ML18225A066

Response to Request for Additional Information for Alternative Requests Associated with the In-Service Testing Program for Pumps, Valves, and Snubbers Fifth and Fourth 10-Year Interval Updates

ML18225A066
Person / Time
Site:	Millstone
Issue date:	08/06/2018
From:	Daugherty J Dominion Energy Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
18-258A
Download: ML18225A066 (5)

Text

Dominion Energy Nuclear Connecticut, Inc.

Rt 156, Rope Ferry Road, Waterford, CT 06385 Dominion Energy.com AUG *o 6 2018 U.S. Nuclear Regulatory Commission Serial No. 18-258A Attention: Document Control Desk NRA/WDC RO Washington, DC 20555 Docket Nos.

• 50-336/423 License Nos. DPR-65 NPF-49 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNITS 2 AND 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR ALTERNATIVE REQUESTS ASSOCIATED WITH THE IN-SERVICE TESTING PROGRAM FOR PUMPS, VALVES, AND SNUBBERS FIFTH AND FOURTH 1o~YEAR INTERVAL UPDATES FOR UNITS 2 AND 3 By letter dated March 1, 2018, Dominion Energy Nuclear Connecticut, Inc. (DENC) requested Nuclear Regulatory Commission (NRG) approval of the alternative requests associated with the In-service Testing Program for Pumps, Valves, and Snubbers, Fifth and Fourth 10-Year Interval Updates for Millstone Power Station Unit 2 (MPS2) and Millstone Power Station Unit 3 (MPS3). In an email dated June 20, 2018, the NRC transmitted a request for additional information (RAI) related to the alternative requests.

The RAI contained three questions. DENC provided the response to two of the three questions in a letter dated July 19, 2018. The attachment to this letter provides DENC's response to the third RAI question, RAI 3P-05-1.

If you have any questions regarding this submittal, please contact Michael Whitlock at (804) 273-3123.

Sincerely, Joh . . Daugherty Site Vice President - Millstone

Attachment:

Response to Request for Additional Information for Alternative Requests Associated with the In-service Testing Program for Pumps, Valves, and Snubbers, Fifth and Fourth 10-Year Interval Updates for MPS2 and MPS3 - RAI 3P-05-1

Serial No. 18-258A Docket Nos. 50-336/423 Page 2 of 2 Commitments made in this letter: None cc: U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd Suite 100 King of Prussia, PA 19406-2713 Richard V. Guzman Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08 C 2 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station

Serial No. 18-258A Docket Nos. 50-336/423 ATTACHMENT RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR ALTERNATIVE REQUESTS ASSOCIATED WITH THE IN~SERVICE TESTING PROGRAM FOR PUMPS, VALVES, AND SNUBBERS, FIFTH AND FOURTH 10-YEAR INTERVAL UPDATES FOR MPS2 AND MPS3 -

RAI 3P-05-1 MILLSTONE POWER STATION UNITS 2 AND 3 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

Serial No. 18-258A Docket Nos. 50-336/423 Attachment, Page 1 of 2 By letter dated March 1, 2018, Dominion Energy Nuclear Connecticut, Inc. (DENG) requested Nuclear Regulatory Commission (NRG) approval of the alternative requests associated with the In-service Testing Program for Pumps, Valves, and Snubbers, Fifth and Fourth 10-Year Interval Updates for Millstone Power Station Unit 2 (MPS2) and Millstone Power Station Unit 3 (MPS3). In an email dated June 20, 2018, the NRG transmitted a request for additional information (RAI) related to the alternative requests.

The RAI contained three questions. DENG provided the response to two of the three questions in a letter dated July 19, 2018, This attachment provides DENC's response to the third RAI question, RAI 3P-05-1.

RAI - 3P-05-1

Background:

In Unit 3 alternative request P-05, the licensee requested an alternative to the requirements in ASME OM Code ISTB, Mandatory Appendix V, "Pump Periodic Verification Test Program," which require pumps to pe tested at their design basis accident flow rates credited in the Owner's' safety analysis to determine whether the pumps can meet the required pressure at these flow rates. The licensee indicated that system resistance during non-design basis loss-of-coolant accident (LOCA) conditions precludes testing the charging pumps at the design basis LOCA flow rate of 519.5 gallons per minute (gpm). The licensee indicated that it can test the charging pumps at 505 gpm (the comprehensive pump test flow rate) and that engineering calculation shows that the design basis LOCA flow rate of 519.5 gpm can be achieved if a LOCA occurs.

Issue:

1. The licensee did not describe why the flow path limits the flow rate to 505 gpm.

2. Per the requirements of the ASME OM Code, a comprehensive pump test reference flow rate of 505 gpm will result in a lower bound acceptable flow rate of 475 gpm and an alert flow rate as low as 455 gpm. Over the 10-year /ST interval, the pump may degrade to these levels. The alternative request does not demonstrate that the design basis LOCA flow rate of 519.5 gpm can be achieved for the duration of the 10-year /ST interval if the pump flow rate decreases to these levels.

Request:

1. Describe the flow path that is used to test the pumps and how the flow path resistance prevents the pump from achieving the 519.5 gpm flow rate.

2. Justify how it will be determined that the pump will be able to achieve the design basis LOCA flow rate of 519.5 gpm throughout the fourth 10-year ISTinterval considering performance could degrade to 475 gpm or 455 gpm over the 10-year

/ST interval.

DENC Response Upon receipt of the NRG request for additional information, DENG initiated a review of charging system hydraulic performance and has . determined that the requested

Serial No. 18-258A Docket Nos. 50-336/423 Attachment, Page 2 of 2 alternative is no longer required. DENG will perform the Pump Periodic Verification Test as required by the OM Code.

DENG hereby withdraws its request for approval of Alternative Request P-05, Testing Per ISTB Mandatory Appendix V.