RC-97-0255, Forwards Supplemental Response to GL 95-07 to Address Pressure Locking & Thermal Binding Issues Identified in NRC Integrated Insp Rept 50-395/97-01

Forwards Supplemental Response to GL 95-07 to Address Pressure Locking & Thermal Binding Issues Identified in NRC Integrated Insp Rept 50-395/97-01

ML20198B157
Person / Time
Site:	Summer
Issue date:	12/29/1997
From:	Gabe Taylor SOUTH CAROLINA ELECTRIC & GAS CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
50-395-97-01, 50-395-97-1, RC-97-0255, RC-97-255, NUDOCS 9801060214
Download: ML20198B157 (4)

Text

- - . . . . . -. . - -.

• " NUsth Carolina Electric & Gas Comparty Gary J. Taylor .

INa7Npa$tions y .y290ss

. Aanmu % - December 29,1997 4 RC 97-0255 Document Control Desk U. S. Nuclear Reg 'Jetory Commission

. . Washington, DC 20555:

Gentlemen:

Subject:

VIRGIL C. SUMMER NUCLEAR STATION (VCSNS)-

DOCKET NO. 50/395 OPERATING LICENSE NO. NPF-12 SUPPLEMENTAL INFORMATION.- GENERIC LETTER 95 07,

" PRESSURE LOCKING AND THERMAL BINDING OF SAFETY-RELATED POWER OPERATED GATE VALVES" OF JULY 3,1998 Pursuant to your request for supplementalinformation during inspection 97-01, South Carolina Eloctric & Gas Company (SCE&G) is submitting the attached documentation 1

under oath of affirmation.

Should you have any questions, please call Mr.Jeffrey W. Pease, at (803) 345-4124, at your convenience.

Very truly yours, n

b '

Gary J. Ta o GJT/SAB/JWP

' Attachment c: J. L. Skolds (w/o attachments) R. B. Clary MSo(

~

R. R. Mahan (w/o attachments) S.F.Fipps \

R. J. White - K.R. Jackson 1 A. R. Johnson NSRC

'L.A.Reyes _ File (815.14)

NRC Resident Inspector RTS (LTR950007) o J.B.Knotts Jr. ,

DMS (RC-97-0255

{ lgjg'-

PoR2188M ou!o%

P , .

PDR ,

NUCLEAR EXCELLENCE - A SUMMER TRADITIONI

i

~

l ,.

' Document Control Dosk GL S50007 RC 97-0255 Page 2 of 2-STATE OF SOUTilCAROLINA  :

TO WIT :

COUNTY OF FAIRFIELD  :

Ihereby cert'!y that a the M day d h- 1931, before me, tL ,obscriber, a Notary Public d the State d South Carolina persmally appeared David A. La/igne, being dulv sworn, and states that he has signature suthority for the Vice Presideut, Nuclear Operatims d the South Carolina Electric & Gr.s Company, a corporatim d the State d South Carolina, that he provides the foregoing response for the purposes therein set forth, that the statements made are true ard correct to the best d his knowledge, informatim, and belief, and that he was authaized to provide the response on behalf cf said Corporation.

WITNESS my Hand wi Nottrial Seal

/ NotaryPublic My Commission Expires ,Yd

/7 zog 7

~ 11 ate m 1 s

1

Eociosura to Docum^nt Control Desk

. .. RC 97-0255 Page 1- of 2 VCSNS SUPPLEMENTAL RESPONSE TO GL 95-07 PURPOSE:

This enclosure provides the supplemental response to GL 95-07 to address the Pressure Locking (PL) and Thermal Binding (TB) issuec identified in NRC Integrated Inspection Report 50-395/97-01.

Pt and TB issues identified in NRC Inspection Report 9741:

The inrpectors concluded that the evaluations for valves XVG08884-SI (High Head Safety injection to RCS Hot Legs), XVGOS885-SI (Alternate High Head Safety injection to RCS Cold Legs), XVG08886-Si (High Head Safety injection to RCS Hot Legs) and XVG08889-SI (Low Head Safety injection to RCS Hot Legs) for PL; and the evaluations of valves XVG08000A,B,C-RC (Pressurizer PORV Block) for TB were currently insufficient to meet the intent of GL 95-07. The following are the specific issues identified and the VCSNS resolution:

1. "The actuator capability for valve XVG08885-Si was satisfactory for the short term but

? was marginal and should not be considered as loogterm corrective action to preclude PL A low disk coefficient of friction was used in its PL calculation and the margin -

t:etween actuator capability and valve PL thrust requirements were minimal".

VCSNS Resolution - Valve XVG08885-Si will be modified by the end of the next refueling outage (RF-11) to increase the opening thrust margin. An opening thrust margin of greater than 20% will be considered acceptable for the long-term corrective action. The opening thrust margin will be determined based on the difference between the PL thrust requirements and the actuator capability. The PL thrust requirements will be calculated consistent with the Commonwealth Edison methodology us;ng the Design Basis valve factor. The static pullout force used in the PL calculation will include diagnostic equipment errors.

2. "The licensee's PL calculations for valves XVG08884-SI, XVG08886-Si and XVG08889-SI assumed that bonnet leakage over an eight hour period would reduce the amount of thrust required to overcome PL and concluded that the valves could ,

- overcome potential PL". The report goes on to state "The inspectors concluded that

Epclosuro to Docum:nt Control Desk

, . RC-97 0255 Page 2 of 2 the licensee could not demonstrate that the Westinghouse analysis bonnet depressurization rates were applicable to their flexible wedge gate valves. Therefore, the capabilities of valves XVG08884 SI, XVG08886-Si and XVG08889-SI to overcome PL were in question". The report also states that the PL issues with the valves were satisfied for the short-term but long-term corrective actions are required.

VCSNS Resolution - Valves XVG08884-Si and XVG08886-Si will be modified by the end of the next refueling outage (RF-11) to increase the opening thrust margin. An opening thrust margin of greater than 20% will be considered acceptable for the long-term currective action. The opening thrust margin will be determined based on the difference between the PL th .st requirements and the actuator capability.

The PL'.brust requirements will be calculated consistent with the Commonwealth Edison methodology using the Design Basis valve factor. The static pullout force ueed in the PL calculation will include diagnostic equipment errors. The bonnet pressure, used to determine the thrust required to overcome PL, will take no credit for any bonnet leakage /depressurization. Valve XVG08889-SI will be modified as necessary by the end of RF-11 to eliminate the potential PL condition.

3. "The licensee's GL 95-07 submittals stated that valves XVG08000A,B,C-RC were not susceptible to thermal binding because the valves had been closed nurnerous times and reopened at a lower temperature without experiencing any problems. However, when the inspectors reviewed the history of these valves, they found the licensee did not have adequate historical data on tne valves' wedging and unwedging forces to support this conclusion". The repod goes on to state "Therefore, the inspectors were unable to determine il these valves were susceptible to thermal binding under the current actuator setup conditions".

, VCSNS Resolutlore - VOSNS does not consider the PORV Block valves to be susceptible to TB as stated in our previous GL 95-07 submittals.

To resolve this issue however, station procedures will be revised to require cycling a Pressurizer PORV Block valve approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after it is closed to isolate a leaking PORV. Cycling the PORV Block valve approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after being closed to isolate a leaking PORV will verify the Block valve is not thermally bound. Pressurizer PORV Block valves that have been closed with the power removed will not be cycled. The PORV Block valves are not required to be opened for Cold Over Pressure Protection. The procedure revisions will be completed within 8 weeks of the receipt of NRC concurrence of the corrective actions in this submittal.

__