ML20086L118

Ao:On 731224,unexplained Trips of RCIC Turbine During Startup Testing Reported.Caused by Improper Adjustment of Mechanical Linkage Between Trip Valve & Overspeed Trip Mechanism.Linkage Readjusted

ML20086L118
Person / Time
Site:	Peach Bottom
Issue date:	01/02/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086L121	List: ML20086L118 ML20086L123
References
NUDOCS 8402070404
Download: ML20086L118 (2)

Text

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PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET PHILADELPHIA. PA.19101 (21518414ooO January 2, 1974 Mr. A. Giambusso Deputy Director of Reae:or Projects j , .4p

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United States Atomic Energy Commission f Directorate of Licensing Washington, D. C.

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Dear Mr. Giambusso ,

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Reference:

Peach Bottom Atomic Power Station - Unit 2 '

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Facility Operating License DPR-44 Y O Docket No. 50-277 (('?- Aj,

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Subject:

Abnormal Occurrence  %

On December 24, 1973, the unexplained tripping of the RCIC turbine during startup testing was reported to Mr. Paul Nelson, A.E.C. Region I, Regulatory Operations Office.

In accordance with Section 6.7.2.A of the Technical Specifications, Appandix A of DPR-44 for Unit //2 Peach Bottom Atomic Power Station, this trip-ping is being reported to the Directorate of Licensing as an Abnormal Occurrence.

RCIC Turbine Trip Early on December 24, 1973, with the reactor at approximately 15% power, the RCIC turbine was operated cn several occasions to support startup testing of the RCIC System. On three different occasions the turbine tripped for no apparent reason. No turbine trip signals were annunciated prior to each trip. and folinwing each trip, the turoine was reset from the control room and restarted. For these reasons, initial investigation was directed toward the mechanical. linkage between the mechanical overspeed trip mechanism and the turbine trip valve. Following the successful completion of the RCIC startup test the reactor was shutdown to permit work associated with the main turbine generator to proceed.

Investigation anLCorrective Action Further investigation following shutdown of the reactor indicated that the cause of the turbine trip was an improper adjustment of.the mechanical link-age between the trip valve and the overspeed trip mechanism. Improper adjustment j,/

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!/f1'bq PDR ADDCK 05000277 REGULATORY OPERATIONS l 8 PDR FILE COPY 5

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,e m m placed the trip valve in a partially latched position such that normal turbine vibration could cause the valve to trip closed. The turbine hydraulic and mechanical linkage was inspected by the turbine manuf acturer's representative and readjusted. Static trip tests were perf ormed on the turbine by the manu-facturer's representative. As left, the turbine trip valve is fully latched and both the mechanical and electrical trip mechanisms are operating as designed.

Additional testing on the electrical overspeed trip shall be performed prior to returing the primary system to ) 100 psig. Dynamic tests will be performed during the next reactor startup.

Safety Implications As described above, the tripping of the RCIC turbine occurred during the period of time that the RCIC system was being tested for its time response during a vessel injection test at full reactor pressure. These start-up tests were successfully completed. The HPCI turbine was fully operational during this time interval. In accordance with the testing schedule, the reactor was scrammed from the 15% power level shortly af ter completing a successful RCIC vessel injection test. Reactor pressure was subsequently reduced to zero and the reactor vessel vented. Since the HPCI was operabic during the period of time the reactor pressure was above 100 psig and .he RCIC was operable and successfully used to complete the vessel injection test, adequate high pressure emergency core cooling systems were available during reactor power operation.

The RCIC was considered operable during this period since the inadvertent trips could be reset quickly from the control room and the turbir,e restarted. Therefore, no safety implications are associated with this occurrence.

Very truly yours, j / Y ,(A u M. J. Cooney, A s' t Gen' t Supt.

Gederation Division MJC:kam cc: Mr. J. P. O'Reilly Director, Region i United States Atomic Energy Conmission 631 Park Avenue King of Prussia, Pa. 19406 I

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