ML17252A876

Letter Regarding 12/17/1973 Analysis of the Results of Periodic Tests and Calibration Checks Relating to Pressurizer Level Indicated a Setpoint Drift - Indian Point Unit 2

ML17252A876
Person / Time
Site:	Indian Point
Issue date:	12/28/1973
From:	Cobean W Con Edison, Consolidated Edison Co of New York
To:	O'Leary J US Atomic Energy Commission (AEC)
References
Download: ML17252A876 (2)

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50-247 Consolidated Edison Company of New York, Inc ..

4 Irving Place,. New York, NY 10003 Re: Indian Point Unit No. 2 Facility Operating License DPR-26, A0-3-2-17 DOCKETED USAEC On December 17 ,* 1973, an analysis of the results of periodic tests and calibration checks relating to pressurizer level indi-cated that the* setting for one of the three bistables associated with high pressurizer level reactor trip was slig.htly above that required by Technical Specification 2.3.1.c(l)*. At the time of these periodic tests and calibration checks, the reactor was in the cold shutdown condition for maintenance work associated with repairs. to the feedwater piping for No. 22 steam generator.

The particular bistable device is part of a two out of three logic system which provides for a reactor trip signal for high pressurizer level. The setpoint was found to be at 92.25% of span instead of the < 92% of the span required b~ the Technical Specifications. The-channel associated with this device was recalibrated and retested satisfactorily.

Because this trip circuitry is a two out of three logic and since both of the other two bistables of this system were found to be operating corre.ctly-, it can be assumed th-at a* high leVel* :.,~*

in the pressurizer would have tripped the reactor within the prescribed limits.

The recent number of setpoint drift occurrences has prompted us to investigate this matter. Our Engineering Department, in conjunction with site personnel, is reviewing power and ground circuitry.in order to evaluate the sensitivity of the bistable setpoint to possible transients from these (ground and power) circuits. In addition, the manufacturer is also being consulted*

about this matter. '**

Mr.* John F. O'Leary *December 28, 1973 Because the logic circuitry was still operating, we feel that safety implications to the occurrence are slight. However, the investigations into the reasons for setpoint drift will con-tinue with the intent of reducing the likelihood of their inci-dence.

Very truly yours, w~ Q__G,JoP:iM/,

Warren R. Cobean, Jr.

Manager - Nuclear Power Generation Department cc/ Mr. James P. O'Reilly