ML20207F103

Final Deficiency Rept Re Four Elgar Corp Static Uninterruptible Power Supply Units That Could Potentially Result in Failure of Class 1E 120-volt Vital Ac Bus. Condition Not Reportable Per 10CFR50.55(e)

ML20207F103
Person / Time
Site:	Satsop
Issue date:	12/18/1986
From:	Olson P WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
GO3-86-622, NUDOCS 8701050437
Download: ML20207F103 (4)

Text

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Washington Public Power Supply System ,#p m'"

Box 1223 Elma, Washington 98541-1223 (206)482-4428 k 40 December 18, 1986 G03-86-622 Docket No. 50-508 U. S. Nuclear Regulatory Commission, Region V Office of Inspection and Enforcement 1450 Maria Lane, Suite 210 Walnut Creek, California 94596-5368

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Attention: Mr. D. F. Kirsch, Acting Director Division of Reactor Safety and Projects

Subject:

NUCLEAR PROJECT NO. 3 POTENTIAL 10 CFR 50.55(E) DEFICIENCY UNINTERRUPTIBLE POWER SUPPLY-ASSEMBLY DEFICIENCIES, D/N #64

Reference:

Letter, (G03-86-440), Mr. P. D. Olson to Mr. D. F. Kirsch, same subject, dated August 8, 1986.

The referenced letter provided your office with an Interim Report for the subject condition. The report noted that the engineering evaluation of the deficiency had not been completed and, therefore, a final determination of safety significance could not be made at that time.

The engineering analysis of the deficiency has now been completed.

Based on the results of the analysis, it has been determined that the subject condition is not reportable per 10 CFR 50.55(e).

8701050437 861218 PDR ADOCK 05000508 S PDR

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U. S. Nuclear Regulatory Commission, Region 1/ December 18, 1986 Attention: Mr. D. F. Kirsch, Acting Director G03-86-622 Page Two Attached is the Supply System's approved Final Report for the subject deficiency, corrective actions taken and analysis of the safety implications.

Should you have any questions or require further information, please contact me directly.

Program Di or, WNP-3 AGC/st Attachment cc: Mr. J. A.. Adams, NESCO Mr. M. F. Barnoski, Combustion Engineering Mr. R. M. Boucher, Pacific Power & Light Co.

Mr. W. L. Bryan, Washington Water Power Co.

Mr. R. E. Dyer, Portland General Electric Co.

Mr. W. J. Finnegan, Puget Sound Power & Light Co.

Mr. J. R. Lewis, BPA Mr. N. S. Reynolds, Bishop, Liberman, Cook, Purcell & Reynolds Mr. D. Smithpeter, BPA Ms. R. M. Taylor, Ebasco - Elma Document Control Desk - U. S. NRC

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WASHINGTON NUCLEAR PROJECT NO. 3 (DCCKET NO. 50-508)

POTENTIAL 10CFR50.55(e) DEFICIENCY FINAL REPORT UNINTERRUPTIBLE POWER SUPPLY -

ASSEMBLY DEFICIENCIES (D/N #64)

-A. Description of the Deficiency Elgar Corporation notified Ebasco of assembly deficiencies associated with' the four (4) Static Uninterruptible Power Supply (SUPS) units supplied to WNP-3 per Contract 3240-52. The deficiencies could potentially result in -

failure of the the Class IE 120 Volt Vital AC Bus and involve an improper electrical connection between one pole of the DC bus bar and a fuse block.

Specifically:

1. The bus bar'is torqued against the plastic of the fuse block. If the plastic stand should crack, the connection would not handle the required power.

2. The current path from the bus bar to the fuse is through three nuts and a brass stud. Normally,. hardware is not used as a current handling conductor.

An Elgar Corporation field service representative has inspected the SUPS units for cracked fuse blocks and reworked the electrical connections so the current path is directly from the bus bar to the fuse. The fuse block inspection found all fuse blocks acceptable (none were cracked).

, B. Safety Significance Each of the four (4) SUPS units provide 120 Volt AC vital uninterruptible anc regulated power to each of the four (4) channels cf the plant protection system and instrumentation (Channels SA, SB, SC and SD).

The circuit for which the assembly deficiency is associated connects the Class IE batteries to the inverter section of the SUPS unit. Failure of this circuit along with loss of offsite power would result in loss of the 120V AC SUPS output.

A circuit failure would result if the fuse block cracked and the electrical connection failed to handle the required power (Reference Part A, Item 1).

The electrical connection configuration, although not acceptable workmanship, would not have caused circuit failure (Reference Part A, Item 2).

Elgar's inspection of the SUPS units' fuse blocks show that the fuse blocks were not cracked and that as a result electrical connections in the circuit were tight.

Therefore, since the electrical connections were capable of performing their intended function, the assembly deficiencies are not considered significant and are not reportable under 10CFR50.55(e).

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C. Corrective Action Elgar, through their field service representative, corrected the assembly deficiencies by modifying the SUPS units in accordance with Elgar ECN No.

5910. Certificates of Conformance have been received from Elgar for material and work performed.

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