NL-18-0639, Response to Request for Information Regarding Safety Relief Valve Main Valve Body Testing Extension

Response to Request for Information Regarding Safety Relief Valve Main Valve Body Testing Extension

ML18130A937
Person / Time
Site:	Hatch
Issue date:	05/10/2018
From:	Gayheart C Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-18-0639
Download: ML18130A937 (3)

Text

A Southern Nuclear Cheryl A. Gayheart Regulatory Affa1rs Director 40 Inverness Center Parkway Post Office Box 1295 B1rmmgham, AL 35242 205 992 5316 tel 205 992 7601 fax MAY 1 0 2018 cagayhea@southernco com Docket Nos.: 50-366 NL-18-0639 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant- Unit 2 Response to Request for Information Regarding Safety Relief Valve Main Valve Body Testing Extension Ladies and Gentlemen:

By letter dated August 3, 2017, and as supplemented by letters dated March 29, 2018 and April17, 2018, Southern Nuclear Operating Company (SNC) submitted a request for alternative for the Edwin I. Hatch Nuclear Plant, Unit 2 (Hatch Unit 2). The requested alternative would authorize a one-time extension of the main steam safety relief valve (SRV) main valve body (MVB) test frequency, allowing the required testing to be performed at the next Hatch Unit 2 refueling outage in February 2019.

On May 1, 2018, the Nuclear Regulatory Commission (NRC) staff and SNC staff held a conference call to clarify SNC's April17, 2018 response. By emailed correspondence dated May 8, 2018, the NRC requested additional information based on this clarification call. The Enclosure provides the additional information.

This letter contains no NRC commitments. If you have any questions, please contact Jamie Coleman at 205.992.6611.

Respectfully submitted, C.A. art Regulatory Affairs Director CAG/RMJ

Enclosure:

Response to NRC Request for Additional Information Cc: Regional Administrator, Region II NRR Project Manager- Hatch Senior Resident Inspector- Hatch RTYPE: CHA02.004

Edwin I. Hatch Nuclear Plant - Unit 2 Response to Request for Information Regarding Safety Relief Valve Main Valve Body Testing Extension Enclosure Response to NRC Request for Additional Information

Enclosure to NL-18-0639 Response to NRC Request for Additional Information NRC RAI In the course of the [May 1, 2018] discussion, SNC described how it developed and performed the MVB low pressure (400 psi), full flow test in response to the prior testing problems addressed in the Part 21 notification. SNC stated the reason that 400 psig was selected for the modified test pressure was that Target Rock had informed them that 400 psig is the lowest pressure at which the valves can be stroked. The NRC staff requests SNC to supplement its April 17, 2018 RAI response to provide that additional information on the docket.

SNC Response to NRC RAI The low pressure safety relief valve (SRV) main valve body (MVB) test was developed in conjunction with NWS Technologies. The 400 psig actuation requirement was developed through full flow (ungagged) tests at various incremental pressures starting at 50 psig and increasing up to 400 psig. During each test at incremental pressures, MVB disc stroke/travel was measured using the test stand linear variable differential transformer (LVDT). With pressure removed, the MVB was also stroked by hand to validate travel. The goal was to validate full stroke of the MVB disc (2.78-inch or greater) at the lowest pressure while eliminating rapid cycling of the disc. This goal was achieved consistently at 400 psig. At pressures lower than 400 psig, the MVB disc would open, but would either not consistently achieve full stroke or have rapid cycling following the initial stroke. These results have been replicated during 400 psig MVB testing in 2018.

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