler Jonathan Rowley Heather Malikowski Corey Dukehart Ben Jordan Henry T. Ryan Michell Karasek Mark Weis Sailaja Mokkapati Diane Render Jacqueline Graham Matt Rector Sarah Ramos
VERBAL AUTHORIZATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION FOR relief REQUEST I5R-14 regarding ALTERNATE REPAIR OF INSTRUMENT Penetration NOZZLE N-16A on the reactor vessel EXELON GENERATION COMPANY PEACH BOTTOM ATOMIC POWER STATION, UNIT 2 DOCKET NO. 50-277 EPID: L-2020-LLR-0144 November 6, 2020
Technical Evaluation read by Matthew Mitchell, Chief of the Piping and Head Penetrations Branch, Office of Nuclear Reactor Regulation
By letter to the U.S. Nuclear Regulatory Commission (NRC) dated November 4, 2020, (Agencywide Documents Access and Management System (ADAMS) Accession ML20309B020), Exelon Generation Company (the licensee) proposed an alternative to certain requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI. The licensee submitted relief request I5R-14 to support the repair of degraded 2-inch reactor vessel (RV) instrument penetration nozzle N-16A by a half-nozzle repair method at Peach Bottom Atomic Power Station (Peach Bottom),
Unit 2, and to facilitate the return to service from the current refueling outage P2R23. The duration of the proposed alternative in this relief request is for one operating cycle (cycle 24), which is scheduled to end in the fall 2022.
Pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(2), the licensee requested NRC authorization to place into service an alternative repair for the RV instrument penetration nozzle N-16A for duration of operating cycle 24 on the basis that performing a repair in compliance with the specified ASME Code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
During the performance of a routine system leakage test in the current refueling outage P2R23, the licensee discovered a leak at RV instrument penetration nozzle N-16A. The licensee proposed to repair the degraded nozzle using a half-nozzle method to restore the pressure boundary. To support its repair option, the licensee proposed an alternative to the following ASME Code requirements, the details of which are documented in the licensees submittal:
Flaw characterization requirements of ASME Code,Section XI, IWB-3420 and IWB-3620(b), and flaw removal requirements of ASME Code,Section XI, IWA-4412 and IWA-4611.
The licensee has provided the following information to demonstrate that the structural integrity of repaired RV instrument penetration nozzle N-16A will be maintained for the duration of one operating cycle.
An evaluation of the repair design, welding, and nondestructive examination to be performed.
An evaluation of the worst-case flaws left in service in the original J-groove weld that could propagate into the RV shell.
An evaluation of potential loose parts dislodged from the degraded original J-groove weld left in service that could enter the RV during normal power operation.
An evaluation of general corrosion, crevice corrosion, and galvanic corrosion of the RV low-alloy steel that could be exposed to the reactor coolant as a result of the proposed repair method.
The NRC staff finds that the licensees evaluations collectively address the safety concerns which could be raised by the proposed alternatives to the ASME Code requirements. The NRC staff finds that repaired RV instrument penetration nozzle N-16A is acceptable for the duration of operating cycle 24 based on the information provided in the licensees submittal.
The NRC staff also finds the licensees hardship justification is acceptable because performing the repair in accordance with the ASME Code,Section XI would result in an increased radiological exposure. In addition, the NRC staff determines that the licensees proposed repair of RV instrument penetration nozzle N-16A provides reasonable assurance of structural integrity and leak tightness for operating cycle 24, which is scheduled to end in the fall 2022.
NRC Staff Conclusion read by James Danna, Branch Chief, Plant Licensing Branch I, Office of Nuclear Reactor Regulation
As Chief of Plant Licensing Branch I, I concur with the Piping and Head Penetration Branch's determinations.
The NRC staff concludes that the proposed alternative in relief request I5R-14 provides reasonable assurance of structural integrity and leak tightness of repaired RV instrument penetration nozzle N-16A. The NRC staff determines that complying with the ASME Code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(2).
Therefore, as of November 6, 2020, the NRC staff authorizes the use of request I5R-14 for operating cycle 24, which is scheduled to end in the fall 2022 at Peach Bottom, Unit 2.
All other requirements of ASME Code,Section III and Section XI for which relief was not specifically requested and authorized by the NRC staff remain applicable, including the third-party review by the Authorized Nuclear lnservice Inspector.
This verbal authorization does not preclude the NRC staff from asking additional questions and clarifications regarding relief request I5R-14 while preparing the subsequent written safety evaluation.