ML17252A898

Letter Informing of 06/07/1973 Occurrence of Flow Trip Settings Below Technical Specifications While Performing Periodic Tests and Calibration Checks Relating to Reactor Coolant Flow - Indian Point Unit 2

ML17252A898
Person / Time
Site:	Indian Point
Issue date:	06/15/1973
From:	Caldwell W Consolidated Edison Co of New York
To:	O'Leary J US Atomic Energy Commission (AEC)
References
Download: ML17252A898 (2)

Text

.,.-\* -**-- *.William E. Caldwel *

\L '*~f.... Vice President Fifa Cy..,

Consolidated Edison Company of New York. Inc.

4 Irving Place. New York. N Y 10003 T~lephone (212) 460-5181 June 15, 1973 Indian Point Unit No. 2 AEC Docket No. 50-247 Facility Operating License DPR-26 Mr. John P. O'Leary.

Directorate of Licensin~~--

u. S. Atdmic Ertergy Commission Washington, *o. c. 20~45 Dear Mr. O'Leary The following report of Abnormal Occurrence No. 3-2-8 is*provided pursuant to the requirements of Section 6.6.l.B_of the Technical Specifications to Facility Operating License No. DPR-26.

On June 7, 1~73, while performing periodic tests and calibration checks relating to reactor coolant flow, l t was determined that the flow trip settings were below those required by Technical Specification 2.3.1.B-(6). At the time of occurrence, the reactor was critical at zero power for zero power physics testing.

The discrepancy is* believed to have resulted from an improper initial calibration, or possibly, instrument drift. To correct the si.tu~tion, the instruments were reset so that their outputs would in.itiate a trip at the reactor coO'lant flow condition prescribed by these setpoints in the T~chnica.i Specifications.

During future calibration checksi particular attention will be paid to these instruments to enable a more definitive deter-mination as to the cause of the problem.

Safety implications relating to this occurrence are considered to be slight. The discrepancies in the flow instrument outputs were detected during a routi,ne surveillance test which is performed monthly. Furthermore, .there are two additional, trip circuits providing react6r p~otection againit a loss of c~olant flow incident. Even if two of the three flow instrun,tents in a particular. coolant loop failed to detect a low coolant .flow in that loop, a signal from the pump circuit breaker opening or from low voltage or low frequency on the pump power supply bus would also trip the plant. It should also be noted that 3328

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• b *.J Mr. John P. O'Leary Atomic Energy Commission

-2~ June 15,.1973 Re Indian Point Unit No. 2 AEC Docket No. 50-:-247 1.

Facility Operating License DPR-26

• the low coolant flow trip.circuitry only serves to pr~tect the reactor in the event that one' or two reactor coolant p'umps become inoperative while the reactor is operating at or near rated power.** Operation of the reactor up until the time the discrepancy was noted had not involved power levels in excess of 5% of the rated value. Finally,.nohe of the setpoints were found* to be set below 87% of full reactor coolant flow~* In tpe accident analysis discussed in the Final Safety Anaiysis Report, it was assumed that the trip signal was initiated at 87%. Hence, the related safety implications to this occurrence are slight.

rakas*

md ant Vice President