ML20085G227
| ML20085G227 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 02/10/1975 |
| From: | Eric Thomas TENNESSEE VALLEY AUTHORITY |
| To: | Case E Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8308240701 | |
| Download: ML20085G227 (2) | |
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V TENNESSEE VALLEY AUTHORITY
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CHATTANOOGA. TENNESSEE 374ol
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Mr. Edson G. Case
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Acting Director of Licensing bl,/.
U.S. Nuclear Regulatory Co::rission N ~ 83 Washington, DC 20545
Dear Mr. Case:
TENNESSES VALLEY AUTHORITY - BROWS FERRY NUCLEAR PLANT UNIT 1 -
DOCIET NO. 50-259 - FACILITY OPERATHiG LICENSE DPR ABNORMAL OCCURREiCEREPORTBFAO-50-259/751W The enclosed report is to provide details concerning improper time setting of R.'IRSW pu=p D1 start sequence time delay relay TDl-D and is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973. This event occurred on Browns Ferr/
Nuclear Plant units 1 and 2 on January 31, 1975.
Very truly yours, TEIUiESSEE VALLEY AUTHORITY IhW a E. F. Thomas Director of Power Production Enclosure CC (Enclosure):
Mr. Nor=n1 C. Poseley, Director U.S. Iiuclear Regulatory Cor::ission Regional Office 230 Peachtree Street, Ird., Suite 818 Atlanta, Georgia 30303 gs F
1874 8308240701 750210 PDR ADOCK 05000259 S
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ABNORMAL OCCURRE:!CE REFORT Report No.: BFAO-50-259/751W Report Date: February 10, 1975 Occurrence Date: January 31, 1975 Facility: Browns Ferry Huclear Plant units 1 and 2 Identification of Occurrence I= proper time setting of RERSW pu=p D1 start sequence time delay relay TD1-D.
Conditions Prior to Occurrence Unit 1 was operating at rated power and unit 2 at approximately 700 We.
Descrintien of Occurrence At 1330 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.06065e-4 months <br /> durirq a routine surveillance test, RHRSU pump D1 start sequence time delcy relcy TDl-D actuated in 6.14 seconds instead of the 13 to 15 seconds required.
Designation of Antarent Cause of Occurrence The tire dial setting on reley TDl-D was found to be 6 seconds. The data sheets of the previous surveillance which was performed August 14,197h, recorded the "as-left" setting of relay TD1-D as 13.71 seconds. The timer dial setting had apparently been =oved inadvertent 2y since the previous surveillance test.
Analysis or Occurrence The short time cetting of relay TDl-D would have altered the designed starting l
sequence of crercenc'/ core cooling punps on diesel generator "D" power due to Emergency Equipment Cooling Water pump D1 starting approximately 8 seconds early. Precperational testing has proven that single tirer failures in the pu=p starting sequence logic for diesel generator power causes no detrimental overloading of diesel generators. This occurrence caused no danage to any systems, structures, or cocoonents, There vera no adverse effects to the health and safety of the public, and there were no personnel injuries or exposures due to this occu-rence.
Corrective Action s
Relay TD1-D was recalibrated and left with an operating time of 14.12 seconds.
The surveillance instruction on the subject timer and other s%mr timers will-be changed to call for "as-found" and "as-left" relay dial knob settings in addition to "as-found" and "as-left" relay operation times.
Failure Data None e3
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