ML20151U197

Informs That Steam Void Formation & Subsequent Water Hammer Effects During Sys Startup Will Not Occur in ECCS as Result of Reactor Coolant Leakage Into Sys,Per Concerns Raised by NRC

ML20151U197
Person / Time
Site:	Quad Cities
Issue date:	04/19/1988
From:	Johnson I COMMONWEALTH EDISON CO.
To:	Murley T Office of Nuclear Reactor Regulation
References
4501K, NUDOCS 8804290297
Download: ML20151U197 (2)

Text

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a i Commonwealth Edison j o []/ One First National Plaza CNcago, Ininois

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\ C 7 Address Reply to: Post Omce Box 767 y \v/ CNcago,luinois 80690 0767  ;

l April 19, 1988 Mr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Quad Cities Station Units 1 and 2 Discharge Pipe Pressure for Core and containment System Tech Spec 3.5.G.2 ,

NRC Docket Nos. 50-254 and 50-265 References (a): Letter from M.S. Turbak to T.E. Murley dated October 6, 1987.

(b): Letter from G. Hallahan to L.D. Butterfield dated October 6, 1987.

(c): Letter from I.M. Johnson to T.E. Murley dated November 24, 1987.

(d): Letter from T. Ross to L.D. Butterfield dated February 3, 1988.

(e): Letter from I.M. Johnson to T.E. Murley dated October 9, 1987. r

Dear Mr. Murley:

The purpose of thit letter is to resolve concerns raised by your staff regarding the potential for water hammer effects in the Emergency Core Cooling Systems (ECCS) at Quad Cities Nuclear Power Station due to the leakage of high pressure reactor coolant into the systems leading to the formation of vapor pockets. In Refenence (a), Commonwealth Edison requested a Technical Specification change pertaining to the manner in which the discharge pipe pressure is measured. By Reference (b), your staff granted a wiiver of  ;

compliance for the Technical Specification 3.5.0.2 while the matter was under t review. Reference (c) supplemented our Technical Specification amendment request by increasing the surveillance requirements of the affected systems.

Your staff reviewed and approved the amendment request via Reference (d), i 4

8804290297 880419 / 0 PDR ADOCK 05000254 P PDR

A T.E. Murley April 19, 1988 Lastly, in Reference (e), Commonwealth Edison agreed to review concerns raised by your staff regarding postulated water hanumer effects in ECCS systems. This issue was first raised at Duane Arnold.

We have completed that review and have concluded that steam void formation and subsequent water hammer effects during systems startup will not occur in Emergency Core Cooling-Systems as a result of reactor coolant leakage into these systems. For all four systems (i.e., Core Spray, Low Pressure Coolant Injection,-High Pressure Coolant Inj6ction, and Reactor Core Isolation Cooling) this conclusion is based on an analysis of the existing system confi-gurations using plant operating parameters. In each system, this condition can be modeled by a throttling process in which liquid water, at approximately 1050 psig, is throttled to a pressure slightly above atmospheric. -The resulting mixture, after throttling, would be of insufficient steam quality to i form a vapor pocket. Therefore, this phenomena is not applicable to Quad Cities Station.

Based on the results of this review, we consider this issue to be resolved. Should you have any additional concerns, please feel free to '

contact this office.

Very truly y urs, ib i e I. M. John n Nuclear Licensing nistrator im cc: Quad Cities Resident Inspector ,

i M. C. Parker - IDNS '

T. Ross - NRR s

t 450lK n

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