2CAN069706, Discusses GL 95-07, Pressure Locking & Thermal Binding of Safety-Related Power-Operated Gate Valves

Discusses GL 95-07, Pressure Locking & Thermal Binding of Safety-Related Power-Operated Gate Valves

ML20140E065
Person / Time
Site:	Arkansas Nuclear
Issue date:	06/04/1997
From:	Mims D ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
2CAN069706, 2CAN69706, GL-95-07, GL-95-7, NUDOCS 9706110227
Download: ML20140E065 (3)

Text

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d i . dB-Entergy operations,Inc.

g 1448 S.R. 333 RusselMk, AR 72801

, Tel 501858-5000 a

1 June 4,1997 2CAN069706 ,

U. S. Nuclear Regulatory Commission Document Control Desk

Mail Station OP1-17 Washington, DC 20555 l

Subject:

Generic Letter 95-07 Commitment Change

[ Gentlemen:

0 By letter dated February 13,1996 (0CAN029605), Entergy Operations provided the 180 day

, response to Generic Letter 95-07, " Pressure Locking and Thermal Binding of Safety-Related

Power-Operated Gate Valves," for Arkansas Nuclear One (ANO). The ANO-2 containmer.t spray header isolation valves (2CV-5612-1 and 2CV-5613-2) were identified as being

susceptible to pressure locking. During heatup, pressure from the shutdown cooling system L could become trapped in the bonnets of the valves which could potentially prevent the valves from opening subsequent to ascension into mode 3. Entergy Operations implemented short term actions to stroke the containment spray header isolation valves prior to entering mode 3 in order to relieve any trapped bonnet pressure and committed to modify these valves by the end of the 2R12 refueling outage.

The red train containment spray header isolation valve modification (2CV-5612-1) has been completed during 2R12. Modification of the green train containment spray header isolation valve (2CV-5613 2) during the current 2R12 refueling outage would significantly lengthen the green train nnintenance outage window and thus increase the overall outage length unnecessarily. Entergy Operations has postponed the modification of the geen train containment spray header isolation valve (2CV-5613-2) until the next refueling outage (2R13) which is currently scheduled for late 1998. The 2R13 refueling outage currently has a green train maintenance outage window scheduled of sufficient duration to complete this modification. This commitment change was discussed with the ANO NRR project manager on May 29,1997.

An acceptable alternative action to modifying the green train containment spray header isolation valve is to heatup the plant on the red train of shutdown cooling in which the containment spray header isolation valve has been modified. During heatup from the last refueling ~ outage (2R11), temperature monitoring instrumentation was placed on these containment spray header isolation valves. The plant was heated up on the rod train of f 9706110227 970604 ff ADOCK 05000313 PDR 1 3 ",

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, June 4,'1997 2CAN069706 Page 2 shutdown cooling coming out of 2Ril. The instrumentation indicated that the bonnet temperature of the green train containment spray header isolation valve rose less than 5 degrees during this time. This temperature rise during heatup could induce an additional pressure rise in the bonnet of the green train containment spray header isolation valve. The additional pressure rise in the valve bonnet is insufficient to damage any of the valve components during stroking of the valve.

In order to demonstrate operability of the green train containment spray header isolation valve for operation, the valve will be stroked prior to heatup and prior ta entering mode 3. Stroking 2CV-5613-2 prior to heatup will relieve any pre-existing trapped bonnet pressure. Stroking the containment spray header isolation valve again prior to entering mode 3 will relieve any pressure buildup from heatup. These actions will prevent any pressure locking concerns.

Since the green train is physically isolated from the red train, the shutdown cooling system pressure should not repressurize the valve bonnet. Occe the containment spray header isolation valve has been stroked and the plant enters mode 3, there are no further significant sources of trapped bonnet pressure; hence, pressure locking would not be a concern during normal plant operations or during cooldown. Therefore, compensatory measures are in place in order to assure that the green train containment spray header isolation valve will not be susceptible to pressure locking concerns until the modification can be implemented during 2R13.

Should you have any questions, please contact me.

Very truly yours, l

/d D wigh. .Mims irect r Nuclear Safety DCM/nbm

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l U. S. NRC i

, kne 4, i997 l 2CAN069706 Page 3 l

s cc: Mr. Ellis W. Merschoff Regional Administrator U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 ,

Arlington, TX 76011-8064 i NRC Senior Resident Inspector Arkansas Nuclear One P.O. Box 310 London,' AR 72847 l

Mr. George Kalman ,

.NRR Project Manager Region IV/ANO-1 & 2 1

'U. S. Nucle r Regulatory Commission NRR Mail Stop 13-H-3 One White Flint North 11555 Rockville Pike Rockville, MD 20852 l

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