ML23088A388
| ML23088A388 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 04/03/2023 |
| From: | Dawnmathews Kalathiveettil NRC/NRR/DORL/LPL2-1 |
| To: | Southern Nuclear Operating Co |
| References | |
| EPID L-2022-LLA-0120 | |
| Download: ML23088A388 (1) | |
Text
April 3, 2023 LICENSEE:
Southern Nuclear Operating Company, Inc.
FACILITY:
Edwin I. Hatch Nuclear Plant, Units 1 and 2
SUBJECT:
SUMMARY
OF MARCH 28, 2023, OBSERVATION PUBLIC MEETING HELD WITH SOUTHERN NUCLEAR OPERATING COMPANY, INC., REGARDING A LICENSE AMENDMENT REQUEST FOR THE REACTOR PRESSURE VESSEL HEAD CLOSURE BOLTS FOR EDWIN I. HATCH NUCLEAR PLANT, UNITS 1 AND 2 (EPID NO. L-2022-LLA-0120)
On March 28, 2023, an Observation meeting was held between the U.S. Nuclear Regulatory Commission (NRC) and representatives of Southern Nuclear Operating Company, Inc. (SNC, the licensee). The purpose of the meeting was to discuss the license amendment request (LAR) regarding the reactor pressure vessel (RPV) head closure bolts for Edwin I. Hatch Nuclear Plant (Hatch), Units 1 and 2.
By letter dated August 19, 2022, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22231B055), as supplemented by letter dated January 20, 2023 (ML23020A902), SNC submitted a LAR to relax the required number of fully tensioned RPV head closure bolts in Technical Specification (TS) Table 1.1-1, MODES, of each of the TSs for Hatch, Units 1 and 2.
A list of attendees is provided as an Enclosure 1.
On March 3, 2023 (ML23062A318), the meeting was noticed on the NRC public webpage.
The NRC staff opened the meeting with introductory remarks and a roll call of the attendees.
The two main areas of discussion included:
Discussion about SNCs RPV head closure bolts out of service TS usage and definition, and Discussion about the maximum allowable torque that will be applied during tensioning of an indication RPV head closure bolt prior to plant start-up.
The NRC staff brought up the following discussion topics:
- 1. The Hatch submittal uses the term out of service extensively in describing the proposed TS changes for RPV bolts. Please provide an explanation of SNCs proposed use of out of service in the TS as compared to the current TS OPERABLE-OPERABILITY definition.
- 2. In the January 20, 2023, submittal, the licensee states that it fully intends to employ sound engineering principles to maintain all RPV studs in service. If a flaw is found during a Section XI inspection in an RPV bolt that will not be repaired or replaced, what are the licensees requirements (e.g., repair/replace), as part of its sound engineering principles, to determine the maximum allowable torque that will be applied during tensioning of that bolt prior to plant startup?
The NRC staff sought to understand the usage of the proposed TSs. In particular, the NRC staff questioned the definition of out of service. The NRC staff asked whether out of service meant to include two aspects that (1) the bolt could not be fully tensioned or (2) the bolt could not be properly examined in accordance with Table IWB-2500-1 of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME BPV Code),Section XI. The NRC stated that this interpretation would be consistent with the supporting analysis of stresses in the RPV head flange.
Hatch, Unit 2, RPV head closure bolt #33 has an indication that SNC could not characterize in accordance with the ASME BPV Code,Section XI, because the bolt could not be removed. The NRC staff noted that it granted SNC a relief request dated August 10, 2017 (ML17205A345), for bolt #33 from refueling outage 2R24 to the beginning of refueling outage 2R25. At Hatch, Unit 2, the NRC also granted SNC a relief request dated February 6, 2019 (ML19035A550), for bolt
- 33 until December 31, 2025.
Despite the approved relief requests above, the NRC staff questioned the adequacy of the proposed TSs to ensure the structural integrity of the RPV and leak-tightness of the primary system pressure boundary, because the proposed TS would allow the plant to operate with two un-tensioned bolts beyond 2025 for the remaining plant life. The NRC staff asked if bolt #33 would be considered to be out of service, because SNC could not complete the ASME BPV Code,Section XI requirements for bolt #33 (e.g., the bolt could not be examined and an indication could not be characterized), so bolt #33 cannot be conclusively demonstrated to be acceptable for continued service. The NRC staff asked how the proposed TSs would prevent two bolts (either un-tensioned or not meeting ASME Section XI) from being less than 9 bolts apart, the assumption in SNCs supporting analysis.
SNC presented a proposed revision to the current proposed TS (see Enclosure 2). The proposed revision was discussed. The NRC asked how the proposal would address the above question, but the NRC staff did not make any regulatory decisions regarding this proposed TS revision. SNC stated that it plans to revise the TS wording.
The following questions 3 - 6 will be discussed at a future public meeting.
- 3. If approved, the proposed TS changes would appear to allow one bolt from Unit 1 and two bolts from Unit 2 not to be installed or installed and not fully torqued. Please explain how this does not constitute a material alteration of the facility as originally designed and licensed. Based on the above, please justify the assertion that no hardware changes are proposed if the proposed change would allow operation with up to two RPV head closure bolts not installed or torqued.
- 4. Operational history of nuclear power plants does not appear to provide a sufficient technical basis to support the assertion that vessel head bolt failure or degradation is a condition that warrants preemptive analytical consideration. NRC staff has concern that all vessel head bolts should be in full service unless degradation in a bolt is found and the operational condition is sufficient to justify an alternative vessel head closure bolt tensioning TS. Based on the lack of operating experience and monitoring data, please justify the technical basis for the assumption of an additional bolt being out of service beyond bolt #33 in Unit 2 or any bolt out of service in Unit #1 for the life of the plant.
- 5. Please describe how Hatch maintenance rule implementation and aging management programs capture the Hatch vessel head closure bolts and justify a TS change.
- 6. Please justify requesting approval of any scenario of bolt degradation beyond that involving bolt #33 in Unit 2 and explain the tensioning of the Unit 2 vessel head closure bolts coming out of the spring 2023 Unit 2 refueling outage. Based on the completed Unit 2 outage, please justify the continuing need for the proposed amendments.
There was one member of the public in attendance.
The NRC staff did not make any regulatory decisions during the meeting. Once a regulatory decision is made, the NRC staff will provide SNC the regulatory decision in writing in a timely manner. Public Meeting Feedback forms were available, but no comments were received.
The meeting adjourned at 8:54 am Eastern Time (ET).
Please direct any inquiries to me at Dawnmathews.Kalathiveettil@nrc.gov or 301-415-5905.
/RA by John Lamb for/
Dawnmathews Kalathiveettil, Project Manager Plant Licensing Branch, II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-321 and 50-366
Enclosures:
- 1. List of Attendees
- 2. SNC Marked Up TS Page cc w/encls: Distribution via Listserv
LIST OF ATTENDEES MARCH 28, 2023, PUBLIC MEETING WITH SOUTHERN NUCLEAR COMPANY REGARDING A REACTOR PRESSURE VESSEL HEAD CLOSURE BOLTS LICENSE AMENDMENT REQUEST EDWIN I. HATCH NUCLEAR PLANT, UNITS 1 AND 2 ATTENDEE REPRESENTING John G. Lamb U.S. Nuclear Regulatory Commission (NRC)
Mike Markley NRC Ravi Grover NRC John Tsao NRC Thomas Scarbrough NRC Dave Dijamico NRC Stew Bailey NRC Kamal Manoly NRC Vic Cusumano NRC Kaihwa Hsu NRC Angie Buford NRC David Rudland NRC Adam Quarles Southern Nuclear Operating Company (SNC)
Ryan Joyce SNC Chris Dunham SNC Cole Cauthen SNC Jimmy Collins SNC John Broussard Dominion Engineering Inc. (DEI) - SNC Contractor Steve Wideman SJW Consulting - SNC Contractor Tim Enfinger Public
PRELIMINARY DRAFT Definitions 1.1 HATCH UNIT 2 1.1-8 Amendment No.
Table 1.1-1 (page 1 of 1)
MODES MODE TITLE REACTOR MODE SWITCH POSITION AVERAGE REACTOR COOLANT TEMPERATURE
(°F) 1 Power Operation Run NA 2
Startup Refuel(a) or Startup/Hot Standby NA 3
Hot Shutdown(a)
Shutdown
> 212 4
Cold Shutdown(a)
Shutdown 212 5
Refueling(b)
Shutdown or Refuel NA (a)
All required reactor vessel head closure bolts fully tensioned. The required number of head closure bolts is at least 54 of 56 bolts, with a minimum of nine bolts between the two out of service bolts.
(b)
One or more required reactor vessel head closure bolts less than fully tensioned.
fully tensioned less than fully tensioned
PKG: ML23088A228 Meeting Notice: ML23062A318 Meeting Slides: ML23088A236 Meeting Summary: ML23088A388 OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DEX/EMIB/BC NAME DKalathiveettil (JLamb for) KGoldstein SBailey DATE 03/28/2023 04/03/2023 04/03/2023 OFFICE NRR/DORL/LPL2-1/BC NRR/DORL/LPL2-1/PM NAME MMarkley DKalathiveettil (JLamb for)
DATE 03/30/2023 04/03/2023