ML20085M046

AO BFAO-747W:on 730126,during Startup Testing,Failure of HPCI Sys to Pump to Vessel Experienced.Caused by High Gain Setting on Flow Controller.Gain of Flow Controller Decreased.Defective Components Replaced

ML20085M046
Person / Time
Site:	Browns Ferry
Issue date:	02/05/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085M052	List: ML20085M046 ML20085M053
References
AO-BFAO-747W, NUDOCS 8311070107
Download: ML20085M046 (3)

Text

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TENNEk3SEE VALL AUTHORITY r~1J) 17 f CHATTANQQGA, TENNESSEE, avaa d .1/c_

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Mr. John F. O' Leary, Director '\ L- F Directorate of Licensing \EQQqT'N .

Office of Regulation U.S. Atomic Energy Ccenission Washington, DC 20545

Dear Mr. O' Leary:

TEIniESSEE VALIEY AUTHORITY - BROWNS FERRY NUCIEAR PIAliT UNIT 1 -

DOCKET NO. 50-259 - FACILITY OIEPATHIG LICENSE DPR ABNOR'&L OCCURREHCE REPORT BFAO-7474 The enclosed report is to provide details concerning the F2CI failure to pump to the vessel, which cecurred on Browns Ferry Nuclear Plant unit 1 on January 26, 1974, and is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973.

Very truly yours, TEICIESSEE VALIEY AUTHORITY

. hilJA E. F. Thomas Director of Power Production Enclosure

, CC(Enclosure):

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

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ABNORMAL OCCURRE: ICE REPORT Report No.: BFAO-7474 Report Date: February 5,1974 Occurrence Date: Januar/ 26, 1973 Facility: Browns Ferry nuclear Plant unit 1 Identification of Occurrence HPCI failure to pu=p to vessel.

Condition Prior to Occurrenec The reactor was operatirs at apprcxi=stely 43-percent thor =al power during startup testing.

Description of Occurrence At approximately 7:15 p.m., the HPCI system was initiated to pu=p to the vessel as required by Startup Test Instruction No. 15. The pump flow and turbine speed were very unstable and the test was aborted. During initiation, arcing was observed coming frc= the limit suitch housing of cotor-operated valve FCV 73-16, HPCI Steam Supply Velve to ?arbine, although the valve operated as required.

The cotor fault was repaired, and a pu:p operability and flow rate test was initiated. The pung flow went to 6,000 spm, but no indication of speed was received in the control ro =. The operator 4 ediately tripped the turbine.

Repairs were made to the EGM governor control box to restore the speed indication. Surveillance testing was initiated with satisfactory results, and HPCI was declared operable. At approxi=ately 3:15 p.m. on January 28, a.

, HPCI vessel injection was initiated. The response was the same as the first l vessel injection on Januar/ 26.

[ . Designation of Atmarent Cause of Occurrence

! The instability- during vessel injection was a result of a high gain sett$ng on l the flow controller M 47 the turbine response too sensitive.

The arcing observed coming from the limit switch housing of the steam supply j valve, FCV 73-16, was caused by a motor lead going to ground.

The loss of speed indication and governor response .during surveillance testing after repair of the valve was a result of defective co=ponents, P21 and CR1, l inside the EGM governor control box. This was caused by the signal to the EGM control box being shorted by transient recorder leads installed during the interim between the first vessel injection. test and the first surveillance test.

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- alysis of Occurrence This test =arked the first time the ITCI had pumped to the pressurized reactor.

It was necessar/ to desensitize the turbine control to achieve pu=p stability.

Although actual flow was not measured during the aborted tests, water was delivered to the reactor vessel; and it is probable that, if called upon in an accident condition, the ITCI would have performed its intended function. In any case, the other safeguard systems were de=onstrated operable immediately following the occurrence end would have been available if needed.

Corrective Action The instability was corrected by decressing the gain of the flow controller.

The vessel injection for STI-15 was then perfomed with satisfactory results.

The motor leads were re-spliced and tape?., the 14 it switch housing cleaned, and the cover repaired. The valve operated satisfactorily during subsequent surveillere.e testing.

The defective corponents in the EM governor control box were replaced and the shorted test leads removed. The governor perfomed satisfactor13y during subsequent surveillance testing.

Failure Data:

The EM governor control box, part number 8070-811, is manufactured by Woodward Governor Corporation. Co=ponents replaced were as follows. y

1. R21: Resistor, Dale, RH-25, 25 watt, 10 ohm, 3 percent 2 CRl: Klipvolt Transient Voltage Suppressor, Polarized typa, Sarkes Tarzian, part number S-240

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