L-MT-23-005, Response to the NRC Request for Additional Information Regarding the 50.55a Request Pr 08, HPCI Pump Quarterly Testing (EPID Number L-2022-LLR-0088)

Response to the NRC Request for Additional Information Regarding the 50.55a Request Pr 08, HPCI Pump Quarterly Testing (EPID Number L-2022-LLR-0088)

ML23006A277
Person / Time
Site:	Monticello
Issue date:	01/06/2023
From:	Hafen S Northern States Power Company, Minnesota, Xcel Energy
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
L-MT-23-005, EPID L-2022-LLR-0088
Download: ML23006A277 (7)

Text

fl Xcel Energy 2807 West County Road 75 Monticello, MN 55362 January 6, 2023 L-MT-23-005 10 CFR 50.55a(z)(2)

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 the NRC Request for Additional Information Regarding the 50.55a Request PR 08, HPCI Pump Quarterly Testing (EPID Number L-2022-LLR-0088)

References:

1) NSPM 50.55a Request to the NRC, " L-MT-22-052 Monticello Nuclear Generating Plant 10 CFR 50.55a Request No. PR 08, Request for HPCI Pump Quarterly Alternative", dated December 15, 2022 (ADAMS Accession No. ML22350A726)

2) Email from NRC to NSPM "Draft Request for Additional Information RE:

Monticello Nuclear Generating Plant Request PR 08, HPCI Pump Quarterly Testing", dated January 4, 2023 In Reference 1, Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM"), submitted a 50.55a request for the Monticello Nuclear Generating Plant (MNGP). The proposed request would defer the quarterly testing of components in the High Pressure Coolant Injection system until after the 2023 spring refueling outage when repairs to the 'G' SRV (Safety Relief Valve) will be completed. The NRC identified the need for additional information in Reference 2. The enclosure to this letter provides NSPM's response to Reference 2.

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 L-MT-23-005 Page2 Summary of Commitments This letter makes no new commitments and no revisions to existing commitments.

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Shawn C. Hafen Plant Manager, Monticello Nuclear Generating Plant Northern States Power Company - Minnesota Enclosure cc: Administrator, Region Ill, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC

L-MT-23-005 NSPM ENCLOSURE RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION (RAI)

REGARDING THE 50.55a REQUEST PR 08, HPCI PUMP QUARTERLY TESTING

1.0 BACKGROUND

In Reference 1, Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM"), submitted a 50.55a request for the Monticello Nuclear Generating Plant (MNGP). The proposed request would defer the quarterly testing of components in the High Pressure Coolant Injection system until after the 2023 spring refueling outage when repairs to the 'G' SRV (Safety Relief Valve) will be completed. The NRC identified the need for additional information in Reference 2. This enclosure provides NSPM's response to Reference 2.

2.0 RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION

RAI 1

The request includes a summary of the testing history for check valves HPCI-18, 20, 32, 9, and 10 for the last 10 years and indicates that the valves have no history of failures. The request also states that several of the valves have been disassembled and inspected in the last 10 years. Discuss the testing history (rather than only failures) and the reason for disassembly and inspection of these check valves.

RAI 1 RESPONSE The following table shows affected check valve testing; the biennial comprehensive test also satisfies the quarterly test. The check valve testing that will be deferred is only the open/close exercise testing that occurs when the HPCI pump runs. These check valves have no history of failure to open or close as required.

Check Test Frequency Recent Instances Results Valve of occurrence HPCI-9 Open Quarterly 9/18/2022 Satisfactory (CTO) 6/21/2022 3/22/2022 12/20/2021 Biennially 12/18/2020 Satisfactory HPCI-10 Open Quarterly 9/18/2022 Satisfactory (CTO) 6/21/2022 3/22/2022 12/20/2021 Biennially 12/18/2020 Satisfactory HPCI-18 Open Quarterly 9/18/2022 Satisfactory (CTO) 6/21/2022 3/22/2022 12/20/2021 Biennially 12/18/2020 Satisfactory Page 1 of 5

L-MT-23-005 NSPM ENCLOSURE Check Test Frequency Recent Instances Results Valve of occurrence HPCI-20 Open (BTO) Quarterly 9/18/2022 Satisfactory

& Close 6/21/2022 (CTC) 3/22/2022 12/20/2021 Biennially 12/18/2020 Satisfactory HPCI-32 Open Quarterly 9/18/2022 Satisfactory (CTO) 6/21/2022 3/22/2022 12/20/2021 Biennially 12/18/2020 Satisfactory CTO/CTC: Category C exercise test open/close BTO: Category C bi-directional exercise test open Leak tightness is managed through the corrective and preventive maintenance processes, which includes the disassembly and inspection discussed in the relief request. Leak tightness testing for the HPCI check valves occurs during refueling outages and will be performed per normal periodicity; leak tightness testing will not be deferred. The table below summarizes the preventive maintenance frequency, most recent test, and next occurrence.

Check Valve PM frequency Instances of Next Scheduled occurrence in last 10 years HPCI-9 10 years 2019 2029 HPCI-10 12 years None 2023 HPCI-18 14 years 2021* 2025 HPCI-20 12 years 2015 2027 HPCI-32 12 years 2013 2025

• HPCI-18 was disassembled due to it failing the leak tightness test in 2021. A chip found on the seat was removed, and the test was performed again with satisfactory results following the disassembly and inspection.

RAI 2

The request indicates that MOV MO-2036 has 21% open capability margin. Provide the type of valve and actuator for MO-2036 and the assumptions for calculating the open margin.

RAI 2 RESPONSE MO-2036 is a Flexible Wedge Anchor Darling 8 gate valve. The valve has a Limitorque SMB-01 actuator attached.

The 21% margin is the difference between the required thrust for opening with a maximum value at cracking load of 26,981 pounds versus the maximum seating force measured during the diagnostic test of 21,152 pounds. The 21% margin shows the difference in the actual closing thrust versus the potential maximum opening thrust required for the valve to operate.

Page 2 of 5

L-MT-23-005 NSPM ENCLOSURE

RAI 3

For HPCI pump P-209, the request states that the pump trending of flow/differential pressure, oil, and vibration are stable and within acceptable range. Provide the results of the last 3 tests to demonstrate the stable performance of the pump.

RAI 3 RESPONSE The results of the last three quarterly performances of the HPCI quarterly pump tests are provided in the following table.

Flow Flow DP acceptance Date (gpm) (psig) (gpm) DP acceptance (Psig) 3/22/2022 3150 1043 2900 to 3300 1136.1 to 929.7 7/8/2022 3150 1043 2900 to 3300 1136.1 to 929.7 9/22/2022 3000 1053 2900 to 3300 1157.0 to 946.8 Vibration data in the vertical and horizontal directions, and absolute value at the test locations, is required every two years but may be recorded more frequently. The results of the last three recorded vibration data sets are provided in the table below.

Date P3H P3V P4A P4H P4V P7H P7V P8A P8H P8V 12/18/2018 (displacement, mils) 0.638 0.146 0.325 0.602 0.162 0.480 0.315 0.261 0.369 0.259 12/22/2020 (displacement, mils) 0.5974 0.1969 .02807 0.5621 0.3457 0.2622 0.4637 0.3357 0.3816 0.2862 12/21/2021 (displacement, mils) 0.6324 0.1645 0.4785 0.6954 0.381 0.4315 0.2511 0.2388 0.3587 0.2037 Acceptable Range (mils) 1.520 0.437 0.717 1.420 0.520 1.022 0.647 0.590 0.792 0.512 Page 3 of 5

L-MT-23-005 NSPM ENCLOSURE The oil was last changed in June 2018. The last oil sample was taken on 9/22/2022. The sample results since that 2018 change have been satisfactory. The particle counts, viscosity, water content and other properties have all been at normal levels. The last three analyses are provided in the following table:

Water (%/Volume)

Total Acid Number Target: <0.0200%

(mg KOH/g Alert: 0.0200%

Date Viscosity Maximum) Alarm: 0.2000%

09/22/2022 31.61 0.14 0.0006 06/22/2021 31.70 <0.10 0.0018 09/21/2020 31.70 <0.10 0.0019 Acceptable Range 28.7 to 36.7 <0.45 Target <0.200%

RAI 4

Item 19 Full Description of Proposed Alternative, in the request states that the HPCI pump tests will be deferred in the fourth quarter of 2022 and first quarter of 2023. Explain the reference to the 2022 testing because a 10 CFR 50.55a(z) alternative to ASME OM Code test requirements cannot be implemented until authorized by the NRC.

RAI 4 RESPONSE The relief request was written to include a fourth quarter 2022 test that was originally scheduled for December 19, 2022. Applying the grace allowed by ISTA-3170, this test has a hard compliance date of January 15, 2023. The fourth quarter 2022 test remains yet to be performed and will be deferred pending approval of the relief request.

RAI 5

Item 14 Applicable ASME Code Requirements includes some strange symbols 'â in 2 places. Clarify the intention of these symbols.

RAI 5 RESPONSE The symbols of Item 14 were copied into the WRR portal as ellipses. The conversion of the ellipses to the strange symbols occurred following submission when the portal data was converted to a PDF. Item 14 should be replaced with the following:

ISTB-3400, Frequency of Inservice Tests. An inservice test shall be run on each pump as specified in Table ISTB-3400-1. That table specifies a Quarterly Group A Test for Pump Group A.

ISTA-3170, Inservice Examination and Test Frequency Grace. Components whose test frequencies are based on elapsed time per table ISTA-3170-1, which states quarterly (every 3 months) and specifies 92 days between tests.

Page 4 of 5

L-MT-23-005 NSPM ENCLOSURE ISTC-3510, Exercising Test Frequency. States in part: "Active Category A, Category B, and Category C check valves shall be exercised nominally every 3 months..."

Mandatory Appendix III-3721, HSSC [High Safety Significance] MOVs [Motor Operated Valves]. States in part: "... HSSC MOVs that can be operated during plant operation shall be exercised quarterly ..."

3.0 REFERENCES

1. NSPM 50.55a Request to the NRC, " L-MT-22-052 Monticello Nuclear Generating Plant 10 CFR 50.55a Request No. PR 08, Request for HPCI Pump Quarterly Alternative", dated December 15, 2022 (ADAMS Accession No. ML22350A726)

2. Email from NRC to NSPM "Draft Request for Additional Information RE: Monticello Nuclear Generating Plant Request PR 08, HPCI Pump Quarterly Testing", dated January 4, 2023 Page 5 of 5