ML19210B348
| ML19210B348 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 03/01/1974 |
| From: | Arnold R METROPOLITAN EDISON CO. |
| To: | |
| Shared Package | |
| ML19210B347 | List: |
| References | |
| NUDOCS 7911070674 | |
| Download: ML19210B348 (2) | |
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n,-m METROPOLITAN EDISON COMPANY POST OFFICE BOX 542 READING, PENNSYLV ANI A 19603 TELEPHONE 215 - 929-36o1 M A.1 0 1 13 N Dr. D. F. Knuth, Director Directorate of Regulatory Operations Office of Regulation U. S. Atomic Energy Commission Washington, D. C.
20545
Subject:
Three Mile Island Nuclear Station Unit 1 Docket No. 50-289 Physical Cable Count vs. Cable Tray Summary Quantities
Dear Dr. Knuth:
The AEC was notified on January 30, 1974 of a situation which may be considered reportable under 10CFR50.55(e)(1)(iii), " Conditions of Construction Permits". This relates to a lack of separation of seven circuits in the vicin-ity of the HVAC panel underneath the Control Room.
DESCRIPTION OF INCIDENT An independent audit by GPU Service Corporation was performed during the month of January 1974.
Inspection of cable trays underneath and near the entrances to panels in the Control Room revealed that four engineered safeguard and three associated cables were approximately two feet too long in the termi-nated portion underneath the HVAC panel. This caused the cables exiting frem the red cable tray 219 to sag into the green cable tray 246 for a distance of
,aprinximately two feet. These cables had been satisfactorily inspected and at least one of the cables had been electronically traced prior to the cables being terminated. These cables were run in January of 1972.
ANALYSIS OF THE SAFETY IMPLICATION Investigation of this audit finding revealed that both cable trays contained only control circu'.ts.
Six of the cables involved are protected by fuses or circuit breakers.
Die maximum load current for each of these circuits is less than one ampere.
The remaining non-safeguard circuit (EA-310) is protected externally by a circuit breaker and the circuit is fused within the HVAC panel. The maximum load current is less than eight amperes.
1584 235 3 14.85 N 911070 {7t{
w Dr. D. F. Knuth.
One of the circuits (CQ-163) is the actuation control for isolation valve AH-V-1B and is located in the red tray. This is a motor operated valve which is normally in the closed condition.
The redundant isolation valve (AH-V-1A) has its actuation control circuit located in the green tray. This valve is piston operated and will close on a loss of power. All the cables used in engineered safeguard cable trays have flame retardant insulation.
If the cables remained in this position and in the unlikely event that a fire should occur in either tray, the effect on the protective system would be minimal because the valve AH-V-1A would close on a loss of power.
CORRECTIVE ACTION The circuits are being routed in a manner such that no cables can sag into the green cable tray 246. This work will be completed prior to fuel loading.
EVALUATION The independent audit by GPU Service Corporation has reviewed other similar areas underneath the Control Room and found all cables in cable trays were routed per separation and design criteria. The lack of separation for these seven cables is considered an isolated event. No further action is necessary.
Very truly yours,
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/t 'u' R. C. Krnold Vice President brh cc:Mr. J. P. O'Reilly Mr. W. A. Verrochi 1584 236