ML20244C817

Discusses GE 830103 Telcon Re Reported Failures of Shunt Trip Devices in GE Type AK-F-2-25 Breakers.Ge Recommended Against Use of Device for safety-related Application

ML20244C817
Person / Time
Site:	Pilgrim, 05000000
Issue date:	01/05/1984
From:	Beard J Office of Nuclear Reactor Regulation
To:	Butcher E Office of Nuclear Reactor Regulation
Shared Package
ML20235V135	List: ML20235V132 ML20235V152 ML20236V734 ML20236V815 ML20244C817 ML20244C903 ML20244C908 ML20244D387 ML20244D398 ML20244D438 ML20244D441 ML20245A445 ML20245A448
References
FOIA-87-644 NUDOCS 8401190238
Download: ML20244C817 (2)

Text

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! o-  !" NUCLEAR REGULATORY COMMISSION I wAsHmo TON, D. C. 2oS%

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MEMORANDUM FOR: Ed Butcher Section Leader '

Operating Reactors Assessment Branch / o f:- 2--

FROM: J. T. Beard Operating Reactors Assessment Branch

SUBJECT:

ATWS RECIRCULATION PUMP TRIP BREAKERS ,

A On January 3,1983 I received a telephone call from Mr. Max Fornwalt of J' General Electric Company, Plainville, Conn. The primary purpose of the call was to discuss reported failures of the shunt trip devices in GE "t,reaker" '

type AK-F-2-25 (which were reported to be similar to the AK-2-25 type) which-had occurred at the Pilgrim station. During -the' discussion, however, Mr.

Fornwalt st6ted that GE-Plainville would recournend against using the AK-F-2-25  ;

in any nuclear safety related (i.e. Class IE) application.

At. Pilgrim, GE type AK-F-2-25 devices are used to interrupt the field I excitation current of the motor-generator sets which drive the recirculation. -l flow pumps. While the AK-F-2-25 may resemble the AK-2-25, the two devices i are significantly different internally.* The AK-F-2-25 is a " field switch" l and not a true circuit. breaker, in that overcurrent protection is not.a feature.

The AK-F-2-25 has two poles that interrupt the d.c. field excitation current '

and a center pole that connects a resistor that dissipates the stored energy  :

in the field when the excitation is removed. The center pole of the AK-F-2-25 is operated by a special cam arrangement' intended to connect the fi~ eld cam . '!

resistor slightly before the main de poles open. Mr. Fornwalt. indicated that i the cam arrangement has a poor mechanical advantage (i.e. less than unity).

In the Pilgrim failures (April 1983), the shunt trip device diEl satisfactorily )

complete its function, in that it rotated the trip shaft and thereby started the trip action, according to Mr. Fornwalt. However, the cam arrangement failed to complete its intended action, and hence, the trip action was  !

inte rrupted. Accordingly, GE contends that the shunt trip device did not fail and that they remain . unaware of any shunt trip failures. I indicated -

that this description of the failure mechanism may not fully agree with information from the Region I, 'and the NRC resident inspector at Pilgrim, and specifically Inspection Report 50-293/83-09, dated June 6, 1983.

In discussing the AK-F-2-25 more generally, Mr. Fornwalt stated that, specifically because of the poor cam arrangement, GE stopped the manufacture of this design several years ago. He indicated that he had initiated action in April 1983 l (through GE) to advise end-users of this device that it should not be considered for Class IE applications. I explained that the application of tp devlee-etEllorim is now for ATWS protection and therefore has become

[diuclear that the AK-F-2-25 safety related should not be used (or Class IED for safety-related therefore should be replaced at Pilgrim. There is some uncertainty regarding Mr. Fornwalt.

applications and stated rathe this systems application thet needs to be resolved before any further action s'taken. .

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Based upon this infomation, I recomend the following ORia actions:

1. Call a. meeting with GE & Boston Edison (and support design organizations) to determine if there actually is a misapplication of the AK-F-2-25 device ~

in this system (i.e. eliminate misunderstandings and define the problem, if it exists). The Re'sident Inspector should also attend.

2. If a problem is defined,' tmat it as a 10 CFR 21 determination / notification.

at that time and, as such, turn it over to IE' for. action. -

1 J. T. Beard - l Operating Reactors Assessment Branch l

cc: F. Miraglia l G. Holahan V. Noonan J i

F. Rose -

1 R. Kendall P. Leech E. Rossi

- J. Zwolinski ' -

.E.- G reenman- .'

P. Swetland -;

l H. Eichenholz .

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