ML20209C734

Forwards Response to Request for Info Re Encl H Schierling 840216 Memo.Substantial Number of GE Magne-Blast Breakers w/ML-13 Operating Mechanism for Svc at 4 Kv Level Used

ML20209C734
Person / Time
Site:	Diablo Canyon
Issue date:	02/29/1984
From:	Miraglia F Office of Nuclear Reactor Regulation
To:	Eisenhut D Office of Nuclear Reactor Regulation
Shared Package
ML17083B484	List: ML20209C687 ML20209C692 ML20209C725 ML20209C729 ML20209C734 ML20209C742 ML20209C774 ML20209C779 ML20209C786 ML20209C810 ML20209C853 ML20209C869 ML20209D170 ML20209D204 ML20209D416 ML20209D421 ML20209D450 ML20209D560 ML20209D649 ML20209D703 ML20209D864 ML20209D903 ML20209E021 ML20209E030 ML20209E037 ML20209E052 ML20209E145 ML20209E211 ML20209E268 ML20209E506 ML20209F952 ML20209G177 ML20210E664 ML20210E745 ML20210E799 ML20210E811 ML20210E916
References
FOIA-86-197 NUDOCS 8403080280
Download: ML20209C734 (3)

Text

.

psom Yd' ' , UNITED STATES

'g_

.  ! '1 ) ,. NUCLEAR REGULATORY COMMISSION

';; g' y j WASHINGTON, D. C. 20555 Q'2 7 k...../ pgg 2 i 3>4 l 1

itEMORANDUM FOR: Darrell G. Eisenhut, Director l Division of Licensing FROM: Frank J. Miraglia, Assistant Director for Safety Assessment, DL

SUBJECT:

DIABLO CANYON: GE MAGNE-BLAST CIRCUIT BREAKERS The following information is provided in response to your request marked on the enclosed note from Hans Schierling dated February 16, 1984.

The Diablo Canyon station uses a substantial number of the GE Magne-Blast breakers with the ML-13 operating mechanism for service at the 4 KV level.

The Region reports that 21 of these breakers are in safety-related applications.

GE issued a Service Advice Letter dated February 17, 1977 on this breaker discussing a potential problem with the teflon sleeve bushings. The Region reports that the Diablo Canyon station has no record of receiving this vendor information and that the vendor has no record of having sent it to Diablo.

We talked with Mr. Dick Miller, Manager of Design Engineering at the GE Switchgear Division in Philadelphia, where the Magne-Blast breaker is manufactured. He stated that GE had experienced 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 operating mechanism. In his opinion, the increased clearances could cause difficulties in closing the breaker, but that the tripping function should not be af#ected grea tly. Since the problem is batch-related, most of the teflon bushinos are not affected. Therefore, GE's advice was to keep an eye or 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.

The Region told us that in September 1983 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 close 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 the licensee initiated an overhaul program for the Magne-Blast breakers.

The Region stated that they are following this overhaul activity end will reovire, 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 rete are discussed below.

Contact:

[

J. T. Beard, NRR x27465

]

(fD$b80280g/)

se ~

Darrell G. Eisenhut 1. It this a generic problem? The Region initially 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 believed to be used widely, our daily reviews of operating events are not showing problems with these breakers beyond an occasional random failure. We also asked AE0D to do a computer search of reported failures of Magne-Blast breakers. This search confirms that failures of this breaker are not occurring in significant numbers. Therefore, we and the Region now agree that this matter should not be treated as a generic problem.

However, we do believe that IE should issue an Infomation Notice to assure that all licensees receive a copy of the GE Service Advice Letter.

2. Is complete resolution needed prior to criticality? As discussed above, the ~egion will assure complete resolution prior to criticality.

We agree w",n this action. Since the licensee instituted an overhaul program in September 1983, completion is not expected to cause any undue delay in criticality.

3. Part 21 compliance? The licensee is considering the Part 21 aspects of the breaker problem now. The Region will followup to assure an appropriate conclusion.

4 What is the cualification of the breakers? Clearly, some of these breakers are in safety-related service. However, since they are located outside containment in non-hostile environments, the degree of special qualification beyond that for commerical service may be minimal. The Region will assure that each is appropriately qualified.

We will reauest that IE issue an Information Notice on the 1977 Service Advice Letter, by a separate memo.

He believe that the information above is sufficient to close-out this matter, f

- W Frank J. bra ia, Assistant nirector for Safety Assessment, DL

Enclosures:

As stated cc w/ enclosures:

See next page

e 6

N FEB 2 Darrell G. E.isenhut cc w/ enclosures:

T. flovak G. Knighton N

M. Srinivasan E. Jordan J. Partlow R. Baer E. Rossi T. Ippolito P. Cross T. Bishop H. Canter fi. Mendonca l

l 4#

1