ML20097A826

Interim Part 21 & Deficiency Rept 116 Re Failure of Static Uninterruptible Power Supply Inverters.Initially Reported on 840726.All 72 Capacitors Replaced W/Newly Qualified Capacitors (Style 020 139)

ML20097A826
Person / Time
Site:	Waterford
Issue date:	08/28/1984
From:	Gerrets T LOUISIANA POWER & LIGHT CO.
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
REF-PT21-84-520-000 116, PT21-84-520, PT21-84-520-000, W3K84-2013, NUDOCS 8409130408
Download: ML20097A826 (3)

Text

7 4

I Louisiama P O W E R & LIG H T/Waterford 3 SES/P. O. Box B/Killona, LA 70066 EuS$drsE August 28, 1984 W3K84-2013 Q-3-A35.07.I16 3  %

Mr. John T. Collins Regional Administrator, Region IV lt))4!@Di0V1Di i[ g gg U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 _

j Arlington, Texas 76012

REFERENCE:

Telecon C. Hooper (LP&L) and R. Mullikin (NRC IV) on July 26, 1984

SUBJECT:

Waterford SES Unit No. 3 Docket No. 50-382 Significant Construction Deficiency No. 116

" Failure of Static Uninterruptable Power Supply (SUPS) Inverters" First Interim Report In accordance with the requirements of 10CFR50.55(e), we are hereby providing two copies of the Interim Report of Significant Construction Deficiency No.

116, " Failure of Static Uninterruptable Power Supply (SUPS) Inverters." This item was previously identified as PRD No. 176.

Very truly yours.

Ytf Jn1&Y T. F. Gerrets Corporate Quality Assurance Manager TFG:CNH:VBR Attachment cc: Director Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D.C. 20555 (15 copies)

(

8409130408 840828 PDR ADOCK 05000 S

l

g

.o i

Mr. John T.JCollins August 28, 1984 W3K84-2013 Page 2-cc: Director

-Office of Management Information and Program Control U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. E. L. Blake Shaw, Pittman,'Potts & Trowbridge 1800 M. Street, N.W.

Washington, D.C. 20036 Mr. W. M. Stevenson Monroe & Lemann 1424 Whitney Building New Orleans, Louisiana 70130 Records Center Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, Ceorgia 30339 Mr. W. A. Cross

-7910 Woodmont Avenue Suite 1200 Bethesda, Maryland 20814

g,

/

.~% :

FIRST< INTERIM REPORT SIGNIFICANT CONSTRUCTION DEFICIENCY NO. 116

" FAILURE OF STATIC UNINTERRUPTABLE POWER SUPPLY (SUPS) INVERTERS" INTRODUCTION This. report is submitted pursuant to 10CFR50.55(e). .It describes a problem associated with the Static Uninterruptable Power Supply. (SUPS), namely, capacitor failures in the inverter output at. the Constant Voltage Transformer (CVT). 'It also describes subsequent corrective actions-taken on the SUPS unit to preclude recurrence.

This has not been-reported to th'e USNRC pursuant to 10CFR21.

DESCRIPTION Waterford 3 had recently experienced numerous inadvertent trips of the safety related & non-safety related SUPS units which resulted in an investigation to determine the cause of the. trips. A total of seven (7) failed capacitors.were identified of which six (6) were found in~the following class 1E inverters:

SUPS .3MA-S, 3MB-S, and 3MD-S containing one (1), two (2), and three (3) -failed capacitors, respectively. Additional problems have been experienced with setpoints on all AC and DC voltage sensing boards. The cause of capacitor-failures is not conclusive, however, discussions with Solid State Controls-Incorp.~ (SCI) have indicated that these failures are not unique to Waterford

3. We have transmitted four (4) failed and one (1) good capacitors for their evaluation of the cause of the failure as well as a request to' examine whether-or not this is a generic concern. All the capacitors supplied by SCI have identification' code CDE KBXK1056PI, style 020138, and date coded 8139.

SAFETY IMPLICATIONS If left uncorrected, a common-mode failure of the SUPS units due to failed CVT capacitors can result in the loss of power to all safety related buses, thereby compromising the capability to assure the safe operation of the plant.

CORRECTIVE ACTIONS All capacitors (72) have been replaced with a newly qualified capacitor (style 020 139). - Additionally, all AC-DC sensing boards have been replaced.

-Maintenance procedures have been revised for procedurally setting setpoints as well as the numerical value of the setpoints. FSAR commitments such as voltage regulation verification and response to transient conditione have been retested. No trips have occurred since replacement of capacitors and sensing.

i. boards. Test data is currently undergoing final review. Project Engineering

, in concert with SCI are sti'l attempting to determine cause of capacitor failure.-

An update or Final Repvrt vill be submitted to the USNRC on or before

September 30, 1984.

u - _ _

1