ML20084H894

AO BFAO-7418:on 740318,RCIC Failed to Reach Rated Flow within Required Time After Manual Initiation.Caused by Malfunction of Egm Control Box Due to Low Power Supply Voltage

ML20084H894
Person / Time
Site:	Browns Ferry
Issue date:	03/27/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
AO-BFAO-7418, NUDOCS 8305060110
Download: ML20084H894 (3)

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(") h TENNESSEE VALLEY AUTHO AITY C'"3T5

. CHATTANCOGA, TENNESSEE 374c1

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March 27, 1974 {%g52,e]rj EC '\. -

APA 3 19W 3 h' y Mr. John F. O' Leary, Director i  ?- . .,44  :

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Office of Regulation -

U.S. Atomic Energy Cocaission 6.

Washington, DC 20545 Y 2, l 6 '

Dear 1.'r. O' Leary:

TENNESSEE VALLEY AUTHORITY - BROETS FERRY HUCLEAR PLANT UNIT 1 -

DOCKET HO. 50-259 - FACILITY OPERATING LICENSE DPR ABNORMAL OCCURRENCE REPORT BFAO-7418 The enclosed report is to provide details concerning the reactor core isolation cooling system that failed to reach rated flow within the required 30 seconds after a canual initiation which occurred on Browns Ferry nuclear Plant unit 1 on March 18, 1974, and is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973.

Very truly yours, TEmiESSEE VALLEY AUTHORITY

> I E. F. Thomas Director of Power Production Enclosure CC (Enclosure):

Mr. Norman C. Moseley, Director Region II Regulatory Operations Office, USAEC 230 Peachtree Street, ml., Suite 818 Atlanta, Georgia 30303

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ABNORMAL OCCURRENCE REPORT Report No.: BFAO-7418W Report Date: March 27, 1974 Occurrence Date: March 18, 1974 Facility: Browns Ferry Huclear Plant unit 1 Identification of Occurrence The reactor core isolation cooling system failed to reach rated flow within the required 30 seconds after a manual initiation.

Conditions Prior to Occurrence

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The reactor was operating at approximately 68-percent power.

Description of Occurrence  !

At approximately 2:00 p.m., as part of routine surveillance testing, the RCIC system was manually initiated. The pu=p failed to reach full flow in the required 30 seconds. The pu=p did reach full flow in 31.6 seconds. The RCIC system was then declared inoperable.

Designation of Annarent Cause of Occurrence The slow response to the manual initiation was traced to a malfunction of the MM control box. Investigation revealed that the power supply voltage within the EGM box was too low for proper operation. The power supply to the EGM box was checked and found to be proper. It was then determined that the EGM box was faulty.

Analysis of Occurrence Although the'RCIC failed to reach full flow in the required time, it did reach full flow. If it had been eclled on in an emergency, it would have performed its intended function. The HPCI was demonstrated operable immediately following the occurrence and would have been available if needed.

Corrective Action The EM box was repinced and the new box calibrated. The surveillance test was run and the RCIC reached full flow in 18.2 seconds following a manual initiation, c The RCIC was then declared operable. The faulty EGM box was checked, and the line surge protector on the power supply input was found to have deteriorated to the point where it was adversely affecting the power supply volta 6e. The surge protector was replaced.

Failure Data CRl--Klipvolt Transient Voltage Suppressor, Polarized type, Saskes Tarzian, Part No. S-240.

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O Failure Data (ccntinued) ,

There have been two previous failures of the surge protector, one on RCIC and f the other on liPCI. The previous failure on RCIC was before plant licensing and was reported by Construction forces on DDN-143 dated Ju]y 26, 1973. The surge

protector failure on liPCI was reported in BFI.0-747U on an occurrence dated January 26, 1974 Both these failures were directly attributable to either a short or a ground on the EGM box. The surge protector in this instance had not failed completely but had deteriorated to the point of affecting governor Performance.

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