ML19254F858
| ML19254F858 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 11/02/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| NUDOCS 7911190206 | |
| Download: ML19254F858 (1) | |
Text
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NUCLEAR REGULATORY COMMISSION
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1990 N. CALIFORNIA BOULEVARD
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SulTE 202. WALNUT CREEK PLAZA
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Docket No. 50-312 Sacramento Municipal Utility District P. O. Box 15830 Sacramento, California 95813 Attention: Mr. John J. Mattimoe Assistant General Manager Gentlemen:
Enclosed is IE Bulletin No. 79-25 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, f L, a r' R. H. Engelken' Director
Enclosures:
1.
List of IE Bulletins Issued in the Last Six Months cc w/ enclosures:
R. J. Rodriguez, SMUD L. G. Schwieger, SMUD 1345 278 h
vo1119, 2 0 b
UNITED STATES SSINS No.: 6820
!0CLE M REGULATORY CnMMISSION Accession ?!o. :
OFFICE OF INSPECTION AND ENFORCEMENT 7908220139 VASHINGTON, D. C.
20555 November 2, 1979 IE Bulletin No. 79-25 FATUIRES nF WESTINGHOUSE RF0 RELAYS IN SAFETY-RELATED SYSTEMS Description of Circunstances:
While conductino resoonse time tests on Uestinghouse RF0 relays at the 9. B.
Robinson facility, two relays were found to be stuck in the eneroized cosition with the coil de-energized. The twenty relays being tested were installed scares and orovided no safety-related or ocerational ' unction. The subiect relay is identified as a Westinchouse Electric Corocration tvoe BFD, style 5069A95G03, coil style 1259C71G19. Upon disenvery of the tw stuck relays in the test cro-oran, the licensee conducted resoonse tests on similar relays installed in the Reactor Protection Systen. Durino this additional testing a reactor trio relay was found to be stuck in the energized position.
Detailed investiaation of the eroblem by the licensee's staff indicated that the armature was sticking to the amature stoo post. This condition is ancarently created when heat generated by normally energized coils causes a softening and resultant flow of epoxy adhesive used to attach the nagnetic antistick disc to the too of the amature stoo cost.
When sufficient adhesive flows to the top of the armature stoo, the amature becomes bonded to the stop post, resulting in the relay sticking in the energized position.
The ecoxy adhesive had also discolored to a dark brown as opoosed to clear in new relays.
After reviewino this oroblen, Westinghouse issued a service letter dated December 6, 1978. A cooy of this letter is enclosed for your infomation and acoroariate use. Westinghouse reconmended reolacinq affected relays with a relay identified as NSF0, style 5072A49, coil style 1271C50G01,125/130 Volt DC
/ 10 cercent.
nuring installation and testina of the new NRF0 relays identified by Westinghouse, H. B. D.obinson detemined that some of the new style relays exhibited narqinal or unsatisfactory armature overtravel. fn investication of the oroblen by Festinchouse indicated that the insufficient overtravel was limited to eicht and twelve cole rodels of the NPFD relays. Westinchouse issued a Technical Bulletin
' ISO-T3-79-05 to Licensees. A cooy of this Tcchnical Bulletin is also enclosed for your information and use. Yestinahouse raccrrended a testina rethod for identifyinq relays with insufficient over travel and also recorrended reolace-rent of relays with insufficient overtravel.
Action to be Taken by Licensees:
For all power reactor facilities with 1.
Determine whether or not the foll DUPLICATE DOCUMENT used or olanned for use in safety 1.345 279 Entire document previously a.
Tyne BFD, style 46E7352 or 7 entered into system under-b.
Type BF0, style 5069A95, coi M
p c.
Type BFD, style 5072A49, coi ANO
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