ML20085G261

AO BFEAO-7422W:on 741202,water Temps in Wheeler Reservoir Not Recorded.Caused by Failure in Computer Controlling of Data Collection.Standby Computer Spare Memory Board Interchanged W/Existing Memory Board

ML20085G261
Person / Time
Site:	Browns Ferry
Issue date:	12/12/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
References
AO-BFEAO-7422W, NUDOCS 8308240731
Download: ML20085G261 (3)

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'. . .O O AB:!OEAL OCCURREriCE REPORT Report tio. : 3FEAO-7422W Report Date: December 12, 1974 Occurrence Date: December 2, 1974 Facility: Browns Ferr/ Nuclear Plant Identification of Occurrence Eter te=peratures in Wheeler Reservoir were not recorded during the period 0100 CST to 0815 CST en December 2, 1974 {

Conditions Prior to Occurrence Unit 1 load held constant at 1030 IG'e and unit 2 load at 650 We. River flow was 21,000 cfs at 0100 CST, decreasirq to 19,000 cfs at 0300 CST, then increasing to 46,000 cfs at 0815 CST cn December 2. Water terperature at the time of occurrence .. ..

vas 49 7 F at the downstream monitor and 49.6oF. at the upstream monitor.

Description of Occurrence Tns last valid record of river water te=peratures was made at 0045 hours5.208333e-4 days <br />0.0125 hours <br />7.440476e-5 weeks <br />1.71225e-5 months <br /> CST on December 2, 1974 At 0730 hours0.00845 days <br />0.203 hours <br />0.00121 weeks <br />2.77765e-4 months <br /> CST, the environnental data collection system

=cintener.ce s'iperviser was n0tified. I'.aintenance personnel were i=:.ediately dispatched to the plant arriving at 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> CST c d began a manual reporting of reservoir water te=peratures at 0815 hours0.00943 days <br />0.226 hours <br />0.00135 weeks <br />3.101075e-4 months <br /> CST. Additional reports were made at 0915 hours0.0106 days <br />0.254 hours <br />0.00151 weeks <br />3.481575e-4 months <br /> CST. The environ = ental data collection system was restored to normal operation at 1000 hcurs CST cn December 2,1974 Designation of Anoarent Cause of Occurrence River water terperatures were not recorded because of a failure in the co:puter contro111rq the collection of these data.

Analvsis of Cecurrence An analysis of all river water te=perature data available before and following this occurrence indicates that the Environmental Technical Specification limits regarding tc=perature and terperature increases were not exceeded during the occurrence.

Tnese data are tabulated on the following tabic:

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.t Temperature Te=perature Date and Time Unstrea= Downstrea=- Delta T River Flow CST G7 0F cF cubic feet per second 12/1/74,2400 hrs 49.7 49 7- 0 27,000 12/2/74,0045 hrs 49.6 49 7 + .1 0100 hrs 21,000 0200 hrs 19,000 0300 hrs 19.000 0400 hrs 19,000 0500 hrs 20,000 0600. hrs 28,000 0700 hrs 40,000 0815 hrs 46,000 0915 hrs 49,000 1000 hrs 51,000 Corrective Action Upon arrival of the environrental data collection system maintenance personnel, the standby co=puter spare ne=crf board was interchanged with the existing memory board and nor:21 operations resumed. The standby memory board had been soft 2re program loaded and maintained at the environnental' data station for just such ready access situations.

Failure Data The memorf board malfunction, as verified by dia6nostic test program, was not a hardware failure. Further tests on software program indicated that an electrical transient condition resulted in changing the program information in so=e me=ory locations.

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TENNEE5*35 VALLEY AUTMCTITY r * ~'

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- m r DEC161974 m. E w r'n, ur A Vr. Edson G. Case b u s "* ,;!I Acting Director of Licensing "kwar Office of Regulation 4 "** {p p

U.S. Atcmic Energy Cec =ission 4. -[\

Washington, DC 20545

Dear V.r. Case:

TEEESSEE VATT Y AUTHORITY - BROE7ES FERRY NUCLEAR FIA'iT UNIT 1 - DCCET I!O. 50-259 - FACILITY OPERATING LICHISE DPR AEIiCFl'AL CCCURREIICE REPORT BFEAO-7422W The enclosed report provides details concerning the -

failure to reccrd river water temperatures because of a ralfuncticn in the ec=puter controlling the collection of these data. This event cccurred at P2cwns Ferry Nuclear Plant en December 2,1971, and is repcrted in acecrdance with Appendir. A to Regult.tcry Guide 1.16, Revision 1 3 Octcber 1973 Very truly yours, TCHESSEE VALLEY AUTHORITY

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, Directcr cf Pcwer Producticn .

Enclosure CC (Enclosure):

Fr. licrcan C. Mcseley, Direcher Region II Regulatory Operations Office, USAEC 230 Peachtree Street, IM., Suite 818 Atlanta, Geergia 30303-W

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