ML18283A852

LER 1977-771-00 for Browns Ferry Nuclear Plant, Unit 1, Reservoir Water Temperature Exceeding Maximum Temperature Rise of 5 Degrees F on 02/03/1977

ML18283A852
Person / Time
Site:	Browns Ferry
Issue date:	02/14/1977
From:	Gilleland J Tennessee Valley Authority
To:	Moseley N NRC/RGN-II
References
Download: ML18283A852 (13)

Text

U.S. NUCLEAR REGULATORY Co ION DOCKET NUMBER NRC FORM 195 (2-7B) C o- re(

FI E NUMBER NRC DISTRIBUTION FoR PART 50 DOCKET MATERIAL TO: Mr N C Moseley FROM: Tennessee Valley Authority DATE OF DOCUMENT Chattanooga, Tn 2-14-77 J E Gilleland DATE RECEIVED 2-23-77

@LETTER CINOTORIZED PROP INPUT FORM NUMBER OF COPIES RECEIVED QORIGINAL IRUNCLASSIFIE 0 3ICOP Y lcc DESCRIPTION ENCLOSURE Ltr trans the following: Licensee Event Report (RO/II 771) on 2-3-77 which concerni Appendix B violation with regard to reservoir water temperature exceedin tech specs limitations.......

lp ppgg,Q Q$)~pp PLANT NAME'rowns Ferry FOR ACTION/INFORMATION

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-'6g ~,. 830 P<FFFF.r Building TENNESSEE VALLEY AUTHORlTY CHATTANOOGA, TENNESSEE 37401 5~

b February 14, 1977 "PPS.1@+

Ih. Norman C. HoseleyDirector ~;.~jq jlgig~~>> gOCIrtef It Nuclear Regulatory Commission III'.S.

Region II 230 Peachtree Street, Rf., Suite 1217 Atlanta,, Georgia 30303

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Dear Nr; Moseley:

TENNESSEE V~

DOCKET NO. 50-259 AUTHORITY

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BROWS FERRY NtJCLEAR PLQF2 UNXT FACILXTY OPERATING LICENSE DPR-33 ENVIRON-1-

MENTAL REPORTABLE OCCUREKNCE BFERO-50-259/773, The enclosed. report is to provide details concerning the reservoir vater temperature .exceeding the maximum temperature rise of 5 degrees F on February 3, 1977. This report supplements our telecopy to you on February 3, 1977, from H. J. Green, This report is submitted i.n accordance vith Brovns Ferry Technical Specgfication 5.6.3b. This event occurred on Brovns Ferry Nuclear Plant unit 1.

Very truly yours',

J. E. GilloFland Assistant Ravager of'over Enclosure (3) IF

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. Director g /p Division of Operating Reactors o'~Zg

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U.S. Nuclear Regulatory Commission 19pp, co ltashington, DC 20555 Ig Pg Director (3)

Office of Management Information and. Program Control U.S. Nuclear Regulatory Commission Washington, DC 20555 Director (40)

Office of Xnspection and, Enforcement U.S, Nuclear Regulatory Commission Uashington, DC 20555 CP~+~oO

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,CS An Equal Opportunity Employer

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CONTI40L BLOCI(:~ J (PLEASE PRINT ALL REOUIREO INFORMATION)

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8 9 6G FACILITY METHOD OF STATUS PDWEA OTHER STATUS DISCOVEAY DISCOVERY DESCRIPTION 3Qi ~E ~09 4 II A A 0 9 10 12 13 44 45 46 FOAM OF ACT IVAY CON TENT ALLFASEO OF RELEASE AMOUNT OF ACTIVITY LOCATION OF RELEASE A NA 0 s 10 11 44 45 ec PERSONNEL EXPOSURES 89 11 12 10 PERSONNEL INJUR!ES 89 'l1 12 80 OFFSITE CONSEQUENCES 1+5 LN AA 0 9 LOSS OR DAMAGE TO FACILITY TgPE OCSCAIPTION K~l L~J LN A 09 1G 80 PUBLICliY ig)L09 NA 85 ADDITIONAL FACTORS i I Atteolvaent 89 00 00

Report No.: BFHRO-50-259/771 Report Date: February 14, 1977 Occurrence Date: February 3, 1977 Facility: Browns Ferry Nuclear Plant EVENT DESCRIPTION On February 3, 1977, from 0929 to 1129 hours0.0131 days <br />0.314 hours <br />0.00187 weeks <br />4.295845e-4 months <br />, the reservoir water temp'erature exceeded the maximum temperature rise of 5 degrees F. The maximum value was 6.2 degrees F occurring at 1029 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.915345e-4 months <br />. The maximum downstream temperature was 43 degrees F. (BFHRO-50-259/771)

CAUSE DHSCRIPTION A computer program, which is run daily, calculates for the next 24-hour period hourly values of maximum temperature and temperature rise in the reservoir as a function of scheduled nuclear and hydro plant generation levels and recommends to the Browns Ferry plant operator the most economical combination of condenser cooling at the plant.

Releases from Guntersville and Wheeler Hydro Plants had'een fairly steady from 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> until 2300 hours0.0266 days <br />0.639 hours <br />0.0038 weeks <br />8.7515e-4 months <br /> on February 2 at rates that produced river flows in excess of 20,000 cfs. The hydro discharges were then reduced at 2400 hours0.0278 days <br />0.667 hours <br />0.00397 weeks <br />9.132e-4 months <br /> and held at very low flows until 0500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> on February 3. The computer program was not updated to reflect a change in hydro plant generation or the plant notified of this change. As a result, the river temperature rise exceeded 5 degrees F before appropriate action at Browns Ferry could be taken to avoid it. Water temperature at the time of the streamflow reduction was 40.5 degrees F downstream with an indicated Delta T of 3.3 degrees F.

The Browne Ferry plant condenser cooling operating mode is scheduled in advance by the computer calculation. When the February 3 schedule was developed on February 2, river flows were predicted to be "adequate for condenser cooling at Browns Ferry. However, the Guntersville and Wheeler Hydro Plants were shut down during the night of February 2, resulting in greatly reduced river flows. Browns Ferry personnel were not notified of this situation, so Browns Ferry continued to operate at the predicted load.

The temperature increase was detected by'he downstream monitors after'he river flow was reestablished.

DHSIGNATION OF APPARHNT CAUSH OF OCCURRHNCH River flow was not maintained according to the predicted schedule. When the change was made, Browne Ferry personnel were not notified.

CORRHCTIVH ACTION When the plant superintendent noticed the rapid increase in the river temper-ature rise, he called the assistant chief load dispatcher in Chattanooga to xequest more river flow. He was then informed of the decreased river flow that had occurred a few hours earlier and was advised that river flow had already been increased to a level that should assist in maintaining temperatures less than the 5 degrees F limit. Therefore, plant load was not reduced.

In order to prevent future occurrences of this type, the plant operator will be notified immediately by the load coordinator of significant deviations from the predicted river flow as required by existing procedures. Using this information, the plant operating personnel will select the optimum

C condenser cooling modes to ensure compliance with the technical speci-fications. The importance of following this procedure has been reemphasized to the plant operators and the Power System Load Coordinator.

Table 1 ANALYSIS Ol'IVER VATER TE".PERATURE DATA BEFORE AND POLLOllPilG OCCURRENCE Temperature Guntersville Wheeler Date and Time Dovnstream Delta T Dischar e Discharge CST OP '100 CPS 2/2/77, 1900 Hrs. 443 419 2000 332 303

'2100 322 300 2200 212 272 2300 175 233 2400 112 ill 2/3 /77, 0100 40.5 3.3 26 14 0200 40.3 3.0 0 0 0300 40.3 2.9 0 0 0400 40.2 3.0 90 83 0500 40.3 3.5 214 178 0600 40.7 4.2 214 178 0700 41.0 4.6 442 461 0800 40.8 4' 491 ,586 0829 41.0. 4,4 0900 41.4 4.8 488, 592 0914 41.7 5,0 0929 41.9 5.2 0944 42.. 1 5.4 0959 42.4 5,7 583 1014 42.8 6.0 1029 43,0 6.2 1044 42.9 6.1 1059 42.7 5.9 512 536 1114 42o3 5.4 1129 41.8 4.9 1144 41.3 4, lt 1159 40. 9 4.0 507 1214 40. 5 3' 1229 40.0 3.0