ML14134A079

Part 21 - Potential Defect in NUS-710DU Trip Unit to Produce a Valid Trip Output Signal

ML14134A079
Person / Time
Site:	Perry, Grand Gulf, Columbia, Limerick
Issue date:	05/08/2014
From:	Chermak V Curtiss-Wright Flow Control Corp, SCIENTECH
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
AVC-14-005
Download: ML14134A079 (6)

Text

pl 05/08/2014 U.S. Nuclear Regulatory Commission OperationsCenter Event Report Page I Part 21 (PAR) Event # 50096 Rep Org: SCIENTECH Notification Date I Time: 05/08/2014 14:57 (EDT)

Supplier: SCIENTECH Event Date I Time: 05/07/2014 (MDT)

Last Modification: 05/08/2014 Region: 4 Docket #:

City: IDAHO FALLS Agreement State: No County: License #:

State: ID NRC Notified by: VINCENT CHERMAK Notifications: JOHNATHAN LILLIENDAHL RIDO HQ Ops Officer: STEVE SANDIN KENNETH RIEMER R3DO Emergency Class: NON EMERGENCY JACK WHITTEN R4DO 10 CFR Section: NRR PART 21 EMAIL 21.21 (d)(3)(i) DEFECTS AND NONCOMPLIANCE PART 21 - POTENTIAL DEFECT IN NUS-710DU TRIP UNIT TO PRODUCE A VALID TRIP OUTPUT SIGNAL The following summary was provided by Curtiss-Wright Flow Control Corporation:

"In certain operating configurations, NUS-710DU Trip Units could fail to produce a valid trip output signal.

"Transistor Q8 on the referenced units uses a TO-66 package and is flush mounted on the component side of the PCB. The TO-66 package, based on JDEC drawing TO-213 does not specify the size of the glass-sealed holes in the case (collector) around the base and emitter leads. Random samples measure approximately 0.11" in diameter. The PCB includes standard 0.100" solder pads on both non-component and component sides. During manufacture, Q8 is secured using screws and nuts with leads centered in the through-holes, so no direct solder pad to case contact is possible. However, the presence of the pad on the component side could facilitate, under certain conditions, excessive solder flow, creating a close proximity, or in the extreme case bridging, between solder on the emitter or base solder pad and the Q8 case. Permanent bridging would be detected during acceptance testing. However, in at least one case, with the trip unit mounted in the trip unit chassis via an extender card, the proximity was close enough to create contact when the board was slightly flexed.

"The trip units have two modes of operation, NORM and REV, selectable by switch S2, and four operating configurations: (1) NORM mode, rising trip, energize on trip, (2) REV mode, falling trip, energize on trip, (3) NORM mode, falling trip, de-energize on trip and (4) REV mode, rising trip, de-energize on trip.

"In configuration (1), the set point is applied to the negative terminal of a comparator and the input is applied to the positive terminal. When the input rises above the set point, the output of the comparator goes to the positive rail, turning on Q7. When Q7 turns on, it pulls the base of Q8 low, causing Q8 to turn on. When Q8 turns on, the trip output goes to approximately +24V.

w 05/08/2014 U.S. Nuclear Regulatory Commission OperationsCenter Event Report Page 2 "In configuration (2), the set point is applied to the positive terminal of the comparator and the input is applied to the negative terminal. When the input drops below the set point, the output of the comparator goes to the positive rail and turns on Q8, resulting in a trip output of approximately +24V.

"In configurations (1) and (2), bridging at Q8 would cause an output trip signal.

"In configuration (3), when the input drops below the reset point, the output of the comparator goes to the negative rail, which causes Q8 to turn off. When Q8 turns off, the trip output goes to approximately zero volts.

"In configuration (4), when the input rises above the reset point, the output of the comparator goes to the negative rail and turns off Q8, de-energizing the unit output.

"In configurations (3) and (4), bridging at Q8 would prevent a valid trip signal from being generated by keeping the output at logic high.

"Plant: Limerick/Part Number: NUS-710DUOTS/Quantity: 2/Serial Numbers: 1303582, 1303583 "Plant: Limerick/Part Number: NUS-710DUOTT27000/Quantity: 6/Serial Numbers: 1304197, 1304198,1304199, 1304200,1304201,1304202 "Plant: Columbia/Part Number: NUS-710DUOTT45059/Quantity: 5/Serial Numbers: 1303632, 1303633, 1303634, 1303635,1303636 "Plant: Grand Gulf/Part Number: NUS-710DUOTT27000/Quantity: 3/Serial Numbers: 1303672, 1303673, 1303674 "Plant: Perry/Part Number: NUS-710DUOTT27000/Quantity: 33/Serial Numbers: 1304219, 1304220, 1304221, 1304222, 1304223, 1304224, 1304225,1304226,1304227,1304228,1304229,1304230,1304231, 1304232, 1304233, 1304234,1304235,1304236,1304237, 1304238, 1304239, 1304240,1304241, 1304242, 1304243, 1304244,1304245,1304246,1304247,1304248,1304249,1304250, 1304251.

"Should you have any questions regarding this matter, please contact Robert Queenan, Division Manager, Scientech/Instrumentation and Controls, at (208) 524-9311."

Inslnimentation & Controls Division RIGIdaho CU R 200 S. Woodruff Ave.

Falls, ID83401 (208) 529-1000 May 8"' 2014 Letter Number: AVC-14-005 Attn: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001

Subject:

10 CFR Part 21 Report Notification, NUS71 ODU Trip Units

Dear Sir or Madam:

The purpose of this letter is to notify the Nuclear Regulatory Commission of a defect. In certain operating configurations, NUS-7 1ODU Trip Units could fail to produce a valid trip output signal. Details of the defect are provided below.

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in 6dual AV Chermak Quality Manager Scientech, a business unit of Curtiss-Wright Flow Control Corporation 200 S Woodruff Avenue Idaho Falls, Idaho 83401 Dan Meils General Manager Scientech, a business unit of Curtiss-Wright Flow Control Corporation 29399 US Hwy 19 North, Suite 320 Clearwater, FL 33761 (it) idctiillcallon ac h :ila , 1t1 JClmmti . cmr 01 c 1)asic Cl111 0c 1.suppiliCd olwsuch (hcility Or such 3cti 1mpc )it'

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Instrumentation & Controls Division CURTISS200 S. Woodruff Ave.

WRIGHT ,

Idaho Falls, ID 83401 (208) 529-1000

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In certain operating configurations, NUS-710DU Trip Units could fail to produce a valid trip output signal.

E Glass seal around lead S Thru hole for solder fiow Transistor Q8 on the referenced units uses a TO-66 package and is flush mounted on the component side of the PCB. The TO-66 package, based on JDEC drawing TO-213 does not specify the size of the glass-sealed holes in the case (collector) around the base and emitter leads. Random samples measure approximately 0.11" in diameter.

The PCB includes standard 0.100" solder pads on both non-component and component sides. During manufacture, Q8 is secured using screws and nuts with leads centered in the through-holes, so no direct solder pad to case contact is possible. However, the presence of the pad on the component side could facilitate, under certain conditions, excessive solder flow, creating a close proximity, or in the extreme case bridging, between solder on the emitter or base solder pad and the Q8 case. Permanent bridging would be detected during acceptance testing.

However, in at least one case, with the trip unit mounted in the trip unit chassis via an extender card, the proximity was close enough to create contact when the board was slightly flexed.

The trip units have two modes of operation, NORM and REV, selectable by switch S2, and four operating configurations: (1) NORM mode, rising trip, energize on trip, (2) REV mode, falling trip, energize on trip, (3)

NORM mode, falling trip, de-energize on trip and (4) REV mode, rising trip, de-energize on trip.

In configuration (1), the set point is applied to the negative terminal of a comparator and the input is applied to the positive terminal. When the input rises above the set point, the output of the comparator goes to the positive rail, turning on Q7. When Q7 turns on, it pulls the base of Q8 low, causing Q8 to turn on. When Q8 turns on, the trip output goes to approximately +24V.

In configuration (2), the set point is applied to the positive terminal of the comparator and the input is applied to the negative terminal. When the input drops below the set point, the output of the comparator goes to the positive rail and turns on Q8, resulting in a trip output of approximately +24V.

In configurations (1) and (2), bridging at Q8 would cause an output trip signal.

In configuration (3), when the input drops below the reset point, the output of the comparator goes to the negative rail, which causes Q8 to turn off. When Q8 turns off, the trip output goes to approximately zero volts.

In configuration (4), when the input rises above the reset point, the output of the comparator goes to the negative rail and turns off Q8, de-energizing the unit output.

CURTISS - Instrumentation & Controls Division 200 S. Woodruff Ave.

WRIGHT Idaho Falls, ID 83401 (208) 529-1000 In configurations (3) and (4), bridging at Q8 would prevent a valid trip signal from being generated by keeping the output at logic high.

Submitted for evaluation 4/29/2014. The evaluation was completed on 5/7/2014 In tih ~.c 1a1 1/4nOl

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Plant Part Number Quantity Serial Numbers NUS-710DUOTS 2 1303582, 1303583 Limerick NUS-710DUOTT27000 6 1304197, 1304198, 1304199, 1304200, 1304201, 1304202 Columbia NUS-710DUOTT45059 5 1303632, 1303633, 1303634, 1303635, 1303636 Grand Gulf NUS-7 IODUOTT27000 3 1303672, 1303673, 1303674 1304219, 1304220, 1304221, 1304222, 1304223, 1304224, 1304225, 1304226, 1304227, 1304228, 1304229, 1304230, 1304231, 1304232, 1304233, Perry NUS-710DUOTT27000 33 1304234, 1304235, 1304236, 1304237, 1304238, 1304239, 1304240, 1304241, 1304242, 1304243, 1304244, 1304245, 1304246, 1304247, 1304248, 1304249, 1304250, 1304251

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1. Scientech has identified a design change that corrects the problem. The correction is to install spacers under Q8 to provide clearance from the board. The Design Change Notice was complete May 7, 2014.

2. Scientech has placed a hold on all affected in-house modules, and will incorporate the design change prior to ship.

3. Scientech will notify the plants listed per 21.21(d)(4)(vi) above, and offer to correct the affected units at Scientech's facility by close of business May 8, 2014.

CURTISSWRIGHT-Instrumentation & Controls Division 200 S. Woodruff Ave.

Idaho Falls, ID 83401 (208) 529-1000 1% iii) Any advice reiated to the defect or lhilure to comply about tlie rtcility. actli Iy. or basic Component dhat has hecin, is hci,, or will bc givei to ptrc hasers or licensees.

None.

(ix) III thC case okan1 earls site permit. the entities lo whom an Carly siic permit wa,, transte'rrcd Not applicable.

Should you have any questions regarding this matter, please contact Robert Queenan, Division Manager, Scientech/Instrumentation and Controls, at (208) 524-9311.

A Vincent Chermak, SSBB, PMP Quality Assurance Manager I&C Division Scientech, a business unit of Curtiss-Wright Flow Control Company Office (208) 524-9202 1Fax (208) 524-9238 Cc: Dan Meils Robert Queenan John McGimpsey Michael Weinstein QA File