ML20101L275
| ML20101L275 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 12/14/1984 |
| From: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| ANPP-31466-TDS, DER-84-100, NUDOCS 8501020181 | |
| Download: ML20101L275 (4) | |
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Arizona Nuclear Power Project
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'D, O ' I P.O. BOX $2034 e PHOENIX ARIZONA 85072-2034 REGi;.:; y -
December 14, 1984 ANPP-31466-TDS/TRB U. S. Nuclear Regulatory Commission Region V 1450 Maria Lane - Suite 210 Walnut Creek, California 94596-5368 Attention: Mr. D. F. Kirsch, Acting Director Division of Reactor Safety and Projects
Subject:
Final keport - DER 84-100 A 50.55(e) Reportable Condition Relating To Compression Fittings On MCCs.
File: 84-019-026; D.4.33.2
Reference:
(A) Telephone conversation between P. Narbut and L. Spiers on December 4, 1984
Dear Sir:
Attached is our final written report of the Reportable Deficiency under 10CFR50.55(e), referenced above.
Very truly yours, f
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E. E. Van Brunt, Jr.
APS Vice President Nuclear Production ANPP Project Director EEVB/TRB/nj Attachment cc: See Page Two l
8501020181 841214 PDR ADOCK 05000528 S
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-t Mr. D. F. Kirsch DER 84-100,.
- Page Two
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Richard DeYoung, Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.
20555 T. G. Woods, Jf.
D. B. Karner W. E. Ide D. B. Fasnacht A. C. Rogers L. A. Souza D. E. Fowler T. D. Shriver C. N. Russo B. S. Kaplan J. R. Bynum J. M. Allen A. C. Gehr W. J. Stubblefield W. G. Bingham R. L. Patterson R. W. Welcher H. D. Foster D. R. Hawkinson R. P. Zimmerman L. Clyde M. Matt T..J. Bloom D. N. Stover J. D. Houchen J. E. Kirby D. Canady Records Center Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, GA 30339 b
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FINAL REPORT'. DER 84-100 DEFICIENCY EVALUATION 50.55(e),
i L ARIZONA PUBLIC SERVICE COMPANY-(APS)
PVNGS UNITS 1, 2, 3 1.
I.
Description of Deficiency
' Investigation Request (IR-031 was issued to inspect MCC power compression terminals (Cat.' Type 75B132506G701) which are mounted on split terminal blocks (Cat. Type 75B132505G701). This IR vss initiated in response to SFR #1SI-729 which questioned the security of the screws holding compression terminals to split terminal blocks. 'The investigation of Unit 2,~ Class 1E MCCs find loose holding screws on 79% of the compression type terminals. Also, at the terminal blocks, slight discoloration was noticed on some of the conductor insulation, however, the conductors themselves showed no
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signs of oxidation. The -jackets are' cut back 6-12 inches from the r
terminal ~and showed no signs of excessive heating. These McCs are manufactured and supplied by the General Electric Company (GE) and purchased by project specification 13-EM-018.
I Evaluation These loose screws can cause excessive heating at the terminal which, i
over an extended time period could oxidize the cable conductors and may cause breakage of some strands. Under extreme circumstances, this condition can cause excessive voltage drop to safety-related c
equipment thereby possibly preventing the Class 1E equipment from 3
performing its intended safety function.
The integrity of the circuits has not been degraded by the slight j
discoloration at the terminal blocks because at that location the dielectric properties of air, provided by the terminal block spacing
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- predominate. The absence of oxidation on the conductor indicates
~ they were not degraded.
The evaluation of this DER is being done on a generic basis since it is likely that different holding screws on compression terminals will require tightening in Units'1 and 3.
The root cause of loose compression terminals may be attributed to one or both of the following causes:
5 a)'.The MCCs were delivered with loose terminals and construction did not tighten them.
b) The terminals were loosened by the many terminating and de-terminating operations that occurred during construction and i
startup testing.
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Final Report DER 84-100 Page Two'
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II.
Analysis of Safety Implications Based on the fact that 79% of the compression terminals require' the tightening of their holding screws, this condition is evaluated as reportable under the requirements of 10CFR50.55(e). If this condition were to remain uncorrected, it would epresent a significant safety condition.
III.
Corrective Action a) =To preclude recurrence, Construction Specification 13-EM-306 was revised by Specification Change Notice 3789 to include the requirement,. after terminating MCC power cables, to inspect the tightness of compression terminal's holding screws and tighten them if required.
b) IR-031 has' been issued to inspect and tighten the compression j
terminal holding screws on MCCs in Units 1, 2, and 3.
Implementation ~ of IR-031 will ensure that the Class 1E terminals will'be inspected and if found loose, tightened.
c) IR-031 has been completed in Unit 1 and all compression terminal holding sc:ews for Class 1E MCCs have been tightened.
IR-031 will be completed for Units 2 and 3 prior to operating license for each unit.
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