ML20205G020

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Interim Deficiency Rept 64 Re Uninterruptible Power Supply Assembly Defects.Initially Reported on 860708.Cracked or Stressed Fuse Blocks Will Be Replaced by Nov 1986.Final Rept Anticipated by 861201
ML20205G020
Person / Time
Site: Satsop
Issue date: 08/08/1986
From: Olson P
WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To: Kirsch D
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
64, GO3-86-40, GO3-86-440, NUDOCS 8608190383
Download: ML20205G020 (3)


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A Washington Public Power Supply System Box 1223 Eima, Washington 98541 1223 (206)482-4428 l

l August 8,1986 G03-86-440 Docket No. 50-508 1

U. S. Nuclear Regulatory Commission, Region V Office of Inspection and Enforcement 1450 Maria Lane, Suite 260 Walnut Creek, California 94596-5368 Attention: Mr. D. F. Kirsch, Acting Director Division of Reactor Safety and Projects

Subject:

NUCLEAR PROJECT NO. 3 POTENTIAL 10CFR50.55(e) DEFICIENCY UNINTERRUPTIBLE POWER SUPPLY -

ASSEMBLY DEFICIENCIES, D/N #64 On July 8, 1986, the Supply System notified your office of a potential 10CFR50.55(e) deficiency concerning the subject condition. Attached is a Supply System approved Interim Report. The report provides a description of the deficiency and corrective actions taken/ planned. Until repairs are complete, an analysis of the safety implications cannot be comaleted.

d?! A N0193ti 8i :ll lit i I 501 0861 8608190383 DR 860808 'i ADOCK 05000508 4 PDR O'JN 03fj3033 N \ \

N U. S. Nuclear Regulatory Commission, Region V G03-86-440 Attention: Mr. D. F. Kirsch, Acting Director August 8, 1986 Page Two A Final Report will be provided to your office by December 1,1986.

Should you have any questions or desire further information, please contact me directly, au . Olson Program Director, WNP-3 DRC/cae Attachment cc: Mr. J. A. Adams, NESCO Mr. R. M. Boucher, Pacific Power & Light Co.

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

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

i Mr. J. R. Lewis, BPA Mr. N. S. Reynolds, Bishop, Liberman, Cook, Purcell & Reynolds Mr. D. Smithpeter, BPA Ms. R. M. Taylor, Ebasco - Elma Mr. B. D. Withers, Portland General Electric Co.

Document Control Desk - U. S. NRC ,

l l

1 1

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

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

ASSEMBLY DEFICIENCIES (D/N #64)

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 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:

o 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.

o 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.

This circuit connects the battery to the inverter. The failure mode would only show up during a power failure when the inverter could not draw sufficient current from the battery. Thus, the inverter would shut down; a failure of the 120 Volt Vital AC.

Each of the four (4) SUPS units provide 120 Volt AC uninterruptible and regulated power to each of the four (4) channels of the plant protection system and instrumentation (Channels SA, SB, SC, and SD). Since the four (4) SUPS units are identical, the defect is ccmmon mode.

Analysis of the Safety Implications Upon implementation of the repairs, the hardware in question will be closely examined for cracks. At that time a determination of safety significance will be made.

Corrective Actions Corrective actions will involve the following:

o Replacing the fuse block, if it is cracked or stressed.

o Changing the bus bar to a flexible braid, to allow metal to metal connection l between the braid and the fuse. This will also eliminate the problem of i torquing against plastic.  !

Elgar has supplied the necessary repair kits and support documentation to accomplish the above actions and will also provide a qualified Field Service Representative for installation of the repair kits.

It is anticipated that necessary repairs will be accomplished by November 1986 and a Final Report submitted by December 1,1986.