ML20244C252
| ML20244C252 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 04/12/1989 |
| From: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-PT21-89-067-000 CP-89-06, CP-89-6, PT21-89-067-000, PT21-89-67, TXX-89188, NUDOCS 8904200111 | |
| Download: ML20244C252 (2) | |
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908.3 7t/ELECTRlC Ref. #-.10CFR50.55(e)
April 12, 1989 W. J. Cahm '
Executive Vice President U. S.' Nuclear Regulatory Commission Attn: Document Control Desk
. Washington, D. C.
20555-SUBJECTf COMANCHE. PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NOS! 50-445 AND 50-446 6.9kV BREAKER CHARGING MOTOR LINKAGE SDAR:
CP-89-06-(INTERIM REPORT).
Gentlemen:
On March 13, 1989, TV Electric verbally notified the NRC staff of a deficiency involving the connecting linkage for the closing spring charging motors in the Class 1E 6.9kV switchgear.
This.is an interim report of a reportable deficiency under the provisions of 10CFR50.55(e)potentially-Description On three separate occasions for the Class 1E 6.9kV switchgear, the pin connecting the charging motor linkage to the breaker closing springs was missing or was found partially out.
This pin is held in place with two snap rings-One of these. rings was missing in all three instances. With a snap ring missing, the pin can work loose and fall out, rendering the connecting
-linkage for the charging motor inoperable. The charging motor will run
. continuously and will be unable to charge the breaker closing springs. The breaker will not close the next time operation is attempted.
To date the root cause of this deficiency has not be determined.
However, the cause is limited:to the following possibilities:
(a)
Snap ring may have failed due to a deficient design.
l (b)
Vendor may have inadvertently missed installing the snap rings in some of the breakers.
(c)
Snap rings may have been distorted or removed by field personnel while performing repairs or maintenance.
.This issue may affect all Class IE 6.9kV switchgear breakers at CPSES.
8904200111 890412 ADOCK0500g5 DR 4Y Ap
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TXX-89188-
- April 12, 1989
- Page 2 of 2 Safety Significance Several Class 1E 6.9kV switchgear circuit breakers are normally in the open
- position during plant operation.
If a charging motor linkage assembly fails and is not immediately detected, the associated Class IE equipment may not be able to perform its intended function.
Corrective Action To resolve this deficiency, Class 1E circuit breakers will be inspected. The inspections will verify that:
.(a)
The snap rings are installed at both ends of the connecting pin.
(b)
The snap rings are fully seated in the connecting pin grooves.
(c)
, Snap ring deformation does not exist.
Any snap rings found missing, partially seated or deformed will be docurented and new snap rings will be installed.
The Operations / Maintenance Procedure for 6.9kV breaker inspection and cleaning.
will be revised to add a sign-off step for visual inspections of the charging motor linkage pin and snap rings.
Additionally, a note will be added to the procedure to prohibit the re-use of snap rings after removal.
TV Electric will request the aid of the vendor in determining the final root cause of this deficiency.
Following this determination TV Electric will assess the adequacy.of the initial corrective actions and actions to preclude recurrence, and complete an evaluation of deportability pursuant to 10CFR50.55(e) or 10CFR21.
The scheduled completion date for implementation of the corrective actions described above is prior to Unit 1 fuel load for Unit 1 and prior to Unit 2 fuel load for Unit 2.
Sincerely, William J. Lahill, Jr.
WJH/vid c - Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (3)