ML16341C139
| ML16341C139 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 04/26/1984 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML16341C140 | List: |
| References | |
| NUDOCS 8405080280 | |
| Download: ML16341C139 (4) | |
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UNiTEDSTATES NUCL'EAR REGULATORY COMMISSlON W4SHINGTQN' C. 20555 2,9~
MEMORANDUM FOR=
DarreT1 G. Eisenhut, Director Division of Licensing FROM The Region toTd us that in September I983 Diablo Canyon experienced "more than normal wear" on one of its Magne-Blast breakers.
When one of the emergency diesel generator output breakers failed to Hose during a test, the teflon bushing was. found deteriorated to the point of metal-to-metal contact.
They also'found some corrosion problems.
At this point'he licensee initiated an overhauT program for the Magne-Blast breakers.
The Region stated that they are following this overhaul activity and will
- require, as a minimum, that the breakers in safety-related service be refurbished prior to criticality.
The specific. questions raised by the project manager in the enclosed note are discussed below.
Frank J. Niraglia, Assistant Director for Safety Assessment, DL SUBJECT."
DIABLO CANYON:.
GE MAGNE-BLAST,CIRCUITBREAKERS
'J The foTlowing information. is provided in response to your request marked on the encTosed: note from Hans SchierTing dated February 16, 1984 The Diablo Canyon statioe uses a" substantiaT number of the. GE Magne-Blast breakers with. the ML-I3 operating mechanism for service at the 4 KV level.
The Region reports that ZI of these breakers are in safety-related applications.
GE issued-a Service Advice Letter dated February IT,. I977 on this breaker discussing a potential problem with the teflon sTeeve bushings.
The Region reports that the GiabTa Canyon station has no record of receiving this vendor information and that. the vendor has no record of'aving sent it to Diablo.
We talked with'%. Gick'Ruler., Manager of Design Engineerinp at the GE Switchgear. Hivtsfarr in PhiTade1phia where the Magne-BTast breaker is manufactured He stated-that GE had; experiencecf:
some. batch-to-batch inconsistency problems with the.. Tuf-Loc.
bushings Some bushings would not hold up start to crush and cause increased clearances in the operatinr mechanism En his opinion, the increased clearances could cause difficulties irr closing the breaker, but that the tripping function should not be affected greatly.
Since the problem is batch-related, most of the teflon bushings are not affected'herefore GE's advice was to keep an eye on the breakers (i.e, increased surveillance) and if problems developed, a bronze bushing could be used The vendor advice did not request that all bushings be replaced A copy of the GE letter is enclosed.
Contact:
J. T. Beard, NRR x27465
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DarreTT G. Eisenhut 1.
It this a generic probTem.
The Regiorr initiaTTy thought that the problem was generic. and accordingly sent a
memo (dated February 23, 1984) to Ed Jordan.
In our telecon on February 24, 1984 we pointed out that, while the Magne-Blast is beTieved to be used wideTy, our daiTy reviews of operating events are not showing problems with these breakers beyorrd'an occasionaT random failure.
Me also asked AEOD to.do a computer search of reported failures of Magne-Slast breakers.
This search confirms that failures of this breaker are not occurring in significant numbers Theref'ore, we and the Region now agree that'tris matter should not be treated. as a generic problem
'However we do bel.ieve that IE should issue an Informatiorr Notice to. assure that aTT Ticensees receive a copy of the GE Service Advice Letter 2.
3 I's complete resolution needed prior to criticality?
As discussed above, the Region wiT1 assure complete resolution prior to criticality.
Me agree with this. action.
Since the licensee instituted an overhaul program in September 1983, completion is not expected to cause any urrdue delay in criticaTity.
Part ZI compliance7 The Ticensee is considering the Part ZI aspects of'.the breaker probTem now.
The Regiorr wiTT fallowup to assure an appropriate concIustorr What is the quaTificattorr of.the breakers?
- Clearly, some of these breakers are Trr safety-reTated service.
However, sirree they are located outside-containment. in non-hostile environments, the degree of speciaT quaTification beyond that for commerical service may be minima1 The Region wiTl assure that each is appropriately qualified.
Me wiTl request that IE issue an Information Notice on the 197T Service Advice Letter, by a separate memo.
We believe that the information above is sufficient to close-out this matter.
Enclosures:
As stated Frank J.
ra ia, Assistant Director for Safety Assessment, DL cc w/enclosures:
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