ML20084A232

AO 3-2-17:on 731217,one Bistable Setting Exceeded Tech Spec Limit of 92%.Cause of Setpoint Drift Under Investigation. Channel Recalibr

ML20084A232
Person / Time
Site:	Indian Point
Issue date:	12/28/1973
From:	Cobean W CONSOLIDATED EDISON CO. OF NEW YORK, INC.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084A234	List: ML20084A232 ML20084A252
References
AO-3-2-17, NUDOCS 8304050136
Download: ML20084A232 (2)

Text

y o

o 4

50-247 A_.,

'j 1 Consolidated Edison Company of New York. Inc.

. 2...., % ; ti 4 Irving Place, New York, N Y 10003 December 28, 1973 Re:

Indian Point Unit No. 2 Facility Operating License DPR-26, AO-3-2-17 N

Y rf f f,1

\\

Mr. John F. O' Leary, Director :

fQ Q '-

Directorate of Licensing p;l M Jgg F.

j.

Office of Regulation Washington, D. C.

20545 9

' tt/ m u*

f l6

• ,- '.e/y l% %.

j' f4 Dear Mr. O' Leary

'l y ~ ; 7

.-.s The following report is provided pursuant to the require-ments of Section 6.12.2 (a) of the Technical Specifications to Facility Operating License No. DPR-26.

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 slightly above that required by Technical Specification 2.3.1.c (1).

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 by the Technical

~

Specifications.

The channel associated with this device was recalibrated and retested satisfactorily.

1 1

8 0-meo Because this trip circuitry is a two out of three logic and since both of the other two bistables of this system were found l

58 to be operating correctly, it can be assumed that a high level l

bg in the pressurizer would have tripped the reactor within the e

prescribed limits.

3d oc mo -

The recent number of setpoint drift occurrences has prompted D

us to investigate this matter.

Our Engineering Department, in l

conjunction with site personnel, is reviewing power and ground mam 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 beingkcionsulted l

COPY SENT REGION Va 4gfI

about this matter.

/

n aY d5 t._

... ~..

O.

n sj Mr. John F. O' Leary Dece er 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, h

Warren R. Cobean, Jr.

Manager - Nuclear Power Generation Department cc/

Mr. James P. O'Reilly l

l 4