L-MT-20-024, Response to Request for Additional Information (RAI) Monticello 10 CFR 50.55a Request: Request RR-016 Associated with the Fifth Ten-Year Inservice Inspection (ISI) Interval

Response to Request for Additional Information (RAI) Monticello 10 CFR 50.55a Request: Request RR-016 Associated with the Fifth Ten-Year Inservice Inspection (ISI) Interval

ML20202A474
Person / Time
Site:	Monticello
Issue date:	07/20/2020
From:	Conboy T Northern States Power Co, Xcel Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
EPID L-2020-LLR-0022, L-MT-20-024
Download: ML20202A474 (4)

Text

fl Xcel Energy 2807 West County Road 75 Monticello, MN 55089 July 20, 2020 L-MT-20-024 10 CFR 50.55a ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Monticello Nuclear Generating Plant Docket No. 50-263 Renewed Facility Operating License No. DPR-22 Response to Request for Additional Information (RAI) Monticello 10 CFR 50.55a Request:

Request RR-016 Associated with the Fifth Ten-Year Inservice Inspection (ISI) Interval (EPID:

L-2020-LLR-0022)

References:

1. Letter L-MT-20-004, from NSPM to US NRC, 10 CFR 50.55a Request:

Request RR-016 Associated with the Fifth Ten-Year Inservice Inspection (ISI)

Interval (EPID No. L-2020-LLR-0022) (ADAMS Accession No. ML2004E769)

2. Email from NRC to NSPM, DRAFT Request for Additional Information RE:

Monticello alternative request RR-016 related to H8, H9, and H10 weld examinations, dated July 01, 2020 In Reference 1, Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter NSPM), submitted the proposal to revise the previously authorized alternative in RR-008 for the H8 and H9 welds (Reference 1) to remove the 2021 refueling outage from the scope of the authorized alternative and to apply a similar alternative to the H10 welds of the core support structure, for NRC review and approval. In Reference 2, the NRC requested additional information. The enclosure to this letter is the NSPM response to the RAI question.

Please contact Mr. Ron Jacobson at (612) 330-6542 or ronald.g.jacobson@xcelenergy.com if there are any questions or if additional information is needed.

Document Control Desk Page 2 Summary of Commitments This letter makes no new comm itments and no revisions to existing commitments.

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Site Vice President, Monticello Nuclear Generating Plant Northern States Power Company - Minnesota Enclosure cc: Administrator, Region 111, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticel lo, USNRC

L-MT-20-024 NSPM Enclosure Response to Request for Additional Information:

Monticello Nuclear Generating Plant (MNGP) 10 CFR 50.55a Request RR-016

1.0 BACKGROUND

In Reference 1, Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter NSPM), submitted the proposal to revise the previously authorized alternative in RR-008 for the H8 and H9 welds to remove the 2021 refueling outage from the scope of the authorized alternative and to apply a similar alternative to the H10 welds of the core support structure, for NRC review and approval. In Reference 2, the NRC requested additional information.

2.0 RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION NRC Question:

By letter dated February 14, 2020 (ADAMS Accession No. ML20045E769), Northern States Power Company, a Minnesota corporation doing business as Xcel Energy (NSPM, the licensee), submitted a proposed alternative to the inservice inspection (ISI) requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) for the H8, H9, and H10 welds of the core support structure at the Monticello Nuclear Generating Plant (MNGP). These welds are ASME Code,Section XI Examination Category B-N-2, Welded Core Support Structures and Interior Attachments to Reactor Vessels.

Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Paragraph 50.55a(z)(2), in lieu of performing the required ASME Code successive examinations in ASME Code,Section XI, IWB-2420(b) and (c) for the H8, H9, and H10 welds, alternative request RR-016 proposes to revise the previously authorized alternative in RR-008 (ADAMS Accession No. ML15013A036) for the H8 and H9 welds to remove the 2021 refueling outage from the scope of the authorized alternative. RR-008 also applied a similar alternative to the H10 welds of the core support structure. The alternative requested to use the proposed alternative on the basis that complying with the requirements would result in hardship or unusual difficulty without a compensating increase in quality or safety.

Section 5 Proposed Alternative and Basis for Use of RR-016 (enclosure to the submittal) claims credit for hydrogen water chemistry (HWC) mitigation against crack growth through implementation of Online Noble Metal Chemistry (ONLC). The industry group, Boiling Water Reactor Vessel and Internals Project (BWRVIP), has issued an interim guidance for BWR units that use and credit all forms of HWC by letter dated January 24, 2018 (ADAMS Accession No. ML18033A323). By letter dated July 6, 2018 (ADAMS Accession No. ML18142A019), the NRC staff evaluated this interim guidance as a supplemental safety evaluation of proprietary topical report BWRVIP-62-A (ADAMS Accession No. ML19178A131 PROPRIETARY). The interim guidance states in part that BWR units that use and credit all forms of HWC shall meet Page 1 of 2

L-MT-20-024 NSPM Enclosure the conditions and limitations of BWRVIP-62-A. In the case of plants utilizing ONLC, this means they shall meet the Category 3a NMCA [noble metal chemistry addition] parameters and implementation steps (including platinum loading) of Tables 3-5 and 3-8 [of BWRVIP A].

The alternative requested stated that water chemistry controls will be implemented per the guidelines in BWRVIP-190 BWR Water Chemistry Guidelines and BWRVIP 2019-025 2019 BWR Water Chemistry Guidelines Interim Guidance, but the staff is not clear if BWRVIP-190 and/or BWRVIP 2019-025 have incorporated the interim guidance in the January 24, 2018 letter.

Request Confirm that MNGP meets the Category 3a NMCA parameters and implementation steps (including platinum loading) of Tables 3-5 and 3-8 of BWRVIP-62-A per the January 24, 2018, interim guidance.

NSPM Response:

MNGP meets the Category 3a NMCA parameters and implementation steps (including platinum loading) of Tables 3-5 and 3-8 of BWRVIP-62-A per the January 24, 2018, interim guidance.

3.0 REFERENCES

1. Letter L-MT-20-004, from NSPM to US NRC, 10 CFR 50.55a Request: Request RR-016 Associated with the Fifth Ten-Year Inservice Inspection (ISI) Interval (EPID NO. L-2020-LLR-0022) (ADAMS Accession No. ML2004E769)

2. Email from NRC to NSPM, DRAFT Request for Additional Information RE:

Monticello alternative request RR-016 related to H8, H9, and H10 weld examinations, dated July 01, 2020 Page 2 of 2