ML17252B136

Acknowledges Receipt of Letter Dated 12/14/1976 Regarding the New Test Program Relating to Feedwater Check Valve Local Leak-Rate Tests - Dresden Unit 3

ML17252B136
Person / Time
Site:	Dresden
Issue date:	02/01/1977
From:	Fiorelli G NRC/RGN-III
To:	Brian Lee Commonwealth Edison Co
References
BBS Ltr. #76-871, IR 1976025
Download: ML17252B136 (3)

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UNITED STATES

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NUCLEAR REGULATORY COMMISSION CENTRAL Fl LES REGION ill 799 ROOSEVELT ROAQ

. GLEN ELLYN; ILLINOIS 60137 FEB l 1977 Commom,-ealth *Edison Company Docket No. 50-249 ATTN:

Mr. Byron Lee, Jr.'.

Vice President P.O.* Box 767 Chicago, Illinois 60690 *

• Gentlemen:

• Thank you for your letter dated December 14, 1976, informing us of the new test program relating to feedwater check valve local leek-rate tests.

Your* program is presently under review by our office and has also been forwarded to our headquarters

.for a.generic review

• Your cooperation with us is appreciated *

. Sincerely yours,*

• ~** r;vp

\\..-Gaston Fiorelli, Chief Reactor. Operations and

• Nuclear Support Branch cc:

Mr. B. B. Stephenson Station Superintendent cc w/ltr dtd 12/14/76:

Central Files

• Reproduction Uni:t NRC 20b PDR

• Local PDR NSIC TIC Anthony Reisman, Esq.,*

Attorney i.

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Commonwealth. Edison

. Dresden Nuclear Power Station R.R. #1 Morris, Illinois 60450 Telephone 815/942-2920 BBS Ltr. #76-871 Hr. James G. Keppler, Regional Dtrector Direttorate of Regulatory Operations Regi~n.I II U.

s~ Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137

SUBJECT:

Dresden Statiori Feedwater Check Valve Local Leak-Rite Testing

REFERENCE:

Letter to J. G. Keppler from B. B. Stephens.on dated November 4, 1976 (Reportable O~currence report no. 50-249/1976-25)

Be~'ause feedwater check valve local leak-rate*tests (LLRT-'s) have repeatedly yielded excessive "as found" leakage results, a new test method has been developed which approximates as closely as possible the primary con-tainment conditions during a loss-of-coolant accident (LOCA).

The new test method involves pressurizing the volume upstream of the

• feedwater check valve with wate~.to approximat~ly 50 psig, then draining the *system and performing a LLRT utilizing isolation valve test procedures.

Current isolation valve test procedures specify a pneumatic pressure decay test as required by the Technical Specifications. *The station procedures will be, revised to reflect the new method of testing the feedwater check valves in the "as found" condition.

Development of ih~s new test method was based on typical postulated conditions following a LOCA.

The conditions selected were the design basis

• LOCA'followed by a loss.of off-site power, two failures which would 'result In the *lowest differential pressure available to seat the feedwater check valves *. For these conditions, reactor and containment pressure would be approximately 50 psig when the feedwater system pressure dropped to zerq as the result of the loss of off-site power.

Postulated LOCA'~ with less than

• design basis-size breaks would result in longer blowdown rates and potentially higher differential pressure available t6 seat the check valves following the subsequent loss of off-site power.

Sinte there would still be water on -the valves due to their position in the low point of the 1 ine, the new.

method of seating the valves with water is representative of accident conditions.

10 C.F~R~ part 50, appendix J, section I I l.C.1 specifies that each valve to be tested shall b~ closed by normal operation ~nd without any preliminary exercising or adjustments.* Feedwater check v~lve seating wi~h water-is con-*

sidered a normal operation since. the*valye is. no*rmally seated with water and a differe~tial pressure.*

Based on the results of testing performed during the Dresden Unit-3 i976 refueling outage, it is anticipated that the utilization of the new DEc 2 fl l9.l;;.

'*** test method will significantly r.e,duce the incidence of excessive "as found" leakage test results on the feedwater check valve*s.

(The method used to test the Unit-3 feedwater check valyes is described in _the refer:enced re-portable occurrence r-e-port.)

As. stated.previously, the:;*Dresden Station**LLRT procedure'.:'for the feedwater check valves will be *revised to include this new test fog met hod.

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• Station Superintendent Dresden Nuclear Power Station cc:

Director of Inspection & Enforcement

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Director of Management Information & Prbgram Control Fi Je/NRC

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