ML20084H496

AO BFAO-7442W:on 740621,reactor Scrammed by Low Condenser Vacuum Due to Steam Jet Air Ejector Malfunction.Hpci Sys Failed to Initiate Manually.Caused by Foreign Particles in Oil Sys Contributing to Pilot Valve Seating Failure

ML20084H496
Person / Time
Site:	Browns Ferry
Issue date:	07/01/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084H498	List: ML20084H496 ML20084H499
References
AO-BFAO-7442W, NUDOCS 8305040351
Download: ML20084H496 (3)

Text

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V % s+' a lir. ' John F. O' Leary, Director G 0,-

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Office of Regulation U.S. Atomic Energy Cornission

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~Uashington, DC 205b5 Dear _ Fir. C' Leary'  ;

TZuiESSEE VALLYi AUTHORITY - BRO'US FERRY ITUCLEAR PLilIT UUIT 1 -

DOCI ET 110.-50-259 - SACILITY OPERATIUG LICII!SE DPR ABHORI'AL OCCURIE CE REPORT BM.0-7%2W  !

t The enclosed report is 'to provide details concerning HPCI turbine Vnich failed t, start nanually end reach operatirg; spcod and is cubnitted in acecrd:nce u.:.th Lppendix A to Regulctory Guide 1.16, .

Revision 1, October 1973. -This event occurred on Browns Ferry Huclear ,

Plant unit'l on June 21,-1974.  ;

Very truly-yours, i

TEUNESSEE VALIZY AUTHORITY ,

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E. F.-Thomas

' Director of Forer Production Enciosure a CC (Enclosure): _

L'r. Ilornnn C. Ibseley, Director Region II Regulatory Operations Office, USAEC

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. b' b Report'Iio. : BFAO-7442W Report Date: July 1, 1974 Occurrence Date: June 21, 1974 Facility: Browns Ferry nuclear Plant unit 1 I

Identification of Occurrence HPCI tufoinc failed to start manually and reach operating speed.

Conditions Prior to Occurrence Before the occurrence, the unit was operating at rated pressure and temperature on a 300-hour narranty demonstration run at 100-percent pouer.

Description of Occurrence The reactor scranmed at 9: % n n., June 21, 1974, by lou condenser vacuun because of a steen jet air ejector nalfanction. The HPCI systen was initiated nanual]y to be available if required to centrol vessel uator level, pressure, and tennerature.

Severcl nenucl-starts were attenated before the HFCI turbine started. The ITCI was declared inoperable, end the required surveillance on other CSSC systens was conducted while the reactor was in the shutdown todo. ~

' Designation of Atuarent Cause of Occurrence During cach manual start attempt, it uas observed that the turbine step valve did not fully open and the turbine failed to reach operating speed. hne.n the stop valve did cp .n ft:11y. the unit cyrAf eS n designed.

A study of the turbine stop valve assembly indicated that, during the start attenpts, the pilot valve was not scating correct.17 or the operating oil pressure was lov. Im inspection of the oil systen revealed the presence of. foreign materials. These particles probably contributed to the pilot valve fai'ure to

• seat correctly. Subsecuent inspection also revealed i= proper pilot valve seating contact.

Analysis of Occurrence During the period of time that the HPCI turbine vould not start, all rcraining safety systens ucre available, vessel water level was controlled at all times by ot.hcr systems, and there were no adverse consequences experienced.

' Corrective Action The turbina stop valve pilot piston was rcroved and disasserbled. A contact check uns nade between the pisten end its seat which revealed improper setting contact. The pilot seat was lapped and the pisten uas =achined to fit. A leak check uns performed, and the results ucre satisfactory. _The pilot piston .

ring chanber was honed and polished to reduce sliding friction.

The turbine oil reservoir uns drained and oil acrples vere checked for particulates. Sene very snall particles were fcund. . The oil reservoir was thorouchly . clerned. The pump cear reducer reservoir was opened and cleaned.

Oil drain piping was recoved and inspected. Pust blisters were found in accc drain piping cnd were renoved. Huncrous small lubrication and control oil

p . p U V CorrectiveAction(continued) .

pipes vere renoved end incpected for cleanlinocc. A te=porary filter vac installed in the oil circuit and the oil s/ sten van fluched using ncy clean oil. The oil was fluched until the .termorar/ filtern indicated no dirt was being picked up. Fluching duration vac approximately 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br />. Idl orifices in the oil lubrication cycten vare incpected to ensure that they were free of foreign matericl. The turbine thract and . journal bearings were inspected and found $n good condition. The oil piping unc returned to its normal configuration, and new filtered oil wac instelled. The auxiliar/ oil pug was started, and cll preccurca vere found to be caticfactory. The turbine stop velve was stroked nine times and operated satisfactorily on all actuntions.

The HFCI unit vac ctarted three titec using auxilirry boiler stem. The unit perforned catisfactorily cach tino. Startup speedc and stop valve actuation inre nor dl.. The EPCI was declared operable on June 28, 1974, at 2:10 a.m.

Failure Data The velve is a Schutte end Koerting Compay inverted oil operated stop velve.

A previouc. failure of thic nature was reported in Abnoncal Occurrence Report BF/O-7439W dated June 19, 1974.

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