ML23179A210

Summary of June 5, 2023, Public Meeting with Northern States Power Company Regarding Neutron Fluence Values for Reactor Pressure Vessel Welds

ML23179A210
Person / Time
Site:	Prairie Island
Issue date:	06/28/2023
From:	Ballard B NRC/NRR/DORL/LPL3
To:	Northern States Power Co
References
Download: ML23179A210 (1)

Text

June 28, 2023 LICENSEE: Northern States Power Company FACILITY: Prairie Island Nuclear Generating Plant, Units 1 and 2

SUMMARY

OF JUNE 5, 2023, PUBLIC MEETING WITH NORTHERN STATES POWER COMPANY REGARDING NEUTRON FLUENCE VALUES FOR REACTOR PRESSURE VESSEL WELDS On June 5, 2023, a public meeting via webinar was held between the U.S. Nuclear Regulatory Commission (NRC) and representatives of Northern States Power Company, a Minnesota corporation (NSPM, the licensee), doing business as Xcel Energy. The purpose of the meeting was to discuss changes to the neutron fluence values for reactor pressure vessel welds caused by an error in a calculation and the effect on an issued relief request (RR). The meeting notice and agenda, dated May 24, 2023, are available in the Agencywide Documents Access and Management System (ADAMS) Accession No. ML23153A028. A list of attendees is enclosed.

During the meeting, the NRC staff asked questions to the licensee pertaining to the history of the weld fluence error, submittals to the NRC that may be affected by the error, and any additional analyses that may have been impacted by the change in fluence values, such as, upper shelf energy, pressurized thermal shock, etc. The licensee stated the following:

- History of the error: The error occurred in a vendor calculation in 2007 and was identified by the licensee in September 2021. The error was due to the vendor calculating fluence using the incorrect location of the weld above the core midplane, resulting in a lower (non-conservative) value for fluence. The actual value for fluence was determined to be approximately double the value calculated by the vendor in 2007. Following identification of the error, the licensee received a non-cited violation (NCV-2022011-03, ML22266A090), which the NRC inspection staff determined to be of very low safety significance.

- Submittals to the NRC that may have been affected by the error: The licensee stated the incorrect values were used in their license renewal application (ML081130666),

application for measurement uncertainty recapture power uprate (ML093650045), and RRs 1-RR-5-10 and 2-RR-5-10 (ML19164A166).

- Additional analyses that may have been impacted: The licensee stated they had performed analyses using the correct fluence values and determined the change did not result in exceeding limits for the related parameters, such as upper shelf energy, adjusted reference temperature, and pressurized thermal shock.

The licensees responses were consistent with the information in NCV-2022011-03.

The licensee stated resolution for RRs 1-RR-5-10 and 2-RR-5-10 was still outstanding and they were seeking NRC staff insights on how to address the use of the incorrect fluence value in the original submittal. The licensee has not utilized the alternative authorized in response to RRs 1-RR-5-10 and 2-RR-5-10 (ML19282A541) because Prairie Island, Units 1 and 2, are in the current inservice inspection interval until December 20, 2024. The NRC staff stated the alternative authorized in response to RRs 1-RR-5-10 and 2-RR-5-10 was under the cognizance of NRC inspection staff, and that the licensee would need to perform an evaluation to determine if a new licensing action is required to prevent potential future violations. The licensee stated they would perform the evaluation to determine if they need to resubmit the request using the new neutron fluence values.

No regulatory decisions were made during the meeting. Members of the public were in attendance as indicated on the enclosed list of attendees. No comments or questions from the public were received during the meeting. Public Meeting Feedback forms were not received.

Please direct any inquiries regarding this meeting summary to me at 301-415-0680 or Brent.Ballard@nrc.gov.

/RA/

Brent T. Ballard, Project Manager Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No(s). 50-282 and 50-306

Enclosures:

List of Attendees cc: Listserv

LIST OF ATTENDEES JUNE 5, 2023, PUBLIC MEETING WITH NORTHERN STATES POWER COMPANY PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 NEUTRON FLUENCE VALUES FOR REACTOR PRESSURE VESSEL WELDS Name Organization Brent Ballard U.S. Nuclear Regulatory Commission (NRC)

Michael Benson NRC Scott Burnell NRC Matthew Domke NRC Carolyn Fairbanks NRC Angela Guieb NRC Kevin Heller NRC Ed Miller NRC Carol Moyer NRC V Sreenivas NRC John Tsao NRC Carolyn Wolf NRC On Yee NRC Marc Anderson Northern States Power Company (NSPM)

Jeffrey Kivi NSPM Chris Koehler NSPM Michael Miller NSPM Sara Scott NSPM Aaron Eberhart Public Enclosure

ML23179A210 NRC-001 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DORL/LPL3/BC (A) NRR/DORL/LPL3/PM NAME BBallard SRohrer VSreenivas BBallard DATE 6/27/23 6/28/23 6/28/23 6/28/23