ML19256F705
| ML19256F705 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 12/07/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Crane P PACIFIC GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7912200236 | |
| Download: ML19256F705 (1) | |
Text
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UNITED STATES Ik NUCLEAR REGULATORY COMMISSION 3
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WALNUT CRE E K, CALIFORNI A 94596 December 7, 1979 Docket Nos. 50-133 Pacific Gas and Electric Company 77 Beale Street San Francisco, California 94106 Attention: Mr. Philip A. Crane, Jr.
Assistant General Counsel Gentlemen:
Enclosed is IE Bulletin No. 79-28 which requires action by you with regard to your power reactor facility (ies) with an operating license or a construction permit.
Should you have questions regarding this Bulletin or the actions required of you, please contact this office.
Sincerely, lcW wfCn R. H. Engelken Director
Enclosures:
1.
List of Recently Issued IE Julletins cc w/ enclosures:
W. Barr, PG&E W. Raymond, PG&E E. Weeks, PG&E, Humboldt Bay 1775 003 7912200 25b
UNITED STATES SSINS No.: 6820 NUCLEAR REGULATORY COMMISSION Accession No.:
GFFICE OF INSPECTION AND ENFORCEMENT 7910250505 WASHINGTON, D.C.
20555 Decenber 7, 1979 IE Bulletin No. 79-28 POSSIBLE t'ALFUNCTION OF NAMC0 MODEL EA180 LI'1IT SWITCHES AT ELEVATED TEt'PERATilRES Description of Circunstances:
The NRC has been recently advised throuah a 10 CFR 21 report from NAMC0 Controls that a malfunction of a NA"C0 Model EA180 sten mounted limit switch (S'1LS) occurred at the Cooper Nuclear Station.
Investigation into the switch failure by the licensee revealed yellow and brown " crystal-like" resin deposits on the internal components of the switch. The affected switch is located inside the drywell containnent at this facility and was being used as the replacement switch for an unqualified SPLS previously identified in IE Bulletin f6s.
78-04 and 79-01.
According to the nanufacturer, the problem was traced to a batch of top cover gaskets of which some were over-impregnated and insufficiently heat cured.
It has been determined that this condition can leave an uncured residue of " Loctite" in the gasket, which vaporizes at sustained tenceratures above 1750F. To correr:t the problem, the nanufacturer has revised oroduction techniques beginning Septerber 1979 in order to better control the iroregnation process and to procerly heat ;ure the gaskets following incregnation. This oroblem is unique to all NAMC0 Fodel EA180 series switches received by licensees after 'farch 1,1979.
According to the manufacturer, the susoect switches can be identified by checkina the date code which is a 4 digit number starped on the conduit boss of the switch housing.
flAMCO recomnends that any C180 series switch with a date code between 02-79 through 08-79 should havr.. s top cover qasket replaced. Also, licensees should request from their suppl'.ers of equipnent on which UAMCO EA180 series switches are used that they check their inventory and replace top cover gaskets on switches date coded between 02-79 through 08-79.
The enclosed letter from NAMC0 further describes the high-tencerature environ-nental problem with the top cover gaskets used in their FA180 switches and provides recommendations to correct the problem. Accordinq to NAMC0, this letter has been sent to each custoner who was shipped EA180 switches between February 21, 1979, and August 24, 1979.
Action to be Taken by Licensees of Power Reactor Operatina Facilities and Holders of Construction Pemits:
1.
Determine if your facility has i switches in any safety-related e containment, including valve 00si DUPLICATE DOCUMENT containment isolation valves.
Entire document previously 004 ontered into syste= under:
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