ML17252A895

Letter Reporting a 05/18/1973 Occurrence of a Pressure Transient within the Reactor Coolant System Due to the Closure of Certain Air Operated Valves in the Reactor Coolant Letdown System - Indian Point Unit 2

ML17252A895
Person / Time
Site:	Indian Point
Issue date:	05/25/1979
From:	Caldwell W Consolidated Edison Co of New York
To:	O'Leary J US Atomic Energy Commission (AEC)
References
3-2-5
Download: ML17252A895 (2)

Text

William E. Caldwe.r.

Vice~~sident

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Consolidated Edison Company of New York. Inc.

4 Irving Place, New York. N Y 10003

-Telephone (212) 460-5181 May 25, Re*: -Indian Point Unit No. 2 FacLlity Operating License DPR-26 Mr. John F. O'Leary, Director 50-247 Directorate of Licensing U.S Atomic Energy Commission Washington, D. C. 20545

Dear Mr. O'Leary:

The following report of Abnormal Occurrence No. 3-2-5 is provided*pursuant to the requirements of Section 6.6.1 of the Technical Specifications to Facility Operating License No. DPR-26 ..

On Friday, May 18~ 1973, the Reactor Coolant System was in the process of being heated up in order to ;conduct a hydrostatic te'st. At the time, four :.reactor coolant pumps were in service with Reactor Coolant_ System con-ditions of approximately 440 psig, 1300F, -1980 ppm boron and all control rods inserted. The reactor had not yet been brought to ini tia-1 criticality.

At 0552 hours0.00639 days <br />0.153 hours <br />9.126984e-4 weeks <br />2.10036e-4 months <br />, a pressure transient within the Reactor Coolant System was experienced due to the closure of certain air operated valves in the reactor coolant letdown sys.tern. The reactor coolant pumps and charging

.pump were shutdown _:to:pf.ev~nt any further pressure in-

--creases. Closure of the valves resulted i.n Reactor Coolant System pre~sure increasing to approximately 575 psig. An investigation. revealed that moisture in \

J an air supply line at the refrigerant dryer of the Instrument Air system had frozen. The alternate dryer was placed in service with subsequent*re-establishment

.of the proper pressure-within the Instrument Air System.

Reactor Coolant Syste~ pressure was then. returned to normal.

DOCKETED USA EC

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\ lft Mr.J0hn F. O'Leary May 25, 1973 Investigation as to the cause of the freeze-up disclosed that the suction service* valve to the refrigerant com-

~<=*=-cc- - ~presser had .neen.backseated to eliminate *gland* leaka*ge.

Backseating of this valve, however, als.o resulted in isolation of the low suction pressure shutoff controller for the compressor and this caused .it to remain in ser-v*ice allowing moisture in the air line to *~reeze, and eventually *interrupt the air supply:.

To prevent recurrence, a relo6ation of the suction*pres-sure controller tap to a -point directly on*the suction

.of the compressor is to be accomplished. This will allow backseating of the valve to prevent 'freon leakage along the valv~. stem, without affecting the. control. syst~m . .In the interim, signs have be~n*installed at the dryers prohibiting full-backseating of the subject va*lves while the compressor is in service-.

The sa*fety implications of this occurrence are not con-

• sidered significant.* There was no damage inc:;_urred to any system* or component nor wa*s there any* reason to e,x:-

~ect .any as a result of a pressure transient of this magnitude-. The pressure limitation of 500 psig, at-coolant temperatures less than 220°F, .is imposed only as a means for* providing additional conservati'sin in the application.of fracture*toughness co:r:icepts. The limit also includes the effects of fast neutron .exposure*

which would occur over a two year period of operation.

In light *of the above, it is considered that the safety of the faci.li ty was riot *comprised by this occur.re:q.ce.

.. Very' truly yours,

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cc '."" Mr. Jaine~ *:P ~ o' Rei).iy.,

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