05000338/LER-1981-041-99, /99T-0:on 810609,annunciation for 16 Hz east-west Containment Mat Response Spectrum Recorder Illuminated & Could Not Be Reset.Cause Unknown.Recorder Will Be Replaced or Repaired During Next Cold Shutdown

/99T-0:on 810609,annunciation for 16 Hz east-west Containment Mat Response Spectrum Recorder Illuminated & Could Not Be Reset.Cause Unknown.Recorder Will Be Replaced or Repaired During Next Cold Shutdown

ML20009G203
Person / Time
Site:	North Anna
Issue date:	07/09/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009G199	List: 05000338/LER-1981-041, Forwards LER 81-041/99T-0 05000338/LER-1981-041-99, /99T-0:on 810609,annunciation for 16 Hz east-west Containment Mat Response Spectrum Recorder Illuminated & Could Not Be Reset.Cause Unknown.Recorder Will Be Replaced or Repaired During Next Cold Shutdown
References
LER-81-041-99T, LER-81-41-99T, NUDOCS 8108030425
Download: ML20009G203 (2)

LER-1981-041, /99T-0:on 810609,annunciation for 16 Hz east-west Containment Mat Response Spectrum Recorder Illuminated & Could Not Be Reset.Cause Unknown.Recorder Will Be Replaced or Repaired During Next Cold Shutdown

Event date:
Report date:
3381981041R99 - NRC Website

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U.S. NUCLEAR REGIfi.AI'9M COMMISSION LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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/V/A/N/A/S/1/ (2)

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/ / / (5)

LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT

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[L/ (6)

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DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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/ On June 9, 1981, with the unit operating at 100% power, the annunciator for the /

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/ 16 Hz east-west containment mat response spectrum recorder illuminated and

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/ could not be reset. This was the only alarm received. The triaxial time-history /

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/ accelograph for the containment mat remained operable. This is reportable

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/ pursuant to T.S. 3.3.3.3 and 6.9.2.c.

The health and safety of the general

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/ public were not affected.

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SYSTEM

CAUSE

CAUSE COMP.

VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

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/I/F/ (l'>

/X/ (12) [Z/ (13) /I/N/S/T/R/U/ (14)

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SEQUENTIAL OCCURRENCE REPORT REVISION LER/R0 EVENT YEAR REPORT NO.

CODE TYPE NO.

(17) REPORT NUMBER

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ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP.

COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER

/Z/ (18) /E/ (19)

/Z/ (20) /Z/ (21) /0/0/0/0/ (22) /Y/ (23) /N/ (24) /A/ (25) /E/2/5/9/ (26' CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

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/ The cause of the malfunction is unkr.own at the present time. The containment mat /

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/ triaxial response spectrum recorder will be replaced c repaired during the next /

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/ scheduled cold shutdown.

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FACILITY METHOD OF DISCOVERY DESCRIPTION (32)

STATUS

% POWER OTHER STATUS

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Operator Observation

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,/E/ (28)

/1/0/0/ (29) /

NA i

ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35)

LOCATION OF RELEASE (36)

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/Z/ (33)

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NA

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NA

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PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

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NA

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PERSONNEL INJURIES NUMBER DESCRIPTION (41)

/1/8/ /0/0/0/ (40) /

NA

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LOSS OF OR DAMAGE TO FACILITY M3)

TYPE

DESCRIPTION

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NA

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PUBLICITY 8108030425 810709 ISSUED DESCRIPTION (45)

PDR ADOCK 05000338 NRC USE ONLY

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NA S

PDR

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NAME CF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151

2 +

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1 -. s e

Virginia Electric and Power Company North Anna Power Station, Unit #1

Attachment:

Page 1 of 1 Docket No. 50-338 Report No. LER 81-041/99T-0

Description of Event

On June 6, 1979 with Unit 1 at 100% power, the containment mat response spectrum recorder indicated an alarm on the east-west axis at a frequency of 16 Hz.

This alarm indicated an amplitude of 2 0.099g. ; however, there was no alarm for 2 0.142g. in the same axis and frequency.

The alarm woulci not reset.

Probable Consequences of Occurrence The alarm is believed to be an equipment malfunction rather than a seismic event.

None of the other 11 frequencies for east-west axis alarmed nor were any of the 12 frequencies for the north-south or vertical axes alarmed at the time.

The triaxial time history accelograph is available in the event of seixmic activity.

There was no effect on the public health or safety.

Cause of Event

The cause of the alarm is unknown presently.

Containment entry to investigate this problem is not practical with the unit power due to the high radiation level.

Immediate Corrective Action

fr

,cempt was made to reset the alarm.

The problem was verified to origta.,e from the field sensor inside the containment.

l Scheduled Corrective Action I

The containment mat response spectrum recorder will be repaired or replaced during the next cold shutdown.

Actions Takan to Prevent Recurrence l

l No further action is required.

Generic Implications l

There are no generic implications.

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