ML20195H720
| ML20195H720 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 01/11/1988 |
| From: | Counsil W TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| CP-87-134, TXX-88064, NUDOCS 8801200324 | |
| Download: ML20195H720 (2) | |
Text
-.
I 2
M E ".""""
log # TXX-88064 i
Fi1e # 10110
.=
C 908.3 Ref. # 10CFR50.55(e) 7UELECTR/C EST,id/",$,.<
January 11, 1988 U. S. Nuclear Regnlatory Comission Attn:
Document Control Desk Washington, D.C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION DOCKET NOS. 50-445 AND 50-446 CLASS 1E AC ELECTRICAL SYSTEM SDAR:
CP-87-134 (FINAL REPORT)
Gentlemen:
On December 18, 1987, we verbally notified your Mr. R. F. Warnick of a deficiency involving cable ampacity ratings, voltage ratings, and Class 1E separation criteria. We are reporting this issue under the provisions of 10CFR50.55(e).
The required information follows.
DESCRIPTION During design validation of calculations associated with the Class 1E AC Electrical System, the following deficiencies were discovered:-
a) 11 Class IE cables exceed calculated allowable ampacities (3 distribution panel feeders, 1 lighting transformer secondary and 7 branch circuit cables).
b) 21 Class 1E circuits, consisting of 32 Class IE cables, provide less than required voltages for associated branch circuit loads.
c) 6 Class IE circuits have non-Class IE utility receptacles and/or lights included in the circuit loads, d) 17 Class 1E circuits receive source power from oversized circuit breakers, permitting the associated cables to exceed allowable ampacities.
e) 2 Class 1E cables exceed allowable ampacities according to existing circuit breaker sizes (the circuit breakers are sized correctly according to existing circuit loading).
f) A) proximately 56 Class 1E branch equipment feeder cables are undersized, t1us delivering less than required ampacities to associated loads, se01200324 880111
(
]S 4
DR ADOCK 050 9
TXX-88064 January 11, 1988 Page 2 of 2 g) Approximately 103 Class lE branch circuit breakers are inadequately sized (oversized or undersized).
h) 7 Class lE MCC feeder cables are not afforded proper protection by the feeder switchgear circuit breaker.
i) Class lE MCC XEB2-2 feeder cable is undersized.
These deficiencies are apparently due to a misapplication of cable protective device sizing, and separation criteria. These deficiencies are assumed to apply to the entire Class lE AC Electrical System.
SAFETY IMPLICAT10tlS Failure to adequately size the cables, protect the load, and failure to adequately address cable separation criteria in the original design of Class lE circuits could result in the inoperability of the affected Class 1E circuits and equipment.
This issue represents a significant final design deficiency as approved and released for construction such that the design does not meet the criteria in the FSAR.
CORRECTIVE ACT10ti The design criteria for cable sizing has been established and documented in design basis document DBD-EE-052 "Cable Philosophy and Sizing Critr.ria".
Circuit breaker design criteria has been established in Design Basis Document DBD-EE-051 "Protection Philosophy". Electrical separation design criteria has been established and documented in Design Basis Document DBD-EE-05/
"Separation Criteria."
Cables and circuit breakers will be replaced such t. hat the applicable Class lE circuits can perform intended safety functions.
The non-Class IE loads described in item (c) will be disconnected from Class IE power and reconnected to flon-Class lE power sources.
A Class lE power source will also be provided for the two Class IE loads presently powered from a lion-Class 1E lighting panel.
These actions will be completed no later than June 15, 1988.
Very truly yours, WldL W. G. Counsil WJil/grr c - Mr. R. D. Martin, Region IV Resident inspectors, CPSES (3)
_ _ - _ _ _ _ _