TXX-7041, Interim Deficiency Rept CP-87-21 Re Effect of Thermolag on Cable Derating Factors.Initially Reported on 870617. Identified Cables Exceeding Prescribed Ampacity Rating Will Be Reworked.Next Rept Expected by 880406
| ML20237E702 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 12/23/1987 |
| From: | Counsil W, John Marshall TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| CP-87-21, TXX-7041, NUDOCS 8712290137 | |
| Download: ML20237E702 (2) | |
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M MM Log # TXX-7041 File # 10110
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908.3 7t/ELECTR/C Ref. # 10CFR50.55(e) wmam c. counsa December 23, 1987 twa,n vu, em,&,,,
U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NOS. 50-445 AND 50-446 EFFECT OF THERM 0 LAG ON DERATING FACTORS SDAR: CP-87-21 (INTERIM REPORT)
Gentlemen:
On June 17, 1987, we verbally notified your Mr. H. S. Phillips of a deficiency involving the effect of thermolag on cable derating factors.
We are reporting this issue under the provisions of 10CFR50.55(e).
The required information follows.
Description Recent evaluations have established derating factors of 31% for single trays and 20% for single conduits enclosed in thermolag.
These derating factors are larger than the derating factor (10%) used in the initial cable sizing calculations.
Our evaluation to date has revealed that 74 cables could have exceeded their ampacity rating if the thermolag enclosing these cables was left in place.
This deficiency was caused by recent evaluations by the ve'ndor'which have altered previously accepted cable derating factors.
This condition is limited to power cables protected by thermolag.
Safety Implications Failure to consider the additional derating of power cables due to thermolag installation could cause the power cables to exceed the design temperature rating and result in the misoperation of the associated Class 1E circuits.
This issue represents a significant final design deficiency as approved and released for construction and, were it to have remained uncorrected, could have adversely affected the safety of plant operations.
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8712290137 871223 PDR ADOCK 05000445 s
DCD a Nonn otne screes LB 81 Dallas. Tnn MOI
TXX-7041 December 23, 1987 Page 2'of 2 Corrective Action Cables identified which exceed prescribed ampacity rating due to thermolag will be reworked to remove the thennolag from the raceways or the cable size will be increased.
A definitive schedule for Units 1 and 2 will be provided in our next report.
Our next report on this issue will be submitted no later than April 6,1988.
Very truly yours, W.G. Gaul W. G. Counsil By:
J..S. Marshall Supervisor,.*
Generic Licensing JDS/grr c - Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (3)
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