05000317/LER-1981-065-03, /03L-0:on 810826,during Normal Operation,Plant Computer Failed,Rendering Incore Monitoring Sys Inoperable. Caused by High Temp in Computer Room Causing Rapid Access Disc Transmission Error.Computer Restarted When Cooled

/03L-0:on 810826,during Normal Operation,Plant Computer Failed,Rendering Incore Monitoring Sys Inoperable. Caused by High Temp in Computer Room Causing Rapid Access Disc Transmission Error.Computer Restarted When Cooled

ML20010J498
Person / Time
Site:	Calvert Cliffs
Issue date:	09/25/1981
From:	Lagiewski J, Rizzo P BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20010J494	List: 05000317/LER-1981-065, Forwards LER 81-065/03L-0 05000317/LER-1981-065-03, /03L-0:on 810826,during Normal Operation,Plant Computer Failed,Rendering Incore Monitoring Sys Inoperable. Caused by High Temp in Computer Room Causing Rapid Access Disc Transmission Error.Computer Restarted When Cooled
References
LER-81-065-03L, LER-81-65-3L, NUDOCS 8110050161
Download: ML20010J498 (2)

LER-1981-065, /03L-0:on 810826,during Normal Operation,Plant Computer Failed,Rendering Incore Monitoring Sys Inoperable. Caused by High Temp in Computer Room Causing Rapid Access Disc Transmission Error.Computer Restarted When Cooled

Event date:
Report date:
3171981065R03 - NRC Website

text

NRC F ORM 366 U. S. NUCLE AR REGULATORY COMMISSION (7 77) s LICENSEE EVENT REPORT coNTROLuLoCx:

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l lh (PLE ASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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EVENT DECCRIPTION A JD Pr40B AB C SEr ENCES I o 12 I l At 0950, during normal operation, the plant computer failoa rnnanrin,e

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the incore monitoring system inoperable (T.S. 3.3.3.2).

Commenced de-I [n[4ll creasing reactor power at 1105 per Abnormal Operating Procedure - 13.

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The computer was returned to service at 1230. The excore monitoring i

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system remained operable during this event.

• his has not been a l

lo l 7 } l repetitive event.

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S Y S' E M C AUSE C A USE COYP VALVE CODE CODE SUBCODE COYPONE NT CODE SVBCODE SU 8C O'M 1o191 I RI Bl@ W@ IC l@ l zl zl zl zl zl zl@ W@ W@

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9 la 11 11 13 1H 19 20 SE QUE N Tl AL OCCUH Hi NCE HEFOHy HEVistON

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SUPP LIE H MANUFACTUHER TAkEN ACTION ON Pt. ANT YETHOD HOURS n

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40 41 42 13 44 41 c AUSE DESCRIPTION AND CORRECTIVE ACTIONS l

11 101 l Air conditionino complpysors were securva for n nne-mnafficnrinn tme [i j i l l Iligh temperature

omputer Room resulted in Ranid Access Disc I

i,,,,, j transmission error. No failure was found. The computer was restarted I

g,y3, l when cabinet internals cooled. Maintenance Supervisors were informed l

l of this event and the need to monitor appropriate temperatures.

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STATUS s03WEH OTHE H S t T IUS DISCOV E H Y DISCOVEHY DESCHIPTION NA l

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8 9 11 17 13 PiHSONNE1 INJUHIES NUYHEH DESClllPilON I

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8 9 11 17 i O'6 0f OH DAMAGE TO F ACILI TY TYPE DE SC Hip i u )N NA l

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Do o!oob!7 on J. s. Lagiewski/P. G. Rizz PHONE:

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PDR

LER NO.

81-65/ 3L DOCKET No.

50-317 LICENSE NO.

DPR-53 EVENT DATE 08-26-81 REPORT DATE 09-25-81 ATTACRMEN,T CAUSE DESCRIPTION AND CORRECTIVE ACTIONS The cause of computer failure was high ambient Computer Room tempera-ture. The Computer Room is supplied by the Control Room Heating, Ventilating and Air Conditianing System.

No. 11 Control Room Air Conditioning Compressor had been modified in accordance with an approved Facility Change and was being tested under load on the t

'ing of the event.

Operating personnel had granted p 'rmiscion to the maintenance contractor to cycle system compressors off, allowing Control Root air temperature to rise slightly and insure a full heat load for No. 11 Compressor.

Although Control Room temperature was maintained less than 85 degrees Fahrenheit, the smaller plant Computer Room temperature reached approx-imately 87 degrees during the event.

The plant computer stopped after experiencing a Rapid Access Disc (RAD) transmission error. High ambient room temperature is believed to have caused merginal RAD circuit operation. The computer was abic to be restarted after internal cabinet temperatures were lowered following the return to full operation of the Control Rc,om Air Conuitioning System. Troubleshooting revealed no hardware or software failures.

As a temporary measure, cabinet doors on the RAD, Control and External Memory cabinets are being left open until seasonal high outside air temperatures lower. A sign is posted on the door of the Computer Room to remind pernonnel entering the room that the cabinet doors should remain open.

A copy of this event report has been distributed to plant operations and maintenance supervisors with responsibility for air conditioning system status to irfnrm them of the need to insure adequate computer cooling.

Of greater impact in preventing recurrence of this type of event are measures to increase Control Room Air Conditioning component reliability.

A survey of system problems, begun la 1980, has resulted in several planned Pacility Changes to:

1.

Increase compressor reliability.

2.

Improve system controls and indications.

3.

Add cooling capacity to improve operation in peak load conditions.

Work has begun cn changes to increase reliability of existing compressors.

New instrumentation control components are ordered. Additional capacity has been initially scheduled for completion by the end of 1982.

- ~. _ _ _