ML20199B294

Forwards Response to NRC 971124 RAI Which Resulted in Review of Responses to GL 95-07, Pressure Locking & Thermal Binding of Safety-Related Power-Operated Gate Valves

ML20199B294
Person / Time
Site:	Vermont Yankee
Issue date:	01/23/1998
From:	Reid D VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BVY-98-11, GL-95-07, GL-95-7, NUDOCS 9801280227
Download: ML20199B294 (3)

Text

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r VERMONT . YANKEE M)

NUCLEAR POWER CORPORATION 185 Old Ferry Road, Brattleboro, VT 05301 7002 (002) 257-5271-January 23,1998 BW 98-11 j United States Nuclear Regulatory Commission l ATTN: Document Control Desk l Washington, DC 20555

References:

(a) Letter, USNRC to WNPC, NW 97166, dated November 24,1997 (b) Letter, WNPU to USNRC, BW %-07, dated February 8,1996 (c) Letter, VYNPC to USNRC, BVY 96-81, dated June 21,1996 Letter, WNPC to USNRC, BVY 96-83, dated June 26,1996 (d)

(e) Letter, USNRC to WNPC, NW 95110, dated August 17,1995 i (f) Lotter, VYNPC to USNRC, BVY 97174, dated December 22,1997 l l

Subject:

Vermont Yankee Nuclear Power Station l License No. DPR-28 (Docket 50 271)

Response to Request for Additional information (RAl) Regarding Generic Letter 95- ,

07, " Pressure Locking end Thermal Binding of Safety-Related Power Operated Gate l Valves" 1 1

This lettei provides Vermont Yankee's response (see Attachment) to the NRC'o November 24,1997 request for additional information [ Reference (a)), which resulted frorr. your review of our responses

. [ References (b), (c) and (d)], to Generic Letter 95-07 [ Reference (e)]. The timing for submittal of this letter is consistent with our request for a 30-day extension, to January 23,1998 [ Reference (f)).

We trust that this response is satisfactory; however, should you have any questions or desire additional l

Information, please contact this office.

1 Sincerely, VERMONT YANKEE NUCLEAR POWER CORPORATION )

l' Donau A. Reid Senior Vice President, Operations I

Attachment ec: USNRC Project Manager, VYNPS USNRC Region I, Administrator Obg USNRC Resident inspector, VYNPS

- VT Department of Public Service l

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United States.Neelear Regulatory Commission License No. DPR 28 (Docket 50-271)

BVY 9811 Page A1 ATTACHMENT Responses to Request for Information Regarding Vermont Yankee Submittals on Generic letter 95-07

1. The February 8,1996 submittal states that valves V1015A/B/C/D, V10-17, and V10-18, Residual Heat Removal Pump Suction, have a safety function to close and do not have a safety function to open. Therefore, Ver, iont Yankee Nuclear Power Corporation did not include these valves in the scope of GL 95-07. These valves are opened to initiate shutdown cooling in order to cooldown the unit following a reactor shutdown. Does the licensing basis for Vermont Yankee Nuclear Power Station require that the unit be cooled down following a reactor shutdown? If so, what safety-related systems are used to accomplish the cooldown?

Valves that are required to open in order to meet 10 CFR 50, Appendix R, requirements are not in the scope of GL 95-07. The NRC staff is not requesting that you address Appendix R shutdown /cooldown requirements when responding to this request for additionalinformation.

Response

No. Based on a detailed historical review of the licensing basis for this issue, Vermont Yankee is a hot shutdown plant and is not required to schieve cold shutdown except for Appendix R aad for shutdown outside the Main Control Room as described in FSAR Section 14.5.9. Therefore, valves V10-15A, B, C and D, V10-17 and V1018 do not have a safety function to open, and were not included in the scope of GL 95-07.

' 2. The February 8,1996 submittal states that valves V10-26A, Residual Heat Removal Drywell Spray, V23-14, High Pressure Coolant injection Steam Admission, and V23 20, High Pressure Coolant injection Test, would be modified to prevent pressure locking during the 1996 refueling outage. Please confirm that these modifications were completed as scheduled.

Response

Vermont Yankee Motor Operated Vdves (MOV) V10-26A, V23-14 and V23-20 were modified in the 1996 refueling outage to preclude the affects of pressure locking. MOV V10-26A is susceptible to temperature induced pressure lockleg and was modified with a device providing a known gas volume connected to the valve bonnet, since drilling a hole in the disk could not be done. Vermont Yankee plans to perform a pressure lock test of this configuration during 1998 refueling outage to confirm the analysis. MOV V23-20 was modified by dri!!!ng a hole in one side of the dist MOV V23-14 was modified by drilling a hole in the bonnet and connecting it to the upstream piping.

3. The February 8, submittal states that valves V10-31 A/B, Residual Heat Removal Containment Spray, are not susceptible to pressure locking. Discuss why these valves are not susceptible to pressure locking. If your pressure locking evaluation assumes that upstream valves V10-26A/B do nc* leak by the seat, describe seat leakage test results that demonstrate that the valves do not leak.

- . . . . _ _ _. _ ..~ .

VERMONT YANKEE NUCLEAR POWER CORPORATION

- ~ United States Nuclear Regulatory Commission Ucense No. DFR-28 (Docket 50-271)

- BVY 9811 Page A2 -

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Response

' V10-26A & B are Appendix J leak rate tested; however, they are not tested in the' direction .

needed to stop leakage towards V10-31 A & B. Even if the V10-26A & B valves did let S, the effect '

on V10-31 A & B would be the same as single sioe pressurization from the pump since the pump is, running when V10-31 A & B are opened. These MOVs are designed to overcome the effect of single  ;

side pressurizatien.

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