ML19305B866

Discusses Review of Sys Which Might Have Valve Configurations Leading to Event 5 Accidents.Low Pressure Safety Injection Sys Has Configuration in Question.Lists Steps to Be Taken to Decrease Probability of Event 5

ML19305B866
Person / Time
Site:	Maine Yankee
Issue date:	03/13/1980
From:	Johnson W Maine Yankee
To:	Office of Nuclear Reactor Regulation
References
WMY-80-49, NUDOCS 8003200502
Download: ML19305B866 (2)

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IMS B.3.2.1 KMY 80-49 March 13,1980 United States Nuclear Regulatory Commission Washington, DC 20555 Attention: Of fice of Nuclear Reactor Regulation

References:

(1 ) License No. DPR-36 (Docket No. 50-309)

(2) USNRC Letter to All LWR Licensees dated February 23, 1980

Subject:

LWR Primary Coolant System Pressure Isolation Valves

Dear Sir:

Reference (2) requested that Maine Yankee review the Low Pressure Safety Injection System and any other system which might have a valve configuration which coul d l ead to an Event V accident. The valve configurations which might lead to this event are two check valves in series, or two check valves in series with a motor operated valve. Maine Yankee has completed a review of pertinent systems and concludes that the Low Pressure Safety Injection System has the configuration in question.

This system consists of two Safety Class I check valves in series with a Safety Class 2 motor operated valve which is normall y closed. This valve opens on a Safety Injection Actuation Signal and is cycl ed quarterly to demonstrate operability.

Continuous surveillance and periodic tests are not presently performed to ensu:a integrity. Maine Yankee is not aware of check valves which have been known, or found, to lack integrity.

Past history does indicate that the hard seated check valve closest to the reactor coolant system has had slight leakage in the past.

To decrease the probability of an Event V occurrence, Maine Yankee will initiate the following steps during the next scheduled maintenance outage:

1)

Local pressure indicators will be installed between the 2nd check val ve and the normall y closed motor operated valve.

2)

Procedural changes will be made to ensure that the operators check the pressure indicators before the motor operated valve is cycled for their operability checks.

8008200 [ O

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United Stctes Nuclear R2gulatory Commission Mrrch 13,1980 Offica of Nuclear Ratetor Regulation Page 2 s

The above steps will significantly reduce the probability of an Event V accident occurrence to well below that postulated in the Wash-1400 Reactor Safety Study and further action is not anticipated.

We trust that this information is acceptable to you; however, should you have any questions, please contact us.

Very trul y yours, MAINE YANKEE ATOMIC POWER COMPANY W. P Johnson Vice President PAR /ncj COMMONWEALTH OF MASSACHUSETTS)

)sS COUNTY OF WORCESTER

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Then personally appeared before me, W. P. Johnson, who, being duly sworn, did state that he is a Vice President of Maine Yankee Atomic Power Company *,

that he is duly authorized to execute and file the foregoing request in the name and on the behal f of Maine Yankee Atomic Power Company, and that the statements therein are true to the best of his knowledge and belief.

Robert H. Groce Notary Publ ic

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My Commission Expires September 14, 1984

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