ML20071A029

Submits Info Re Prevention of Steam Generator Water Hammer. Check Valves Removed to Assure Effectiveness of Controlled Closure Check Valves Upstream.Addl Check Valve Will Be Installed in Discharge Piping to Minimize Backleakage

ML20071A029
Person / Time
Site:	Byron, Braidwood, 05000000
Issue date:	02/15/1983
From:	Tramm T COMMONWEALTH EDISON CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
6002N, NUDOCS 8302180379
Download: ML20071A029 (3)

Text

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h Commonwealth Edison C

/ one First Mstionti Pizza Chictgo, Illinois

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C Addr:ss Riply to: Post Othee Box 767 N

Chicago, Illinois 60690 February 15, 1983 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulatio U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Byron Station Units 1 and 2 Braidwood Station Units 1 and 2 Waterhammer Prevention NRC Docket Nos. 50-454/455 and 50-456/457 References (a):

September 9, 1982 letter from

.R.

Tramm to H.

R. Denton (b):

February 10, 1983 letter from V.

G.

Copeland to the Byron ASLB Deer Mr. Denton:

This is to provide information regarding the prevention of steam generator waterhammer at Byron and Braidwood stations.

This supplements the information which was provided to the NRC in reference (a).

In reference (a), we indicated that constant feedwater flow through the upper steam generator nozzles would preclude the need for temperature monitoring of this piping.

We then believed that waterhammer could effectively be prevented without installation of that additional instrumentation.

Reu_atly, we have identified certain circumstances during plant startup and shutdown in which continuous feedwater addition is impractical.

Therefore, temperature monitoring instrumentation will be installed on the feedwater bypass piping close to the auxiliary nozzle.

This will alert the operator to potential waterhammer situations so that feedwater flow can be reinitiated without inducing waterhammer.

This has been discussed in the affidavit of Kenneth A. Ainger which was attached to reference (b).

Mr. Ainger's affidavit also noted that check valves in the auxiliary nozzle piping were being removed to assure the effective-ness of controlled-closure check valves farther upstream.

A typical diagram of this piping was provided in Figure 6 attached to reference (a).

The check valves being removed are the ones closest to the steam generators, identified in the typical diagram (Figure 6) as valve FWO37A.

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PDR

H. R. Denton February 15, 1983 Removal of these check valves necessitates the addition of other check valves to provide redundant back flow protection in certain piping.

Without additional check valves in the auxiliary feedwater pump discharge piping, there is only one check valve in the piping connecting the upper steam generator nozzles and the condensate storage tank via the auxiliary feedwater pump miniflow lines.

An additional check valve will therefore be installed in the discharge piping of each auxiliary'feedwater pump to minimize back-leakage through this path.

A revised version of Figure 6 is attached to document the location of these new valves.

Please, address further questions regarding this matter to this office.

One signed original and fifteen copies of this letter and the attached figure are provided for your review.

Very truly yours, fr i rT W T. R. Tramm Nuclear Licensing Administrator im Attachment 6002N

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