ML20126E347

Ro:On 660808,after Reactor Trip Due to Lightning,Turbine Generator Did Not Trip & Continued to Carry Facility Power from Residual Steam in Primary Sys,Reducing Reactor Pressure.Caused by Bypass Valve Malfunction

ML20126E347
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	08/09/1966
From:	Haueter R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Boyd R, Doan R US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8101190580
Download: ML20126E347 (2)

Text

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'." PARNALL ROAD OFF! F TVX Sif 787-1985 Nrh h N' D~

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TO - DR. R. L. DOAN

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,. ,, DIRECTOR OF REACTOR LICENS!58._ . 9 6 .

ATTENTION - ROGER S. 90TD w THIS REPORT OF OPERATIONS AT BIG ROCK POINT IS SUBMITTED IN ACCORDANCE WITH SECTION S. D. =1 B. OF LICENSE DPR-6' DOCKET 90-15S' WHICH SPECIFIES' AS IMMEDI ATE REPORT OF ANY ACCIDENTAL RELIASE OF RADIDACTIVITY.

.A TRIP OF THE BIS ROCK POINT REACTOR WAS EXPERIENCED AT 5-01 PM 9W AUGUST S' 1966* DUE TO THE TRIPPING OF THE ISS EV TRANSMISSION

• ' LINE' RESULTING FROM LIGHTNING.. AT THE TIME OF THE TRIP' TME PLANT WAS LOADED TO APPROXIMATELY 40 MWE-SROSS.

ALTHOUGH THE REACTOR TRIPPED DUE TO.MISH REACTOR PRESSURE WPON LOSS OF LOAD' THE TURBINE-SENERATOR DID NOT TRIP AND CONTINUED TO CARRY STATION POWER FROM RESIDUAL STEAM IN THE PRIMARY SYSTEM.

, THE OPERATOR-TRIPPED THE TURBINE-SENERATOR AFTER ABOUT && SECONDS TO PREVENT FURTHER REDUCTION IN REACTOR PRESSURE.- AT THE TIME OF THE TURBINE-GENERATOR TRIPPING

• THE REACTOR PRESSURE WAS ABOUT 96C PSIO. i THE TRIPPING OF THE TURBINE-SENERATOR RESULTED IN A COMPLETE LOSS OF STATION POWER TO TE PLANT. THE EMERGENCY DIESEL SENERATOR

., AUTOMATICALLY STARTED AND RESTORED ESSENTI AL SERVICES. HOWEVER' THE MAIN STEAM BYPASS VALVE UNEXPECTEDLY OPENED UPON THE LOSS OF STATION POWER. T E FLOW OF STEAM INTO THE CONDENSER' DURING THE i TIME THAT THE MATN STEAM ISOLATION VALVE WAS CLOSING *. WAS SUFFICIENT TO PRESSURIZE THE CONDENSER. AND BLOW ONT. OF THE RUPTURE DIAPHRAGMS ON THE TURBINE EXHAUST CASING.' 'I ESSENTI ALLY' .NONE OF THE STEAM ESCAPED FROM THE TURBINE BUILDING  ;

LOUVERS FOR ABOUT S MINUTES' THE ELAPSED TIME UNTIL STATION POWER

[ WAS RESTORED.- NOVEVER' UPON RESTORATION OF NORMAL VENTILATION IN THE TURBINE ROOM AND ASSOCIATED MIXING OF AIR' SOME STEAM WAS VENTED DUT THROUGH THE UPPER LOUVERS' CARRYING WITH IT SOME SMALL AMOUNI 0F RADI0 ACTIVITY. ,

PRIOR 70 REACTOR TRIP' THE OFF-SAS RATE WAS APPROXIMATELY.

26'0D0 MICRP CURIES PER SECOND OF FISSION GASES. FOLLOWING THE REACTOR TRIP AND DURING THE MINUTE THAT STEAM WAS BEING RELEASED T0 h THE TURBINE ROOM' SOME SMALL PERCENT OF THE NORMAL OFF-BAS RELE ASE WAS UNDOUBTEDLY CARRIED INTO THE TURBINE

• AND A SMALL PORTION OF THIS WAS

[ EVENTUALLY RELEASED TO THE ENVIRONS THROUGH THE TURBINE ROOM LOUVERS. -

r' N0 SMEARS OF THE AREA NEAR THE PLANT WERE TAKEN IMMEDIATELY-FOLLOWING THE RELEASE DUE TO TE HEAVY RAINFALL OCCURRING AT THE TIME. LATER SURVEYS SHOWED WOTHING AB0VE BACKGROUND. ALL PERSONNEL '

EXCEPT THOSE IN THE CONTROL ROOM WERE EVACUATED TO THE SCREEN-

', NOUSE OR INFORMATION CENTER AND CECKED PRIOR TO RELEASE. 50 EVIDENCE OF ANY CONTAMIN ATION W AS FOUND. ,

t ,

THE MALFUNCTION OF THE BYPASS VALVE IS UNDER INVESTISATION.

i. TESTING OF THE BYPASS VALVE MAS SHOWN 90 DISCREPANCIES EXCEPT THAT THE

• t L VALVE WILL OPEN WHENEVER POWER IS INTERRUPTED TO THE CONTROL CIRCUITS. ,

SNTIL THIS DIFFICULTY CAN' BE EVALUATED AND CORRECTED' A TEMPORARY RELAY C MAS SEEN ADDED TO THE SYSTEM WHICH WILL AUTOMATICALLT CLOSE THE BYPASS

. VALVE' VIA TE MANUAL OVERRIDE FEATURE' WHENEVER AA XX AC POWER IS LOAST TOT TE CONTRE, SYSTER.

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