ML18152B148

Confirms NRC Granting of Enforcement Discretion on 880516 Re 880516 Reduced Auxiliary Feedwater Flow.Addl Time Requested Prior to Cold Shutdown Justified Based on Min Safety Impact & Intent of Preserving Reduced Flow Condition

ML18152B148
Person / Time
Site:	Surry
Issue date:	05/17/1988
From:	Cruden D VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
88-298, NUDOCS 8805240157
Download: ML18152B148 (2)

Text

- -

e e

. t

• VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 May 17, 1988 D. S.CRUDEN VICE PRESIDENT-NUCLEAR United States Nuclear Regulatory Commission Serial No.88-298 Attention: Document Control Desk NO/DAS:vlh R2 Washington, D.C. 20555 Docket No. 50-281 License No. DPR-37 Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNIT 2 REDUCED AUXILIARY FEEDWATER FLOW CONFIRMATION OF ENFORCEMENT DISCRETION On May 16, 1988 at 0324, Unit 2 experienced a reactor trip with a subsequent reduction in auxiliary feedwater (AFW) flow to the "A" steam generator. As a result of the loss of AFW design flow to "A" steam generator, at 0341 Unit 2 entered Technical Specffication 3.0.1 with its consequential action statements of being in hot shutdown within six hours and cold shutdown within the following thirty hours. In order to more thoroughly investigate the AFW flow reduction observed after the trip, we requested that the NRC exercise enforcement discretion regarding the time prior to placing the unit into cold shutdown. Specifically, we requested that an additional forty-eight (48) hours to cold shutdown beyond the presently specified thirty hours be granted for the purpose of testing and inspection. This letter is in confirmation of NRC granting of enforcement discretion regarding this issue on May 16, 1988, based on the justification provided herein.

Following the reactor trip, AFW flow to each steam generator was initially at the design value. Approximately ten seconds after AFW initiation, flow to the "A steam generator exhibited reduced flows. A similar reduction in AFW flow 11 to the "A" steam generator was experienced following the last reactor trip on Unit 2 on March 27, 1988. Following that event, extensive investigations and inspections at cold shutdown did not reveal a reason for the flow reduction.

The reduced flow condition was not repeatable at cold shutdown. As a consequence, the current investigations and inspections were initially being carried out at hot shutdown due to the concern that the reduced flow condition may be thermally induced and therefore, not observable at cold shutdown.

Continued testing and inspection at hot shutdown did not represent a p1ant safety concern due to the status of the other normal decay heat removal systems. AFW flow to the 8 and C" steam generators was normal throughout 11 11 11 the reactor trip and continues to remain consistent with design flow requirements. Likewise, the three Unit 2 AFW pumps remain operable. In addition, main feedwater systems are. also operable and available.

--~ol 8805240157

3::::(>51 7 ' 0 PDR ADOCK 05000281 Q DCD

I i

.I

.i We considered that the additional time requested prior to cold shutdown to be justified based on the minimal safety impact and the intent of preserving the reduced flow condition long enough to establish its root cause. Subsequent to our request, during hot shutdown testing and inspect i ans, the reduced fl ow condition self-corrected. Definitive identification of the cause of the reduced AFW flow is now pending additional testing and inspections at cold shutdown. We are presently proceeding to cold shutdown on Unit 2 to continue our investigation.

If you have any questions, or require additional information, please contact us.

Very truly yours, Cruden cc: U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, N. W.

Suite 2900 Atlanta, Georgia 30323 Mr. W. E. Holland NRC Senior Resident Inspectcir Surry Power Station