ML19254F848
| ML19254F848 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 11/02/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Eric Turner HOUSTON LIGHTING & POWER CO. |
| References | |
| NUDOCS 7911190183 | |
| Download: ML19254F848 (1) | |
Text
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.i UNITED STATES n arc,D u
u NUCLEAR REGULATORY COMMISSION o
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REGloN IV E) 611 RYAN PLAZA DRIVE, SUITE 1000
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'j ARLINGTON, TEXAS 76012
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November 2, 1979 g
In Reply Refer To:
RIV Docket Nos. 50-498/IE Bulletin No. 79-25 50-499/IE Bulletin No. 79-25 Ilouston Lighting & Power Company ATTN:
Mr. E. A. Turner, Vice President Power Plant Construction and Technical Services Post Office Box 1700 IIouston, Texas 77001 Gentlemen:
Enclosed is IE Bulletin No. 79-25 which requires action by you with regard to your power reactor facilities 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, x Le b~ A 1. Seyfri Director
Enclosures:
1.
List of IE Bulletins Issued in the Last Six Months 1345 236 h
7911190
UNITED STATES SSINS No.: 6820 NUCLEAR REGULATORY COMMISSION Accession No.:
OFFICE OF INSPECTION AND ENFORCEMENT 7908220139 WASHINGTON, D. C.
20555 IE Bulletin No. 79-25 Date: ~ November 2, 1979 Page 1 of 2 FAILURES OF WESTINGHOUSE BFD RELAYS IN SAFETY-RELATED SYSTEMS Description of Circumstances:
While conducting response time tests on Westinghouse BFD relays at the H. B.
Robinson facility, two relays were found to be stuck in the energized position with the coil de-energized. The twenty relays being tested were installed spares and provided no safety-related or operational function. The subject relay is identified as a Westinghouse Electric Corporation type BFD, style 5069A95G03, coil style 1259C71G19. Upon discovery of the two stuck relays in the test pro-gram, the licensee conducted response tests on similar relays installed in the Reactor Protection System.
During this additional testing a reactor trip relay was found to be stuck in the energized position. Detailed investigation of the problem by the licensee's staff indicated that the armature was sticking to the armature stop post.
This condition is apparently created when heat generated by normally energized coils causes a softening and resultant flow of epoxy adhesive used to attach the magnetic antistick disc to the top of the armature stop post.
When sufficient adhesive flows to the top of the armature stop, the armature becomes bonded to the stop post, resulting in the relay sticking in the energized position. The epoxy adhesive had also discolored to a dark brown as opposed to clear in new ralays.
After reviewing this problem, Westinghouse issued a service letter dated December 6, 1978. A copy of this letter is enclosed for your information and appropriate use. Westinghouse recommended replacing affected relays with a relay identified as NBFD, style 5072A49, coil style 1271C50G01, 125/130 Volt DC 10 percent.
During installation and testing of the new NBFD relays identified by Westinghouse, H. B. Robinson determined that some of the new style relays exhibited marginal or unsatisfactory armature overtravel.
An investigation of the problem by Westinghouse indicated that the insufficient overtravel was limited to eight and twelve pole models of the NBFD relays. Westinghouse issued a Technical Bulletin NSD-TB-79-05 to Licensees. A copy of this Technical Bulletin is also enclosed for your information and use. Westinghouse recommended a testing method for identifying relays with insufficient overtravel and also recommended replace-ment of relays with insufficient overt DUPLICATE DOCUMENT345 237 Entire document previously entered into system under:
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