ML20086L151

Telecopy AO 74-23:on 740427,HPCI Turbine Isolated During Reactor Vessel Injection Start Up Test.Caused by Faster Stop Valve Opening Speed.Isolation Logic Reset

ML20086L151
Person / Time
Site:	Peach Bottom
Issue date:	04/29/1974
From:	Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086L146	List: ML20086L143 ML20086L151
References
AO-74-23, NUDOCS 8402070419
Download: ML20086L151 (2)

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. [t*k-I April 29, 1974 UQ Nr. James P. O'Reilly, Director United States Atomic Energy Co: mission Directorate of Reguhtory Operations 631 Park Avenue King of Prussia, Pennsylvania 19406

Subject:

Abnor-al Occurrence 24-Hour Notification Confir=ing cy conversation with Mr. R.A. Feil, A.E.C. Region I Regulatory Operations Office on April 28, 1974.

Reference:

License Number DPR 44, Anendment Number 1 Technical Specification 3 5.C.1 Report No.: 50-277-74-23 .

Report Date: April 29, 1974 Occurrence Date: April 27, 1974

' Facility: Peach Bottom Atomic Power Station R.D. 1, Delta, Pennsylvania 17314 Identification of Occurrence:

HPCI Turbine isolated during a reactor vessel injection start-up test.

Conditions Prior to Occurrence:

Plant operating at approxicately 50% power for the purpose of perfoming start-up testing.

Designation of' Occurrence:

As part of the start-up test program, and as a follow-up to a HPCI system isolation which occurred on April 16, 1974, HPCI cold -

' quick start vessel injection testing was being performed. Reactor power l was at approxicately 50% in stesdy state operation. Following the cold quick start initiation, an HPCI Turbine isointion occurred. This isolation was caused by a high steam flow condition which is sensed by differential pressure switches connected to an elbow tap flow element

! . in the steam supply line to the HPCI Turbine. Following the isolation, additional quick starts on the HPCI were perforced' to demonstrate that the system was operable both on the test loop and for injecting to the reactor vessel. This was proven by actually delivering '

rated flow to the vessel following the initial isolation.

Designation of Apparent Cause of Occurrence:

Observation of the HPCI Turbine stop valve during the initial cold quick start appears to indicate that the stop valve opening speed was significantly faster during this startup than has been observed on a hot startup. No quantitative data as to opening speed of this valve was obtained during this quick start since this para =eter was not instru=ented at that tiee. At the present time it is believed that too rapid an opening stroke on the HPCI hydraulic stop valve could cause a high steam flow condition and correctly cause the high steam flo isolation to occur.

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Analycio of Occugco;

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Th2 initid, itWafien df the HFCI system durinho cold quick ctort v;; eel injection tcat has no safety icplications in that the cyst:.m

van demonstrated ic=ediately following this isolation to be capable i

! of injecting water to the reactor vessel. This icolation could I conceivably incredse the time from actuation until full rated flow to the vessel is achieved by the abort period of time to reset the isolation cignal. This delay is not considered significant at the power levels achieved during the startup program to date. Startup testing is perforced for the purpose of identifying and correcting minor control problems with engineered safeguard syste=s prior to achieving reactor power levels where design system resw nse is required to citigate accidents.

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Corrective Action:

Following the initial isolation, the isolation logic was reset.

Additional HICI quick starts were performed using the test flow loop. Adjusteents were c:ade to the steam flow orifices in the Turbine stop valve in an attempt to reduce the operating speed of this valve.

Test results indicated that some reduction in valve speed was obtained with the valve in a hot condition. No determination of valve speed in the cold condition could be verified since it takes app:oxicately 2f+ hours for the netal associated with the valve to cool to ambient conditions. Following these adjusteento, vessel injection tests were

, successfully accomplished. Sc=e adjustment of controls is votill required to obtain optic:u= system performnce.

As part of the above investigation, a transducer has been inctalled on the HPCI hydraulie stop valve. This transducer censuresvalve cotion as a function of time. Additional tests are planned from the cold condition to determine the exact cauce of the isolation and operating time of the turbine stop valve as a function of te=perature. These tests cust be spaced at:least 2f+-hou:s apart - to permit the equipment to reach ambient conditions between tests. When successful cold quick starts on the test loop have been obtained, the cold quick start vessel injection test shall be repeated.

Failure Data:

. A previcus HPCI system isolation was reported as Abnormal Occurrence

.50-277-7f+-22.

WMJ W. T. Ullrich, Superintendent Peach Botto= Atomic Power Station 9