TXX-6883, Final Deficiency Rept CP-87-86 Re Potentially Undersized Circuit Breakers in Class 1E 118-volt Ac Distribution Panels.Initially Reported on 870903.Breakers Adequate to Assure That Fault or Overload Will Not Degrade Class 1E Sys
| ML20236G074 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 10/27/1987 |
| From: | Counsil W, Woodlan D TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| CP-87-86, TXX-6883, NUDOCS 8711020401 | |
| Download: ML20236G074 (1) | |
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Log # TXX-6883
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File # 10110
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908<3 Ref. # 10CFR50.55(e) 7UELECTR/C
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1 October 27, 1987 l
wunam c. counsu Decu,ive Vice P,vsident U.-S' Nuclear Regulatory Commission Attn: Document Control Desk
' Washington, D.
C..
20555 SUBJECT': COMANCHE PEAK STEAM ELECTRIC STATION (CPSES) f DOCKET NOS. 50-445 AND 50-446 l
118 VAC CIRCUIT BREAKER SIZING SDAR: CP-87-86 (FINAL REPORT) 3 l
Gentlemen:
. On September 3,'1987, we verbally notified'your Mr. H. S. Phillips of a deficiency involving potentially undersized circuit breakers in Class IE 118 V A.C. distribution panels. During the design validation program, a calculation has been completed which indicates three branch circuit breakers in the Class l
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1E 118 V A.C. instrument bus distribution' panels may be undersized. Our last t
interim report was logged TXX-6802, dated October 5, 1987. After.further
- evaluation we have determined that this item is not reportable.under the provisions of 10CFR50.55(e). This is our final report on this' issue.
Further investigation has revealed that thesel breakers.(three branch circuit breakers located in Class 1E 118 V A.C. instrument distribution panels IPC1, IPC2 and IPC4) are Class 1E breakers in series with a non-Class 1E breaker
' feeding'a non-Class 1E. load.
Class 1E breaker sizing includes a factor to
-l avoid nuisance tripping of vital loads, and was inadvertently omitted on these j
three breakers.
However, since these breakers are feeding non-Class 1E loads, allowance to avoid nuisance tripping is not necessary.
Based-on the above, the breakers, as presently sized, are-adequate to assure that a fault or overload on the non-Class 1E system will not degrade the Class j
1E system.
l Supporting documentation is available for review by your inspectors at the
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t,9 CPSES plant site.
1 Very truly yours, i
.b.
P D. R. Woodlan 1
Supervisor, Docket Licensing
[/I c - Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (3)