ML19177A380

Reactor Vessel Material Surveillance Capsule Withdrawal Schedules

ML19177A380
Person / Time
Site:	Prairie Island
Issue date:	07/03/2019
From:	Lisa Regner Plant Licensing Branch III
To:	Sharp S Northern States Power Co
Kuntz R
References
EPID L-2019-LLL-0002
Download: ML19177A380 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 July 3, 2019 Mr. Scott Sharp Site Vice President Prairie Island Nuclear Generating Plant Northern States Power Company - Minnesota 1717 Wakonade Drive East Welch, MN 55089

SUBJECT:

PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 -

REACTOR VESSEL MATERIAL SURVEILLANCE CAPSULE WITHDRAWAL SCHEDULES (EPID: L-2019-LLL-0002)

Dear Mr. Sharp:

By letter dated February 4, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19036A740), Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (Xcel, the licensee) requested revision of the reactor vessel material surveillance capsule withdrawal schedules for Prairie Island Nuclear Generating Plant (Prairie Island), Units 1 and 2, in accordance with Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix H, "Reactor Vessel Material Surveillance Program Requirements," 111.B.3.

The U.S. Nuclear Regulatory Commission (NRC)staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that the modified surveillance capsule withdrawal schedule for Capsule N (Prairie Island, Unit 1), and Capsule N (Prairie Island, Unit 2), is acceptable for implementation and satisfies the requirements of Appendix H to 10 CFR Part 50 for the current 60-year license term.

If you have any questions, please contact the Project Manager, Robert Kuntz at 301-415-3733 or via e-mail at Robert.Kuntz@nrc.gov.

Sincerely/)

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Lisa'M. Regner, Acting Chief Plant Licensing Branch Ill Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-282 and 50-306

Enclosure:

Safety Evaluation cc: Listserv

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR REVISION TO REACTOR VESSEL MATERIAL SURVEILLANCE CAPSULE REMOVAL SCHEDULES FOR NORTHERN STATES POWER COMPANY PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 DOCKET NOS. 50-282 AND 50-306

1.0 INTRODUCTION

By letter dated February 4, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19036A740), Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (Xcel, the licensee) requested revision of the reactor vessel material surveillance capsule withdrawal schedules for Prairie Island Nuclear Generating Plant (Prairie Island), Units 1 and 2, in accordance with Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix H, "Reactor Vessel Material Surveillance Program Requirements," 111.B.3.

Specifically, the licensee proposed to withdraw standby capsule N from Prairie Island, Unit 1, and standby capsule N from Prairie Island, Unit 2, in accordance with ASTM E185-82.

2.0 REGULATORY EVALUATION

The regulations and guidance relevant to this request include:

Regulation 10 CFR 50, Appendix H, "Reactor Vessel Material Surveillance Program Requirements," I, states in part, that:

The purpose of the reactor vessel material surveillance program required by this appendix is to monitor changes in the fracture toughness properties of ferritic materials in the reactor vessel beltline region of light water nuclear power reactors which result from exposure of these materials to neutron irradiation and the thermal environment. Under the program, fracture toughness test data are obtained from material specimens exposed in surveillance capsules, which are withdrawn periodically from the reactor vessel.

Regulation 10 CFR 50, Appendix H, 111.B.1., states, in part:

The design of the surveillance program and the withdrawal schedule must meet the requirements of the edition of ASTM E 185 that is current on the issue date of Enclosure

the ASME Code to which the reactor vessel was purchased. Later editions of ASTM E 185 may be used, but including only those editions through 1982.

Regulation 10 CFR 50, Appendix H, 111.B.3., states:

A proposed withdrawal schedule must be submitted with a technical justification as specified in 10 CFR 50.4. The proposed schedule must be approved prior to implementation.

Administrative Letter 97-04, states, in part, that:

The Commission [U.S. Nuclear Regulatory Commission (NRC or Commission}]

found that while 10 CFR Part 50, Appendix H, 11.B.3 requires prior NRC approval for all withdrawal schedule changes, only certain changes require license amendments as the process to be followed for such approval. Specifically, those changes that do not conform to the ASTM standard referenced in Appendix H (ASTM E-185, Standard Practice for Conducting Surveillance Tests for Light-Water Cooled Nuclear Power Reactor Vessels) will require approval by the license amendment process, whereas changes that conform to the ASTM standard require only staff verification of such conformance.

3.0 TECHNICAL EVALUATION

3.1 Proposal for Prairie Island, Unit 1 The submittal for Prairie Island, Unit 1, proposed to withdraw standby capsule N at 39.90 to 43.60 Effective Full Power Years (EFPY) of operation from plant startup. As stated in the submittal, this corresponds to a neutron fluence of between 7.54 x 10 19 and 8.11 x 10 19 n/cm 2 (E > 1 MeV). The capsule withdrawal information was provided in Tables 1 and 3 of the submittal.

3.2 Proposal for Prairie Island, Unit 2 The submittal for Prairie Island, Unit 2, proposed to withdraw standby capsule Nat 40.59 to 44.29 EFPY from plant startup. As stated in the submittal, this corresponds to a neutron fluence of between 7.32 x 10 19 and 7.88 x 10 19 n/cm 2 (E > 1 MeV). The capsule withdrawal information was provided in Tables 2 and 4 of the submittal.

3.3 NRC Staff Review Surveillance capsules are withdrawn and tested periodically as designated in the withdrawal schedule. Appendix H requires that the proposed schedule be approved prior to implementation.

ASTM E185-82 defines "End of Life (EOL)" as the design lifetime in terms of years, EFPY, or neutron fluence. Table 1 in ASTM E185-82 lists the minimum recommended number of surveillance capsules and their withdrawal schedule. Table 1, Note E requires that the final surveillance capsule to be withdrawn should be withdrawn not less than once or greater than twice the peak EOL vessel fluence. For Prairie Island, Units 1 and 2, the submittal states that the 60-year design life corresponds to 54 EFPY of operation from plant startup.

For Prairie Island, Unit 1, the submittal states that the maximum reactor vessel fluence at 54 EFPY is projected to be 5.16 x 1019 n/cm 2 (E > 1.0 MeV). None of the Prairie Island, Unit 1, capsules that have already been removed have been subjected to neutron fluence equal to or greater than the maximum reactor vessel fluence projected for 54 EFPY. The submittal proposes removing Standby Capsule N at a fluence of between 7.54 x 1019 and 8.11 x 10 19 n/cm 2 . This corresponds to 1.46 to 1.57 times the peak 60-year neutron fluence. With this revised schedule, Prairie Island, Unit 1, Capsule N, is scheduled to be withdrawn not less than once nor greater than twice the EOL neutron peak fluence, consistent with ASTME185-82.

For Prairie Island, Unit 2, the submittal states that the maximum reactor vessel fluence at 54 EFPY is projected to be 5.20 x 1019 n/cm 2 (E > 1.0 MeV). None of the Prairie Island, Unit 2, capsules that have already been removed have been subjected to neutron fluence equal to or greater than the maximum reactor vessel fluence projected for 54 EFPY. The submittal propose removing Standby Capsule Nat a fluence of between 7.32 x 10 19 n/cm 2 and 7.88 x 10 19 n/cm 2 (E > 1.0 MeV). This corresponds to 1.41 to 1.52 times the peak 60-year neutron fluence. With this revised schedule, Unit 2, Capsule N, is scheduled to be withdrawn not less than once nor greater than twice the EOL peak neutron fluence, consistent with ASTME 185-82.

4.0 CONCLUSION

Based on the above evaluation, the NRC staff concludes that the revised surveillance capsule withdrawal schedule for Capsule N (Prairie Island, Unit 1) and Capsule N (Prairie Island, Unit 2) satisfy the requirements of ASTM E185-82, as it relates to the current 60-year operating period.

Therefore, the NRC staff concludes that the licensee's modified surveillance capsule withdrawal schedule for Capsule N (Prairie Island, Unit 1), and Capsule N (Prairie Island, Unit 2) is acceptable for implementation and satisfies the requirements of Appendix H to 10 CFR Part 50 for the current 60-year license term.

Principal Contributor: Joel Jenkins, NRR Date of issuance: July 3, 2019

S. Sharp

SUBJECT:

PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 -

REACTOR VESSEL MATERIAL SURVEILLANCE CAPSULE WITHDRAWAL SCHEDULES (EPID: L-2019-LLL-0002) DATED JULY 3, 2019 DISTRIBUTION:

PUBLIC PM File Copy RidsACRS_MailCTR Resource RidsNrrDorlLpl3 Resource RidsNrrDmlrMvib Resource RidsNrrLASRohrer Resource RidsNrrPMPrairielsland Resource RidsRgn3MailCenter Resource ADAMS Accession No. ML19177A380 *e-mail dated OFFICE NRR/DORULPL3/PM NRR/DORULPL3/LA NRR/DMLR/MVIB/BC NRR/DORULPL3/BC(A)

NAME RKuntz SRohrer DAIiey* LRegner DATE 6/27/19 6/27/19 6/24/19 7/03/19