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Part 21 (PAR) Event# 51574

Rep Org: UNITED CONTROLS INTERNATIONAL Notification Date I Time: 12/01/2015 14:53 (EST)Supplier: UNITED CONTROLS INTERNATIONAL Event Date I Time: 10/12/2015 (EST)

Last Modification: 12/01/2015

Region: 1 Docket #:City: NORCROSS Agreement State: Yes

County: License #:State: GA

NRC Notified by: ROB HALE Notifications: OMAR LOPEZ R20OHQ Ops Officer: DONALD NORWOOD HEATHER GEPEORD R4DO

Emergency Class: NON EMERGENCY PART 2 1/50.55 REACTORS EMAIL10 CFR Section:

21.21(d)(3)(i) DEFECTS AND NONCOMPLIANCE

PART 21 REPORT - IMPROPER SILVER PLATING DURING REFUBISHMENT OF AK-25 TYPE CIRCUIT

BREAKERS

The following information is a synopsis of information received via E-mail:

During refurbishment of General Electric AK-25 type circuit breakers (P/N's: AK-2A-25-1, AK-3A-25-1, and AK-7A-25-1) by United Controls International (UCI), non-currentcarrying/non-copper based components of the upper studassembly were silver plated. Bubbling of the silver plating was later noted which is an indication that the platingmaterial was not adhering to the base metal. Flaking of the silver plating material may occur and may introduceconductive foreign material into the host circuit breaker. Introduction of this conductive material could create thepossibility of a short circuit of the current sensor terminal board for circuit breakers configured with RMS-9 tripunits and subsequent failure of the circuit breaker.

Fort Calhoun Nuclear Station is the only known recipient of affected breakers. Fort Calhoun received 18 breakersthat contained improperly silver plated components. 14 of these 18 circuit breakers have been returned to UCI.Four of the 18 circuit breakers have been installed at Fort Calhoun and UCI is currently awaiting the return ofthese four circuit breakers.

UCFAX TRAN SMITTAL

DATE: December 1,2015

TO: NRC OPERATIONS FROM: Korina Looft/UCICENTER

FAX: 301-816-5151 FAX: 770-496-1422

TEL: 301-816-5100 TEL: 770-496-1406

Cc: Part 21 Notification PAGES: 12 pages with cover page

COMMENTS:I WILL FOLLOW UP AS DIRECTED TO MAKE SURE THE FAX

TRANSMITTAL WAS RECEIVED.

THANK YOU,

KORINA LOOFT

m ... ! I - ". .

UNITED CONTROLS INTERNATIONAL

December 1, 2015

U.S. Nuclear Regulatory CommissionDocument Control DeskWashington D.C. 20555-0001l

Subject: 10CFR Part 21 Notification of AK-25 Type Circuit Breakers P/N: AK-2A-25-1, AK-3A-25-1 and AK-7A-25-1 with Amptector or RMS-9 Trip Units Refurbished by United ControlsInternational (UCI)

The purpose of this letter is to provide the NRC with a report in general conformity of therequirements of I0CFR Part 21.21.

On October 12, 2015 Omaha Public Power District (OPPD) - Fort Calhoun Nuclear Stationnotified UCI that the silver plating on the arc runner components of the circuit breaker with UCIserial number 006943-07-00001 was not smooth with small bubbles (reference Figures 1 thr'u 4).The formation of bubbles in the plating material is an indication that the plating material was notproperly adhering to the base metal. Failure of the plating material to properly adhere may resultin the introduction of conductive foreign material inside the circuit breaker.

General Electric part number 269C283G2 upper stud assemblies (reference Figures 7 thru 11)are installed on each phase of the General Electric AK-25 type circuit breakers and theassemblies consist of the following components: arc runner (zinc plated carbon steel), lowerbracket (zinc plated carbon steel), stud (silver plated copper), spacer (molybdenmm), pin(molybdenum), and rivets (brass). The assembly provides a current path from the upper primarydisconnect finger assemblies to the stationary contacts. The primary disconnect finger assembliesare mounted on the stud component at the end thrtough-hole. The pin component holds thestationary contacts in place and prevents forward movement of the contacts. The arc runnercomponent helps to secure the circuit breaker arc quenchers and direct arcing cun'ent upwardsinto the arc quenchers.

During refurbishment at UCI the silver plating of the current carrying/copper based componentswere inspected for complete coverage on the components. The tupper stud was a currentcarrying/copper based component that was identified as requirng additional silver plating duringinspection. At the time of plating, the UCI inspector was unaware that the-upper stud componentwas permanently affixed to the upper stud assembly by rivets and that the upper stud assemblyconsisted of the materials identified above. During silver plating of the upper stud component theentire upper stud assembly was inadvertently plated with silver. After identification of the upperstud assembly components and the materials of the components it has become evident that silverplate does not adhere well to the materials of the non-current carrying components of the upperstud assembly and the bubbles formed in the plating material are attributed to the chemicalreaction occurring between the original zinc plating and the new silver plating.

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UNITED CONTROLS INTERNATIONAL

In response to the finding presented above, UCI has recalled all circuit breakers in which thesubject upper stud assemblies were plated with silver during refiurbishment on October 14, 2015for inspection and evaluation. Currently four circuit breakers affected by this issue are installedat the customer site and UCI is awaiting return of these items. The circuit breakers affected bythis issue were supplied to OPPD under purchase orders 00217277, 00217497, 00217657, and00208727. UCI is currently evaluating methods of removing the silver plating from the non-current carrying components of the uipper stud assembly or replacing the incorrectly plated items.As a preventative measure, UCI is evaluating methods for plating of only the upper studcomponent. UCI has implemented additional inspection criteria during the refurbishment processto avoid silver plating of non-current can'ying components.

The cause for concern in plating of silver on the non-current carrying/non-copper basedcomponents is the risk of plating •adhesion failure and possible introduction of conductive foreignmaterial into the host circuit breaker. The introduction of foreign conductive material would posethe risk of short circuiting of exposed electrical connections or binding of moving components.UCI has observed flaking and bubbling plating material on the subject silver plated non-currentcarrying components during inspection of the recalled circuit breakers. Examples of the bubblingand tlaking observed are presented in Figures 1 thru 6. The chemical reaction that occurs whensilver is plated on the originally zinc plated components is considered to have occurred withinthe roughly two month period between initial plating and current inspection. The occurrence ofbubbling plating material is not consistent throughout the plated items because the items weresand blasted prior to silver plating, to remove contaminants, which possibly removed the zincplating from some areas on the item. The silver plating on the molybdenum components (pin andspacer) appears to have flaked off, likely due to abrasion from the stationary contacts.

Based on the amount of flaking and the size of the flakes observed, UCI considers the risk ofshort circuit or binding due to flaking conductive material to be a remote possibility based on thefollowing. The components affected by the improper silver plating are enclosed within the arcquenchers of the circuit breaker and the only direction of propagation to other parts of the circuitbreaker would be by falling out thr'ough the bottom of the arc quencher. Introduction of theconductive foreign material is considered to have no effect on the stationary and moveablecontact functionality because the insulation surrounding these components does not allowcontact with any other conducting material. Because the thickness of the silver plate is so thin(0.0001" to 0.0005"), if the flaking mnaterial were to make contact between the stationary andmovable contacts during an opening event, it can be presumed that the foreign material would bevaporized due to the high curr'ent levels without any effect on the item's functionality. Note thatdue to the distance between the stationary and moveable contacts (approximately I", referenceFigure 9) when the unit is in the open state, it is highly unlikely that a flake large enough tobridge this gap would occur and if such an event did occur the flake would most likely vaporizedue to the thinness of the material. In addition, the likely-hood of binding occurring in themoveable or stationary contacts is not probable because the flaking material is so thin that themovement of either part would crumble the flakes.

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UNITED CONTROLS INTERNATIONAL

If the flaking material were somehow able to fall through the arc quenchers and moveablecontact areas, the insulation barriers present make it so that it is not possible for short circuitingof electrified component to the circuit breaker frame/ground. The only exposed electrifiedmaterial that the flakes may come in contact with below the arc quenchers are identified as beingthe current transformer studs and terminal boards (RMvS-9 configuration only, reference Figures12 thru 15), as well as the x-retay terminal block and x-relay coil terminal block (x-relay onlyinstalled on electrically operated circuit breakers, reference Figures 12, 16, 17).

The insulating barriers around the exposed current sensor studs and the spacing between adjacentcurrent sensors make short-circuiting of the exposed conducting material improbable. The "current transformer terminal boards pose the largest risk of short-circuiting because theinsulating material and spacing between adjacent terminals is small; thus, introduction ofconducting material between these terminals may cause interruption of operation of theconnected x-relay. The x-relay terminal and coil connection have sufficient insulation barriermaterial and spacing to make short-circuiting improbable.

Based on the above evaluation, the improper plating of silver on the non-current carrying/copperbased components of the upper stud assembly may represent a defective condition due to thepossibility of short-circuit of the current sensor terminal board signals for circuit breakersconfigured for RMS-9 trip unit operation.

Required informnation as per 10OCFR Part 21.21 (d)(4) follows:

(i,) Name and Address of the individual or individuals informing the CommissionRob HalePresidentUnited Controls International205 Scientific DriveNorcross, GA 30092

(ii) Identification of the facility, the activity, or the basic component supplied forsutch facility or such activity within the United States which fails to comply orcontains a defect.The items supplied to Omaha Public Power District - Fort Calhoun NuclearStation were under purchase orders 00217277, 00217497, 00217657, and00208727.

(iii) Identification of the firm constructing the facility or supplying the basiccomponent which fails to comply or contains a defect.United Controls International205 Scientific DriveNorcross, GA 30092

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UNITED CONTROLS INTERNATIONAL

(iv) Nature ofldhe defect or failure to comply and the safety hazard which is createdor could be created by such defect or failure to comply.Silver plating of the non-current carrying/non-copper based components on theupper stud assemblies of the AK-25 type circuit breaker may result in flaking ofthe silver plating material and may introduce conductive foreign material into thehost circuit breaker.Introduction of this conductive material creates the possibility of a short circuitbetween terminals of the current sensor terminal boards for circuit breakersconfigured with RMS-9 trip units. A short circuit of this terminal board may resultin failure of the connected x-relay to operate as designed and subsequent failureof the circuit breaker.

(v) The date on which the information of such defect or failure to comply wasobtained.The silver plating issue was informted by Omaha Public Power District - FortCalhoun Nuclear Station on October 12, 2015. On October 14, 2015 UCI initiateda recall of all items affected for inspection and evaluation.

(vi) in the case of a basic component which contains a defect or fails to comply, thenumber and location of these components in use at, supplied for, being suppliedfor, or may be supplied for, manufactured or being manufactured for one ormore facilities or activities subject to the regulations in this Part.

Part Number Utility P~urchase Order QuantityAK-25 Type Circuit Omaha Public 00217277 2Breaker Power District - 00217497 4w/Amptector or Fort Calhoun 00217657 7RMS-9 Trip Unit Station 00208727 5Refurbished by UCI ______________

(vii) The corrective action which has been, is being, or will be taken; the name of theindividual or organization responsible for the action; and the length of tinmethat has beeni or will be taken to complete the action.UCI is currently evaluating methods of removing the silver plating from the non-current carrying components of the upper stud assembly or replacing theincorrectly plated items. As a preventative measure, UCI is evaluating methodsfor plating of only the upper stud component. UCI has implemented additionalinspection criteria during the refurbishment process to avoid silver plating of non-current carrying components.

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UNITED CON•TROLS INTERNATIONAL

(viii) Any Advice related to thle defect or failure to comply about the facility, activity,or basic component that has been, is being, or will be given to purchasers orlicensees.This issue is isolated only to UCI refurbished items for a single customer. UCIadvises that components requiring silver plating to be clearly defined prior toimplementation.

(ix) In the case of an early site permnit, the entities to whom an early site permit was

- transferred.Not Applicable.

If" you have any questions or wish to discuss this matter or this report, please contact:

Divya PaidyEngineering Managerdpaidy@unitedcontrols.com770-496-1406 x 106

Sincerely,

Rob HalePresidentUnited Controls International

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...... ...Figure 1 (Arc Runner Front,

Bubbling Exhibited) 7 Figure 2 (Arc Runner Back,Bubbling Exhibited)

S Figure 3 (Lower Bracket Front)Figure 4 (Lower Bracket Back)

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] Exhibited) Figure 6 (Pin. Flaking Exhibited)

ArcQeQueches

Ar•.ece

Figure 7 (Assembled Circuit Breaker) Figure 8 {Assembled Circuit Breaker)

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SStationary Contacts]

in MvebleCotacts

Figure 9 (Installed Upper Stud Assemblies. Arc Quenchers Removed & Not Silver Plated)

Figure 10 (Removed Upper Stud Assembly. Front)

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Upper Stud

Figure l I (Removed Upper Stud Assembly, Side)

Current Sensors

Current Sensor

Terminal Boards

+X-Relay Terminal & CoilTerminal Blocks (Not

Visible. Behind)

Figure 12 (Assembled Circuit Breaker. Exposed Electrified Component AreasLocated Below Arc Quenchers Noted)

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{J I ( ] I ( I I III . O N [

A

Senor z[Sud

Figure 13 (Current Sensor Studs. Front)

T erminalBoards

1- igure 14t ('. urrent sensors 6: [ermineal Jzoarcls, tiottom)

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Figure 15 (Current Sensor Terminal Boards)

igure 17 (X-Relay Coil Terminal Block)

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