ML19295C019
| ML19295C019 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Byron, Braidwood, Quad Cities, Zion, LaSalle  |
| Issue date: | 02/21/1978 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8010150722 | |
| Download: ML19295C019 (1) | |
Text
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i FEB 211978 Docket Nos. 50-10, 50-237. 50-249, 50-254 l
50-265, 50-295, 50-304, 50-373, 50-374, l
50-454, 50-455, 50-456, 50.-457 l
Commonwealth Edison Company l
ATIN:
Mr. Byron Lee, Jr.
j
' ice President Post Offien Box 767 l
Chicago, IL 60690 I
i Gentlemen l
Enclosed is IE Eunetin No. 78-04 which requires action by you with l
regard to your power reactor facilities with an operating license l
or a construction permit.
Should you have any questions regarding this Eulletin or the actions required, please contact this office.
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Sincerely,
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James G. Keppler
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Director 4
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Enclosures:
1.
List of IE Bulletins Issued in 1978 l
cc w/enels:
Mr. B. B. Stephe'tson, Mr. R. Cosaro, Project Station Superintendent Superintendent I
Mr. N. Kalivinnakis,
/ Central Files Station Superintendent Reproduction Unit NRC 20b Mr. N. Wandke, Station PDR Superintendent Local ?DR Mr. L. J. Burke, Site
-NSIC Project Superintendent TIC Mr. Cunnar Sorensen, Site Anthony Roisman, Esq.,
Project Superintendent Attorney l
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- NRC FORM 313 (9 76) NRCM 0240 8 01015 0 7 M 'dru.s.oovsanusurra:
NTING OPPICae ISM -330-434 4
b U.S. NUCLEAR REGULATORY COT!ISSION OFFICE OF INSPECTION AND ENFORCE >ENT REGION III February 21, 1978 IE Bulletin No. 78-04 ENVIRON!ENTIL QUALIFICATION OF CERTAIN STEM MOUNTED LIMIT SWITCHES INSIDE REACTOR CONTAIhMENT Description of Circumstances:
As a result of a recent review by Westinghouse of the seismic and environmental qualifications of the electrical circuitry used for valve operation, certain stem mounted limit switches (SMLS) associated with various safety related valves were found not to be environmentally qualified for loss of coolant accident (LOCA) conditions. The switches in question are installed on certain motor operated valves and certain ait-operated valves lccated in primary containment. The functions of these valves provide either containment isolation or emergency core cooling system (ECCS) alignment during accident conditions.
Westinghouse has stated that for air operated valves the SMLS function is to provide " latch-in" capability to the actuation control circuitry of the valve.
It therefore is derignated as safety-related and cust receive seismic and environmental qualification.
The concern arises if the SMLS contacts short circuit during LOCA conditions.
If this occurs and if the valve control switch ic in the "AUT0" position (and control air is available to the valve operator),
the valve will move from its post accident position to the normal operating position when either the safety injection or contain=ent isolation signal is reset. A limited number of the switches are also used in safety related motor operated valve circuits in Westinghouse designed plants.
The attached Westinghouse Technical Bulletin, NDS-TB-77-13 issued an September 30, 1977, further describes the problem and provides sugges-tions for correcting the problem in air-operated valve actuation circuitry. One of the corrective actions considered by Westinghouse involves replacement of the switch with a switch that is environmentally qualified. An alter crective action utilizes a circuit modifi-
' 2re associated with the air-operated valve affect on valve operation can occur during DUPLICATE DOCUMENT Entire document previously entered into system under:
ANO YbNW No. of pages:
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