ML20085H127
| ML20085H127 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 10/01/1974 |
| From: | Eric Thomas TENNESSEE VALLEY AUTHORITY |
| To: | Case E US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20085H129 | List: |
| References | |
| AO-BFEAO-7421W, NUDOCS 8308300214 | |
| Download: ML20085H127 (3) | |
Text
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TENNESSEE VALLEY AUTHOAITY r-3q - In CHA4 a ANDOGA, TENNESSEE J[ 8
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Mr. Edson G. Case Acting Director of Licensing Office of Regulaticn U.S. Atomic Energy Commission Washington, DC 20545
Dear Mr. Case:
TENNESSEE VALLEY AUTHORITY - EROWHS FERRY NUCLEAR PIANT UNIT 1 -
DOCIET No. 50-259 - FACILITY OPERATING IlCENSE DPR ABNORFAL OCCURRENCE REPORT EFFAO-7421W The enclosed report provides details concerning the temporary loss of river te=perature record because of a component failure in the environ-mental data collection system. This event occurred on Browns Ferry Nuclear Plant unit-1 en Septemoer 21-22, 1974, and is reported in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973 Very truly yours, TENNESSEE VALIEY AUTHORITY
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[n-E.F. Thomas
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Directcr of Pcwer Production Enclosure CC(Enclosure):
Mr. Norman C. Moseley, Director Region II Regulatory Operations Office, USAEC 230 Peachtree Street, IM., Suite 818 Atlanta, Georgia 30303 g-Dby 8308300214 741001
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' ABNORMAL OCCURREUCE REPORT R port No. EFFAO-7421W Report Date: October 1, 1974 l
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1 Occurrence Date: Sept ember 21-22, 1974 4
7acility: Browns Ferry Nuclear plant Unit 1 I
Id'ntification of Occurrence t
i Watir temperatures in Wheeler Reservoir were not recorded during the period 2000 hrs CDT Ssptember21 to 0430 hrs CDT September 22, 1974.
Conditions Prior to Occurrence
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Unit 1 was in cold shutdcwn. Unit 2 load held constant at about 430 nie. River flow was 37,000 cfs at 2000 hrs CDT, decreasing to 2000 cfs at 2400 hrs CDT and r: raining there until 0800 hrs CDT, September 22. At 0900 hrs CDT it increased to 15,000 cfs and varied to 26,000 cfs during the period to 1600 hra CDT.
Water i
ttmperature at the time of occurrence was 76.9 degrees F. at the downstream monitor and 76.9 degrees F. at the upstream ronitor.
D'scription of Occurrence L
The last valid record of river water temperatures was made at 2000 hrs CDT on September 21, 1974.
At 2300 hrs CDT, calls were rade to notify the environmental data collectien system caintenance supervisor who was on call.
At 0230 hrs CDT cn September 22, water temperatures were obtained frca a boat on the reservoir Ct points upstream and downstream of the clant.
At 0340 hrs CDT, the caintenance suptrvisor was reached and raintenance personnel were dispatched to the plant.
g Thry arrived at 0415 hrs CDT and began a manual reporting of reservoir water t mperatures at 0430 hrs CDT.
These reports continued at hourly intervals from
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0700 hrs CDT until the envircnnental data collection system was restored to n:rmal operation at 1600 hrs CDT, September 22.
3 D 'lienation of Aprarent Cause of Occurrence a
1 Rivir water temperatures were not recorded because of a component failure in the 1
computer coatrolling the collection of these data.
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s Analysis of Occurrence 7
An cnalysis of all river water temperature data available prior to, during, and following this occurrence indicates that the environmental technical specification limita regarding temperature and temperature increases were not exceeded during the occurrence. These data are tabulated below:
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" Temperatura Temperature RivIr Flow
, I) ate and Time (CDT)
Upstream Downstream Delta T (cubic feet per secc-d) 9/21/742000 hrs 76.9 F.
76.9o F.
0.0 F.
37,000 0
0
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2200 hrs 25,000 2400 2,000 9/22/740230 hrs 76 76 0
2,000 0430 hrs 76.4 76.3
- 0.1 2,000 0700 hrs 76.1 75 7
-0. 4 2,000 0800 hrs 76.1 75 7
-0.4 2,000 0900 hrs 76.2 75 7
-05 15,000 1000 hrs 76.2 75 7
-05 20,000 1100 hrs 76.3 75.8
-0.5 26,000 1200 hrs 76.3 75 9
-0.4 24,000 1300 hrs 76.4 75 9
-0.5 24,000 1400 hrs 76.3 76.6 03 22,000 1500 hrs 76.5 76.7 0.2 19,000 Corrective Action Upon arrival of the environmental data collection system maintenance perscnnel, standard diagnostic procedures were initiated to locate the so' tree of the system malfunction.
It was determined that a computer circuit board had failed. A standby computer and spare circuit boards were dispatched to the environmental data statien, the defective circuit board was replaced, the software program was reins,erted into the computer, and normal operations were resumed.
Manual interrogation of the water temperature monitoring stations was begun while repairs were being made, and these ' data were reported to the plant centrol recm by telephone.
Additicnal temperatures were obtained from a boat on the river during this pericd.
A standby ecmputer and co=plete set of, spare assemblies and circuit boaMs will be maintained at the environmental data statien forready access.
Existing procedures regarding "cn-call" maintenance personnel will be reviewed to determine if changes are necessary to =inimise loss of recod during occurrences of this type.
Failure Data There M.-
been no previous failures of circuit boards in the computer controlling co% tR cf river water temperatures. The automatic reporting of these data to
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,:cntrol room has been interrupted previously by software failures 1%alwe from a.c. power outages at the environmental data station. Software m
igrovements have been cade and operation is now considered to be normal.
The' component which failed was identified as a 4K memory circuit board, NOVA Minicomputer, Data General Corporation, Southboro, Massachusetts, Part No. 35600.
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