ML20071E426
| ML20071E426 | |
| Person / Time | |
|---|---|
| Site: | Zimmer |
| Issue date: | 02/23/1983 |
| From: | Borgmann E CINCINNATI GAS & ELECTRIC CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, QA-1723, NUDOCS 8303100221 | |
| Download: ML20071E426 (2) | |
Text
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THE INCINNATI GAS & ELECTRIC COMPANY W--
CINCINNATI. OHIO 45201 February 23, 1983 QA-1723 L A. SQROMANN srwion vect parsiDENF
'i. S. Nuclear Regulatory Commission Aegion III Roosevelt Rd.
Glen Ellyn, Illinois 60137 Attention:
Mr. J.
G.
Keppler Regional Administrator RE:
WM. H. ZIMMER NUCLEAR POWER STATION UNIT 1 10CFR50.55(e) - ITEM E BROWN BOVERI 125VDC CONTROL DEVICE FAILURE ON 6.9KV AND 4.16KV SWITCHGEAR DOCKET NO. 50.358, CONSTRUCTION PERMIT NO. CPPR-88, W.O.
- 57300, JOB E-5590, FILE NRC-7, E-39 Gentlemen:
This letter constitutes an interim report concerning the subject condition reported to the NRC on February 2, 1983 as a potentially reportable deficiehey under the requirements of 10CFR50.55(e).
Brown Boveri (formerly ITE Imperial) circuit breakers, models 7.5KV and 5HK350 are used at Zimmer in seventy-two (72) 6.9KV and 4.16KV circuit ' breakers for both essential and non-essential service.
The circuit breakers were supplied with a control device, model no. 191921 T6-R.2, which is rated for 125VDC.
This device is utilized'in the closing circuit of the circuit breaker, provides anti-pump protection, and controls the spring charging motor.
The plastic molded portion of the limit switch contact assembly in this device is cracking.
When this occurs the contacts fail to operate and resulting in the failure of the circuit breaker to operate.
Four (4) of the control devices have failed in this manner.
A failed control device was returned to the manufacturer.
The manufacturer verbally stated the failure of the contact assembly was caused by over travel of the operating arm due to insufficient clearance between the limit switch and the operating arm.
The manufacturer had previously issued an Instruction Bulletin (IB-7803) that furnished instructions for installation 8303100221 830223 DR ADOCK 05000 8
MAR 0 7 E63 9
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f Pcga 2 10CFR50.55(e) - Item E-39 February 23, 1983 and adjustment of the revised limit switch stop for the subject circuit breakers.
However, this bulletin deals with replacement control devices on circuit breakers built prior to 1978.
The devices that are failing at Zimmer are original devices on circuit breakers built prior to 1978.
Circuit breakers built after 1978 were adjusted and are not subject to this problem.
At our request, the manufacturer is revising the bulletin to provide inspection criteria and corrective action for original circuit breakers built prior to 1978.
The corrective action for this deficiency to be implemented at Zimmer will be developed after receipt of the revised instruction bulletin.
Our next report, to be submitted on April 30, 1983, will identify the corrective action required to resolve this deficiency.
We trust the above will fulfill the requirements of an interim report under 10CFR50.55(e).
Very Truly Yours, THE CINCINNATI GAS & ELECTRIC COMPANY
=-
E.
A.
BORGMANN Senior Vice President EAB/WPC/ejc cc:
NRC Office of Inspection and Enforcement Washington, D.C.
20555 NRC Senior Resident Inspector ATTN:
W.
F.
Christianson NRC Zimmer Project Inspector Region III
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