ML20155J230

Special Rept:On 880910,containment Mat Triaxial Response Spectrum Recorder Inoperable for More than 30 Days.Repairs to Alarm Circuit of Recorder Will Be Performed During Unit 1 1989 Refueling Outage

ML20155J230
Person / Time
Site:	North Anna
Issue date:	10/20/1988
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
88-699, NUDOCS 8810250406
Download: ML20155J230 (2)

Text

- .

.s .

VIHolNIA ELucTHIC AND POWEN COMPANY l

Hrcnxoxo,Vinorxtr 20201  !

Octeer 20, 1988 United States Nuclear Regulatory Commission Serial No.88-699 Attention: Document Control Desk NAPS /JHL Washington, D. C. 20555 Docket No. 50-333 License No. NPF-4

Gentlemen

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT P'O. 1  :

CONTAINMENT MAT TRIAXIAL RESPONSE SPECTRUM RECORD 1B At 0600 on September 10, 1988, with Unit 1 et 100 percent power (Mode 1) and  ;

the containment mat triaxial response spectrum recorder inoperable, the Action

• Statement of Technical Specification 3.3.3.3 was entered. The Actinn Statement requires that the saismic monitoring instrument be returned to operable status within 30 days or prepare and submit a Special Report to the Commission pursuant to Specification 6.9.2 within the next 10 days outlining the cause of the malfunction ~nd plans for restoring the instrument to operable status. Since i..k e containment mat triaxial response spectrum recorder was still inoperable on October 10, 1988, this Special Report is being submitted pursuant to Technical Specification 6.9.2.

On September 10, 1988, control room personnel otderved various annunciators un the control room seismic instrument panel to be in alarm. The Instrument Department was notified to troubleshoot the alarms. Troubleshooting determined that there may be either a bad capacitor or a leakage to ground connection in the alarm circuit for the vertical portion of the containment mat triaxial response spectrum recorder. The leads have since been lifted to defeat the continuous alarms in the control room. The vertical recorder is still operable, but without control room indication. The north-south and east-west recorders and annunciators for the containment mat triaxial response spectrum recorder are still operable. In addition, there are other seismic monitoring instruments that provide control room indication in the event of a seismic event (i.e., the containment mat and containment operating level triaxial time history accelerographs and the containment mat triaxial seismic switches).

Repairs to the alarm circuit of the vertical portion of the containment mat triaxial response spectrum recorder will be performed by the recorder -

manufacturer (Engdahl Enterprises) during the Unit 1 1989 refuel ng outage pamn 31%* p s

i o

which is scheduled to commence in April 1989. The recorder is a very sensitive instrument. Past experiences with repairs on this recorder at ,.

power, which requires commensurai.e protective clothing, self contained breathing apparatus and limited access time because of ALARA concerns, have resulted in damage to the equipment. Performing the repairs during the refueling outage will reduce the potential for further damage of the recorder, i No significant safety implications are posed by this event because other '

Technical Specification seismic monitoring instrumentation with control room indication is operable.

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

Ve y t ul  :

!' [

W. R. Cartwright Vice President - Nuclear cc: U. S. Nuclear Regulatory Commission 101 Marietta Street, N. W.

Suite 2900 ,

Atlanta, Georgia 30323 l

Mr. J. L Caldwell NRC Senior Resident Inspector North Anna Power Station i

l

_ _ _ . _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _