ML22270A231

Authorization and Safety Evaluation for Alternative Request No. VR-10

ML22270A231
Person / Time
Site:	Monticello
Issue date:	09/30/2022
From:	Nancy Salgado Plant Licensing Branch III
To:	Domingos C Northern States Power Company, Minnesota
Kuntz R
References
EPID L-2022-LLR-0031
Download: ML22270A231 (5)

Text

September 30, 2022 MONTICELLO NUCLEAR GENERATING PLANT (MONTICELLO) - AUTHORIZATION AND SAFETY EVALUATION FOR ALTERNATIVE REQUEST NO. VR-10 (EPID L-2022-LLR-0031)

LICENSEE INFORMATION Recipients Name and Address: Mr. Christopher P. Domingos Site Vice President Northern States Power Company - Minnesota Monticello Nuclear Generating Plant 2807 West County Road 75 Monticello, MN 55362 Licensee: Northern States Power Company Plant Name: Monticello Nuclear Generating Plant (Monticello)

Docket No.: 50-263 APPLICATION INFORMATION Submittal Date: March 07, 2022 Submittal Agencywide Documents Access and Management System (ADAMS) Accession No.: ML22067A083 Supplement Dates: May 25, 2022, and August 29, 2022 Supplement ADAMS Accession Nos.: ML22145A588 and ML22243A175 Alternative Provision: The applicant requested an alternative under Title 10 of the Code of Federal Regulations (10 CFR), paragraph 50.55a(z)(1).

Applicable Code Edition and Addenda: American Society of Mechanical Engineers (ASME),

Operation and Maintenance of Nuclear Power Plants (OM) Code, 2017 Edition with no Addenda.

Applicable Inservice Inspection (ISI) or Inservice Testing (IST) program interval and Interval Start/End Dates: Sixth 10-year IST interval currently scheduled to begin on October 1, 2022, and end on May 31, 2032.

IST Requirement: 2017 Edition of the ASME OM Code, subsection ISTC, Inservice Testing of Valves in Water-Cooled Reactor Nuclear Power Plants, paragraph ISTC-3522, Category C Check Valves, states, in part:

Category C check valves shall be exercised as follows:

(c) If exercising is not practicable during operation at power and cold shutdown outages, it shall be performed during refueling outages [RFOs].

Paragraph ISTC-3630, Leakage Rate for Other Than Containment Isolation Valves, states, in part: Category A valves with a leakage requirement not based on an Owner's 10 CFR 50, Appendix J, program, shall be tested to verify their seat leakages within acceptable limits.

Subparagraph ISTC-3630(a), Frequency, states: Tests shall be conducted at least once every 2 yr [years].

Brief Description of the Proposed Alternative: The licensee requested U.S. Nuclear Regulatory Commission (NRC) authorization of alternative request VR-10 for the sixth 10-Year IST interval at Monticello as an acceptable level of quality and safety under 10 CFR 50.55a(z)(1). Alternative request VR-10 proposed a staggered test interval approach for the excess flow check valves (EFCVs) within the scope of this request based on the Monticello technical specifications (TSs) surveillance frequency control program (SFCP) in lieu of the 2-year test interval specified in the ASME OM Code. As described in the request, as supplemented, the sampling process for selecting EFCVs for testing and determining an appropriate test interval has a maximum test interval of 10 years for individual EFCVs.

For additional details on the licensees request, please refer to the documents located at the ADAMS Accession Nos. identified above.

STAFF EVALUATION The 2017 Edition of the ASME OM Code, subsection ISTC, paragraphs ISTC-3522 and ISTC-3630, require that ASME OM Category A valves with a leakage requirement not based on an Owners program for 10 CFR Part 50, Appendix J, Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors, shall be tested to verify that their seat leakage is within acceptable limits. Paragraph ISTC-3522(c) specifies that if exercising is not practicable during operation at power and cold shutdown outages, it shall be performed during refueling outages. Paragraph ISTC-3630(a) requires that the tests shall be conducted at least once every 2 years.

Alternative request VR-10 requests authorization of a sample-based testing approach for the EFCVs within the scope of the request as an alternative to the 2-year test interval required in the ASME OM Code. The alternative proposes to test the applicable EFCVs on a staggered sample basis at a frequency determined using the Monticello TSs SFCP. The letter dated August 29, 2022, included a 10-year maximum test interval for individual EFCVs as a modification to alternative request VR-10. The specific EFCVs within the scope of this alternative request are listed in a table in the request section Applicable ASME Code Components and/or System Description.

In a safety evaluation (SE) dated January 28, 2019 (ML19007A090) with corrections in a letter dated March 11, 2019 (ML19065A200), the NRC issued Amendment No. 200 to the Monticello Renewed Facility Operating License No. DPR-22 that revised the plant TSs to adopt Technical Specifications Task Force (TSTF)-425, Relocate Surveillance Frequencies to Licensee Control - RITSTF Initiative 5b, Revision 3, dated March 18, 2009 (ML090850642). The license amendment modified the Monticello TSs by relocating specific surveillance frequencies to a licensee-controlled program (SFCP) in accordance with Nuclear Energy Institute 04-10, Risk-Informed Method for Control of Surveillance Frequencies, Revision 1, dated April 2007 (ML071360456), which the NRC staff accepted with conditions in an SE dated September 19, 2007 (ML072570267). The license amendment request stated that the proposed TS change would be consistent with the adoption of TSTF-425. Section 2.0, Proposed Change, TSTF-425 states, in part, that all surveillance frequencies are relocated except frequencies that reference other approved programs for the specific interval, such as the IST program. Hence, the NRC staff is not reviewing in this SE the acceptability of the SCFP for application to the proposed alternative request VR-10 for the IST program at Monticello. This SE evaluates the proposed approach in alternative request VR-10 (as supplemented) to select EFCVs within the scope of the request for staggered testing during RFOs with a maximum test interval of 10 years for individual EFCVs.

The supplement to alternative request VR-10 dated May 25, 2022 (ML22145A588), provided additional information on the approach to determine the test intervals for the EFCVs within the scope of the request. The supplement stated that testing of the EFCVs would be performed on a staggered basis in conjunction with RFOs. The proposal would group EFCVs into approximately equal sized sets by several characteristics (e.g., valve manufacturer, design, service, size, and physical location, of the EFCV instrument racks) for efficient testing. The supplement indicated that the sample testing of the EFCVs will be performed at approximately equal intervals with one set of EFCVs tested each RFO until the entire population of EFCVs is tested. The supplement specified that the ASME OM Code criteria as implemented through the Monticello IST program for testing, results evaluation, and corrective action, will be followed when implementing alternative request VR-10.

Following a public meeting on July 26, 2022 (ML22208A195), the licensee provided a supplement dated August 29, 2022 (ML22243A175), to alternative request VR-10 specifying that a maximum test interval of 10 years for each EFCV will be applied based upon existing precedents for performing EFCV testing. In response to requests from licensees of other nuclear power plants, the NRC staff has authorized alternatives to the ASME OM Code for EFCV testing with a maximum test interval of 10 years (see examples ML18163A054, ML19248C707, ML21049A024, and ML22061A040). On March 14, 2000 (ML003691722), the NRC issued an SE accepting with conditions the General Electric Topical Report NEDO-32977-A, Excess Flow Check Valve Testing Relaxation (ML003729011), which specifies a 10-year maximum test interval for individual EFCVs.

Based on its review, the NRC staff finds that the licensee has justified that alternative request VR-10, as supplemented, will provide reasonable assurance of the operational readiness of the EFCVs within the scope of the request at Monticello by performing sample testing on a staggered basis during each RFO with a maximum test interval of 10 years for individual EFCVs. The NRC staff finds that the proposed alternative provides an acceptable level of quality and safety for the sample testing of the EFCVs within the scope of the request in lieu of the applicable test requirements in the ASME OM Code, subsection ISTC, paragraphs ISTC-3522 and ISTC-3630, in accordance with 10 CFR 50.55a(z)(1).

CONCLUSION As described above, the NRC staff finds that the licensee has justified that alternative request VR-10, as supplemented, will provide reasonable assurance of the operational readiness of the EFCVs within the scope of the request at Monticello by performing sample testing on a staggered basis during each RFO with a maximum test interval of 10 years for individual EFCVs. Accordingly, the NRC staff concludes that the proposed alternative provides an acceptable level of quality and safety for the testing of the EFCVs within the scope of the request, in lieu of the applicable test requirements in the ASME OM Code, in accordance with 10 CFR 50.55a(z)(1). Therefore, the NRC staff authorizes the use of alternative request VR-10 for testing of the EFCVs within the scope of the request at Monticello for the sixth 10-year IST interval, scheduled to begin on October 1, 2022, and end on May 31, 2032.

All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief or an alternative was not specifically requested, and granted or authorized (as appropriate), in the subject request remain applicable.

Principal Contributor: Gurjendra Bedi, NRR Thomas Scarbrough, NRR Date: September 30, 2022 Digitally signed Joel S. by Joel S. Wiebe Date: 2022.09.30 Wiebe 12:02:54 -04'00' Nancy L. Salgado Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation cc: Listserv

ML22270A231 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DEX/EMIB/BC NRR/DORL/LPL3/BC NAME RKuntz SRohrer SBailey (KHsu for) NSalgado (JWiebe for)

DATE 9/27/2022 9/28/22 9/22/22 9/30/22