ML20003F182
| ML20003F182 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 04/10/1981 |
| From: | Tramm T COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8104200365 | |
| Download: ML20003F182 (2) | |
Text
.- **
Ctmmtnw:::lth Edis:n M
One First Nationat Pratt Chicaco. tihnois y
Address Reply to: Post Othee Box 767 Chicago, litinois 60690 p.lJIU,h c('{k-)kdd h
,sses April 10, 1981
[
j b
"'gY '
Mr. James G. Keppler, Director Directorate of Inspection and Enforcement - Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137
Subject:
Byron Station Units 1 and 2 Braidwood Station Units 1 and 2 Intermittent Contact Operation Of Type W-2 Switch NRC Docket Nos. 50-454, 50-455, 50-456-and 50-457 References (a):
July 23, 1980 letter from W. F. Naughton to J. G. Keppler (b):
July 30, 1980 letter from G. Fiorelli to C. Reed
Dear Mr. Keppler:
This is to provide additional information regarding the final resolution of the W-2 switch problem which was reported on June 23, 1980.
Reference (a) provided the required written report on this 50.55(e) deficiency.
We also indicated that decisions on design changes were being postponed until further investigations could be completed by Westinghouse.
That work has now been completed and this constitutes our final report on the W-2 switches.
The Westinghouse investigation consisted of detailed examinations and tests on new switches ano on switches known to have experienced intermittent contact operation after installation.
The purpose of this work was to verify oesign adequacy and to identify the source of internal contamination believed to be the cause of the problem.
The design review and testing confirmed the adequacy of the basic switch design.
It was determined that internal switch contaminants could produce switch malfunctions.
External particulate contamination was proven to be an unlikely cause of malfunction.
Examination of contact surf aces via Scanning Electron Microscope (SEM) ana X-ray (KEVEX) indicated that products introduced durng electroplating are a possiole cause of malfunction.
SoI7 3
s 10 42003(oS f
-2 As a result of these investigations, the switch manufacturing process has been revised to include additional cleaning steps to reduce internal contamination during assembly.
The electroplating process is also being revised to minimize possible contaminants.
At Byron and Braidwood all W-2 switches will be replaced with switches manufactured to the revised assembly and electroplating procedures.
The new switches cre expected to be sufficiently reliable and the wiring changes which were orignally recommended will not be made.
Constant monitoring of contact continuity is unnecessary because plant oesign includes redundaacy adequate to cope with isolated random equipment failures.
Please direct questions regarding this matter to this office.
Very truly yours,
[fMeIW T. R. Tramm Nuclear Licensing Administrator Pressurizeo Water Reactors Director of Inspection ands #
cc:
Enforcement 22228