ML19256F707
| ML19256F707 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 12/07/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| NUDOCS 7912200248 | |
| Download: ML19256F707 (1) | |
Text
/'ga asce,,o, UNITED STATES 8\\'
NUCLEAR REGULATORY COMMISSION
(,
n REGION V o, -
g 1990 N. C AL* FORNI A BOULEVARD 4,
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SUITE 202, WALNUT CREEK PLAZA WALNUT CREEK, CALIFORNIA 94596 December 7, 1979 Docket ilo. 50-312 Sacramento Municipal Utility District P. O. Box 15830 Sacramento, California 95813 Attention: Mr. John J. Mattimoe Assistant General Manager Gentleman:
Enclosed is IE Bulletin fio. 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,
}b LT5~scG R. H. Engelken Director
Enclosures:
1.
IE Bulletin tio. 79-28 2.
List of Recently Issued IE Bulletins cc w/ enclosures:
R. J. Rodriguez, SMUD L. G. Schwieger, SMUD 1774 354 7 9122 0 0.2,, y h O
UtlITED STATES SSINS No.: 6820 flUCLEAR REGULATORY CouMISSION Accession No.:
OFFICE OF IflSPECTION Afl0 EflFORCEftFNT 7910250505 WASHIfiGT0!!, D.C.
20555
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December 7, 1979 IE Rulletin No. 79-28 POSSIBLE P'ALFUNCTInM OF flAMC0 MODEL EA180 LIMIT SWITCHES AT ELEVATED TEt'PERATURES Description of Circunstances:
The No.C has been recently advised throuah a 10 CFR 21 recort fron ?!AMC0 Controls that a malfunction of a NA"C0 Model EA180 stem nounted limit switch (SMLS) occurred at the Cooper fluclear Station.
Investigation into the switch failure by the licensee revealed yellow and brown " crystal-like" resin deoosits on the internal cornonents of the switch. The affected switch is located inside the drywell containment at this facility and was being used as the replacement switch for an unqualified S!'LS oreviously identified in IE Bulletin flos.
78-04 and 79-01.
According to the manufacturer, the problem was traced to a batch of top cover gaskets of which some were over-inpreanated and insufficiently heat cured.
It has been detennined that this condition can leave an uncured residue of " Loctite" in the gasket, which vaporizes at sustained tenceratures above 175 F.
To correct the problen, the nanufacturer has revised oroduction techniques beginnino September 1979 in order to better control the iroregnation process and to procerly heat cure the caskets following incregnation.
This oroblen is unique to all flAMC0 Model EA180 series switches received by licensees after flarch 1,1979. According to the manufacturer, the susoect switches can be identified by checkino the date code which is a 4 digit number starped on the conduit boss of the switch housing.
flAMCO recomnends that any EA180 series switch with a date code between 02-79 through 08-79 should have its ton cover qasket replaced. Also, licensees should request from their suppliers of equipment on which itAMC0 EA180 series switches are used that they check their inventory and replace top cover caskets on switches date coded between 02-79 throuch 08-79.
The enclosed letter from flAPC0 further describes the high-tencerature environ-nental problem with the top cover qaskets 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 Peactor Goeratino Facilities and Holders of Construction Permits:
1.
Determine if your facility has i switches in any safety-related e containment, including valve ons DUPLICATE DOCUMENT containment isolation valves.
Entire document previously entered into system under:
.,f No. of pages: