ML20095K887

Final Rept of Deficiency 55-84-10 Re Loose Metallic Debris Found in Power Supplies of Nsps Panels.Initially Reported on 840403.Emphasis Given to Training Courses in Housekeeping for Future Work Involving Electronic Panels

ML20095K887
Person / Time
Site:	Clinton
Issue date:	08/17/1984
From:	Hall D ILLINOIS POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
55-84-10, U-10194, NUDOCS 8408300076
Download: ML20095K887 (4)

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ILLIN018 POWER COMPANY U 10194 CLINTON POWER STATION. P.O. BOX 678. CLINTON. ILLINOIS 61727

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August- 17, 1984

-Docket No.'50-461-Mr. James G.'Keppler Regional Administrator Region III U.S. Nuclear Regulatory. Commission 799 Roosevelt Road Glen Ellyn,. Illinois 60137

Subject:

10CFR50'.55(e) Deficiency 55-84-10 Debris in NSPS Panels

Dear Mr. Keppler:

On April 3, 1984, Illinois' Power notified Mr. F. Jablonski, NRC Region-III (Ref: IP memorandum Y-20521, dated April 3, 1984) of a potentially reportable deficiency under the provisions of 10CFR50.55(e), concerning the identification of loose debris

.found in.the power supplies of.the NSPS panels at Clinton Power Station (CPS). This initial notification was followed by one (1) interim report-(Reft IP letter U-10152, D. P. Hall to J. G.

Keppler dated May 4, 1984). Illinois Power's investigation of the above issue is complete and has determined that this issue represents a reportable deficiency under the' provisions of 10CFR50.55(e). This letter is submitted as a final report regarding this reportable deficiency.

Statement of Reportable Deficiency Various types of metallic debris were found in the NSPS power supplies and could conceivably, under certain conditions, cause an electrical fault, resulting in the loss of a power

-supply. Loss of a power supply may potentially degrade the level of redundancy within the NSPS circuits. We have reviewed-this concern for'possible' adverse impact on the safety of operation of CPS.

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iMr. Jcmes G.:Ksppler Pege 2 g - August ' 17i 1984-Background 1 Illinois Power's maintenance 1nstruc'tions'for control room

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equipment' require cleaning of panels and equipment prior to

. placing in service. . While _ performing the1 required : cleaning, maintenance 7ersonnel discovered some loose-debris in a power--

supply for the_ neutron monitoring equipment.c As a result, eight.

(8)_similar power _ supplies with perforated type enclosures for the:NSPS panels were inspected and various-ty7es of debris, consisting of small pieces of wire,. metal washers, metal chips',

Jand' pieces of plastic, were-found. The debris could have

-originated at the GE fabrication facility in San Jose, or possibly,.from work performed at CPS by the construction ,

contractor, Baldwin Associates.

Investigation Results/ Corrective Action Illinois l Power prepared and implemented an investigation plan to determine the extent of this problem at CPS. The

. investigation plan included:

1. ALreview of General Electric's (GE), Illinois Power's (IP) and Baldwin Associates' (BA) procedures ~was performed-to determine the adequacy of these procedures with respect-to the inspection and cleaning requirements for electronic equipment.

2. A review of this problem was performed with respect to the effects on other similar type equipment and perforated

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enclosures.

3. A review for adequacy of General Electric's cleaning,-

inspection, and shipping preparation procedures at the San Jose fabrication facility was performed.

4. A review of Baldwin Associates' procedures for protecting equipment during installation was performed.

All CPS work is performed in accordance with applicable IP procedures and necessary precautions are taken when performing work inside panels by ? l acing protective covers over the equipment immediately below the work area. This procedure prevents debris'from falling inside equipment cases. Illinois Power's' instructions also. provide the necessary guidance to clean instrument panels containing static sensitive devices. The i cleaning is required prior to the initial energization of vendor l supplied panels or after the performance of repair maintenance ~ R and/or. modification rework inside the instrument panels at CPS.

There are no requirements to clean inside enclosures of panel-mounted equipment except in. cases where an instrument is removed

.from the panel for maintenance in the shop.

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4Mr. Jgmes G. Keppler Page.3" =

. August'17, 1984 s

v General; Electric's~ San Jose procedures for-final inspection:

'of panel shop products-requires a-check for cleanliness: 1.e.,

bottom of panel cleaned out,' outer sides.of--panel washed down

-Detc. . The -procedures . did: not include ' or . note the detection of :

1oose debris.

, - The: power supplies; utilized-in the Neutron Monitoring System

. panels--are.very similar^to those in the-NSPS;with perforated enclosures. Investigation into this aspect of the problem' revealed'that-a failure-of a power supply.in the-Neutron Monitoring. System occurred on February- 21,~1984, after initial ~

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energization as a result of shorting due to a metal screw found

.inside the power supply : enclosure. The failed power supply was removed from the panel-for repair and other power supplies were-subsequently removed from the other neutron monitoring panels-for:

cleaning in the maintenance shop. No other loose debris was-found. Since the metal screw found in the failed power supply

' enclosure was identicalzto those used by:GE in the fabrication of-the' panels, Lit was concluded that the screw was-too;1arge to fall through the1 perforations-in the enclosure', and therefore, must have originated at the GE fabrication-facility in'-San Jose. The discovery of debris in'the Neutron Monitoring System power supplies' prompted the removal of the NSPS power supplies-for=

inspection and cleaning where more debris was found.

A review of other safety related equipment has not identified any other similar component enclosures where hidden >

debris could be a problem.

As a means of preventing future occurrences of this problem, GE has indicated they believe their procedures to be adequate, but that emphasis will be given to training courses in housekeeping for future work involving electronic panels.

Safety Implications / Significance ,

Illinois Power has determined that the existence of debris in the power supplies in all NSPS divisions represents a potential for common mode failures that are not considered in the ,

single failure analysis, and therefore, are not included in the design basis. The design basis for systems important to safety includes the appropriate combinations of the affects of normal and' accident conditions with the affects of natural phenomena, and not those that can result from manufacturing errors. It is 1111nois Power's contention that the NSPS equipment is designed x and qualified (seismically and environmentally) to provide high reliability =against failures, which could 7revent the performance of-its' intended safety functions, due to the effects of postulated design basis events.

.. - l Mr. James G. K:ppler Pago 4- ~ August 17,.1984 i l

Without the performance of a failure mode and effects analysis and/or qualitative fault tree analysis of-the debris found'in the Neutron Monitoring System power supply and all NSPS-power supplies, Illinois Power must conclude that the condition

-represents a significant safety concern which,-were it to have remained uncorrected. could have adversely affected the safe operation of CPS. On this basis, the issue is considered to be reportable under the provisions of 10CFR50.55(e).

We trust that'this final report provides you sufficient-information to perform a general assessment of this reportable deficiency and adequately describes our overall approach to resolve the problem.

Sincerely yours,

. . Hall Vice President RLC/cah(NRC) cc: NRC Resident Office, V-690 Director, Office of I&E, US NRC, Washington DC 20555 Illinois Department of Nuclear Safety INPO Records Center