ML20099E278

Interim Deficiency Rept PRD-84/11 Re Leaking Tantalum Capacitors.Initially Reported on 840928.SA-1 Relays Will Be Returned to Westinghouse for Insp & Rework.Actions Expected to Be Completed by 850322.Final Rept Expected by 850412

ML20099E278
Person / Time
Site:	Grand Gulf
Issue date:	10/26/1984
From:	Dale L MISSISSIPPI POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
AECM-84-2-0018, AECM-84-2-18, NUDOCS 8411210210
Download: ML20099E278 (5)

Text

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.E MISSISSIPPI POWER & LIGHT COMPANY Helping Build Mississippi P. O. B OX 184 0, J AC K S ON, MIS SIS SIP PI 3 9 2 05 84 BCI 23 P l ; qc5ober 26,1984 NUCLE AR LICENSING & 1AFETY DEPARTMENT U.S. Nuclear Regulatory Commission Region 11 101 Marietta St., N.W., Suite 2900 Atlanta, Georgia 30323 Attention:

Mr. J. P. O'Reilly, Regional Administrator

SUBJECT:

Grand Culf Nucicar Station Unit 2 Docket No. 50-417 License No. NPF-13 File: 0260/L-835.0 PRD-84/11. Final Report for Unit 2 Westinghouse Type SA-1 Relays AECM-84/2-0018 On September 28, 1984, Mississippi Power & Light Company (MP&L) notified Mr. R. E. Carroll, of your office, of a Potentially Reportable Deficiency at Crand Gulf Nuclear Station (CCNS) Unit 2.

The deficiency concerns the potential for leaking tantalum capacitors, located internally at the top of the SA-1 relay printed circuit board, to cause corrosion buildup on the circuit board and subsequent relay failure.

MP&L has evaluated this deficiency for applicability to CCNS Unit 1 and determined it not reportable under the provisions of 10CFR21. Since the Unit 2 relays must be energized and monitored for two weeks (according to Westinghouse) to determine whether they contain leaking capacitors, we are unable at this time to make a determination as to whethcr the deficiency is reportabic under 10CFR50.55(o). The SA-1 relays will be returned to Westinghouse for inspection and rework (potentially defective capacitors will be replaced). Westinghouse will be requested to advise our architect engineer (Bechtel) as to the condition of the capacitors for our subsequent recommendation regnrding 10CFR50.55(e) reporting requirements.

Yours truly, L. F. Dale Director EBS/Silll: rg Attachment cc: See next page m

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'Mr. J. B. Richard s(w/a)

Mr. R. B. McGehee (w/o)

Mr. N. S. Reynolds (w/o)

Mr. G..B. Taylor (w/o)

Mr. Richard C. DeYoung. Director (w/s)

Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission i

Washington D. C.

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1. [ Description of Deficiency'

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A.. Definition'of the Problem:'

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> Westinghouse high speed differential current relays, model SA-1,

/ used for ' protection-against ;inte'real. faults on;the" emergency -

'~st on-site diesel generators.have demonstrated a generic problem:

involving tantalus (electrolytic) capacitors'. These' capacitors:

have : exhibited, in a limited number of. incidents, progressive <

. electrolyte-leakage resulting-in electrical failure.

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Name;of Plant Systems Affected:

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(2)P75t-Standby Diesel-Generator System.

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Applicability to Unit 22

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The cited condition is potentially applicable tojUnit.2.; Thiso..of report will only' address Unit 2.

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D..Part 21 Applicability:

Part 21-is not applicable to Unit 2 since this sys' tem has not been

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turned over to MP&L.

E.: Analysis of Known Safety implicationst.

The 2P75 system is comprised of two 100% redundant AC power trains; which supply emergency power to.the plant shutdown and-ESF systems which' encompasses virtually.the entire NSSS. 'Any " single failure" qu capable of. rendering either train inoperative will not create a safety problem because the remaining train.can provide' requisite AC power. No interface or interaction exists between the two trains; other:than a possible " common mode" failure..

Failure of the subject SA-1 relays could potentially trip the diese1' generator unnecessarily or allow disabling damage by an uncleared fault. Either occurrence would unnecessarily ~ prejudice successful emergency power generation.

Therefore, a potential exists for adverse effects to operational safety at any time through out the expected life time of the plant.

F.. Copy of the Part 21 Reports l

Not applicable (See item 1.D.)

G.

Statement of Applicability of this Deficiency to NSSS Vendor:

Not' applicable, based on a review of GE schematic drawings.

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III. 2 Approach"to Resoluti6n of the Probles':'

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Determine'CauseLof-the Deficiency:.

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m lit has been.well established by, various ' deficiency reports'.~f rom i j

- other' nuclear plants (e.g. Palo Verde LandiCallaway) ? and by _

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!research by the-vendor,; Westinghouse,fthat the causefis a1 bad loE..v.

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Cornell-Dubilier Company.f No tracking data exists"for;these s.

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Jaffected~ equipment.

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_B..-Determine the Extent of Deficiencyi i E'

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.The. extent:is limited to two (2),'SA-1 relays installed,in Unit 2 '

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Corrective. Actions to' Prevent Repetition's[ 4 9 '

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u This'is a a vendor'quElity control / quality? assurance problem.-

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Since the equipment has been-delivered, no~ additional'r'equirements-with regards to quality can-be. reasonably-imposed apart from.'

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vigorous. adherence to testings. schedules and methods. ~ Inithis fashionincipient'failuresmaybe;det,ectedand[ remedied.'i,, - "

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The supplier hasiupgraded th'e. suspect capacitors, which should preclude recurrence.of the cited' condition.jThe" purchase of

" future" spares,'if required. will be made from Westinghouse to ensure that upgraded items are obtained.

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Remedial Actions to Correct Existing Nonconformances:

The SA-1 relays will be-returned to Westinghouse for inspection and rework. The' supplier will replace'the~potentially'defactive-capacitors with upgraded items manufactured.to MIL SPEC M-39006.

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Westinghouse will be requested to advisefour architect engineer (Bechtel) as to the condition of the capacitors for-our subsequente recommendation regarding 50.55(e) reporting requirements.

Nonconformance Report 6814 has been written to track the replacement of SA-1 relays.

III. Status of Proposed Resolution A.

Status of Completion of I.E., II. A.',

II.B.

and II.C. :-

Items II. A, II.B., II.C. have been completed.

Item I.E.:

Need inspection results from Westinghouse.- See Item II.D.

B. ~Date when all Actions will be Completed

~.All actions are expected to be completed by March 22,-1985.

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' IV..Ra'ason Why' Final Report is Delayed-

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V The r'elays have'_to be! returned..to Westinghouse for inspection.and~

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repair..Upon completion of their' inspection.-Westinghouse lis-to

. provide the, inspection results to our-architect engineer (Bechtel) for evaluation on safety..

V.4 Date when Final-Report'wil be' Submitted-

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.A final report is expected to be provided by April'12, 1985.

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