ML21105A359

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Gutor Electronic LLC Final Report of Notification of Potential Defect - 10 CFR Part 21
ML21105A359
Person / Time
Site: Summer, FitzPatrick  Constellation icon.png
Issue date: 03/19/2021
From: Schu M
Gutor Electronic LLC
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML21105A359 (7)
v • d • e


Text

Gutor Life Is C)n Sc~fleider c, Electric technology Attn : NRC Document Control Desk U.S. Nuclear Regulatory Commission Washington , DC 20555-0001 USA

Gutor Life Is C!)n Sc~neider

(,' Electric technol o gy GUTOR Electronic LLC Quality Assurance Hardstrasse 74, 5430 Wettingen Switzerland E-mail: marne.schu@se.com March 19th , 2021 U.S . Nuclear Regulatory Commission Document Control Desk Washington , DC 20555-0001 Attention : Document Control Desk

Subject:

Final Report of Notification of Potential Defect - 10 CFR Part 21 Reference : Potential Defect of Basic Components (A070) controller boards of Gutor UPS systems To Whom It May Concern:

On February 12, 2021 , Gutor Electronic LLC ("Gutor") notified the NRC Operations Center by facsimile of a reportable occurrence under Title 10 of the Code of Federal Regulations ("10CFR"), Part 21 , involving an Uninterruptible Power Supply ("UPS")

behavior that could potentially cause an unintentional shutdown of the UPS, manufactured and supplied by Gutor.

The following information is provided in compliance with the notification requirements of §10CFR21 .21(d)(3)(ii) and (d)(4):

i) Name and address of the person informing the Commission:

Marne Schu Gutor Customer Satisfaction & Quality Director Gutor Electronic LLC Hardstrasse 74 5430 Wettingen Switzerland Schneider Electric Gutor Ellc1ronic LLC

~ n-14 5430 Wetlingen I Switzertalld F bone: + 41 (0) 5C 437 343-4 F*x: + 41 (0) 56 437 3-4-4-4 Page 1 of 6

Gutor Life Is C)n techn_ology II) Identification of basic component which contains the defect:*

The potential defect is contained on the safety related Printed CircuifBoard ("P.CB")

A070 controller of Gutor UPS systems.

The main tasks of the A070 PCB controller are the followings:

  • Controlling the static switches
  • . Controlling the inverter
  • Monit9ring voltage, current,* alarms
  • Communication with the front pc;1nel The controller contains a firmware-controlled Master Processing Unit ("MPU"), a central. component of the A070 PCB controller that connects to almost any other circuits on.the board. This MPU microcontroller chip is mated in the controller board r

with a Plastic Leaded Chip Carrier PLCC") socket.

iii) Identification of the flnn supplying the basic component: .

The A070 PCB controller is designed, manufactured, and supplied_ by:

Schneider Electric P1 F Administration* Building Lot1, Block5, Phase 2 PEZA Rosario Cavite Philippines.

  • The PLCC socket is designed, manufactured, and supplied by:

Ho Chien Connectors International Co No 21 L 104 An xiang Rd Xindian Dist New Taipei City Taiwan 231 The Intel MPU chip is-stored and supplied by:

HTV Conservation GmbH Robert-Bosch-Str.28 D-64625 Bensheim

.Germany

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Page 2 of6

Gutor Life Is C)n* : Scb,oeider technology_ c, Electric

. iv) Nature of the defect and the safety hazard. which is created by the .*

defect:

The potential defect is contained on the MPU chip mated with its PLCC socket.

The Master Processing Unit (MPU) with associated peripherals is essential for the overall main controller board functionality. An intentional (pressing RESET-button) or unintenti6n_al. (hardware/firmware relat~d) actuation will immediately halt the main function leading to a loss of the inverter output voltage (not* considering separate

Independent Static Bypass Switch ("ISBSD) which shall transfer to bypass sl:lpply if available).

Besides a manual RESET, the following causes can initiate a critical RESET-cycle.

of the MPU microcontroll.er:.

  • MPU microcontroller related and intemaJly created Reset Instruction caused by corrupted RAM / ROM memory data, or
  • disturbance to Address- and Data-bus due to component failure or contact issues-affecting single or multiple contributing electrical connections.

Further to Gutor Ro~t Cause Analysis investigation, the _MPU reset condition was caused by the microcontroller inte:rnal protection mechanism.

An erratic contact integrity for the MPU chip to the associated socket caused by dissolved organic residues (white stains) present in and around the *contact areas which may have already been affected by other aging effects finally caused the disfunction.

The Identified root cause can be* seen ' in a non-compliant socket quality mated .with aged MPU chips whose con~act surfaces may show irregularities.

  • The MPU chip and associated PLCC socket contact integrity and cleanness analy_sis clearly showed that critical_ deficiencies might be present, albeit they cannot b~

. revealed by a simple optical-site inspection. There is no distinct proof that undetected particles or mold irregularities may not impair correct contact force over time.

Remaining white stains on contact springs may further dissolve w_ith temperature and_

.form the critical "white filmD penetrating non-tight contact areas.

These pro,cesses seem to evolve over time (days to multiple months) but cannot be stopped with the actual plugged design with aged microcontroller's contacts, even if Schtietoer aectt1c Saler Eloartmo LLC -

f-~~74.

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Gutor Life Is C)n Schneider technology 0Electric conserved in a nitrogen environment prior to population at the board manufacturer's plant.

Some chip pins showed organic deposits, indentations, and tin- oxidation already

-when taken from the stock conservation environment. Even an improved socket design may not compensate these issues:

v) Date on which the infonnation was obtained:

On January 19th, 2021, an independent Schneider Electric laboratory reported to Gutor that the PLCC socket of non-compliant quality was mated with aged Micro Processor Unit (MPU) cl:lips installed on the (A0?0) controller boards of the Class 1E UPS.

vi) Locations. affected by the reported condition:

Table 1 (attached) lists the sites that operate with safety related A0?0 PCB controller of Class 1E UPS where 1'0 CFR Part 21 applies.

vii) Name of the_ Implementing organization and time frame -for implementing the corrective actions:

Intermediate-Upgrade with soldered MPU design Most observations related to white stains on electrical contacts and affected pin surfaces are attributed to the MPU chip/ s_ocket assembly. Its circuit integrity is vital for a secured operation.

Gutor developed a soldered MPU chip assembly for another board generation where the same Intel 80C196 microcontroller is reflow-soldered onto an adapter PCB that is connected to the controller base PCB by soldered pins (com_parable to PLCC socket connecting pins).

This upgrade option- might be considered for the controller boards of the site inverter units. However proper de-soldering of the PLCC sockets (68-pinner on a multilayer PCB) can only be done by a specialized and Gutor known certified company in Switzerland. They are also equipped with an X-ray unit capable for post i,nspection.

Such an upgrade is however not considered as a full lifetime solution bearing in mind that not all remaining potential degradation effects related to other still plugged devices are addressed. Gutor therefore only recommends it as an intermediate solution.

Schneloor Electric

-Gat,;>r~LLC Jlmll!am 72-?4 6100 W!lllr,ae,, I ~

Pbo!No:+41 (O)Sl4!7 M34 Ftt + 4) (0) ell -tli3444 Page 4 of6

Gutor Life ls.C)n Sc~raeider technology c, Electric Upgrade to new Controller. Generation The inverter controller boards used for this_ scope of delivery are becoming obsolete

  • because of single source components which are no. longer available and where suitable*substitution components do not exist at all.

Gutor. has* developed a ~ew generation of _UPS (Inverter and Rectifier) controllers called "Blackbird" .. They have been introduced for non-nuclear applications in 2014.

and the latest evolution is now about to *complete* the demanding and stringent qualifications for Class 1E usage. Gutor is therefore proposing an upgrade* to this

. level (backwards compatibility is secured).

  • viii) Advice related to the defect that will be given to the purchasers:

Due to the multiple factors noticed during the HCA investigation, Gutor is currently

  • riot able to evaluate _if this potential failure on the A070 PCB controller could cause a substantial .

safety hazard at the impacted nuclear power plants.

In ~his concern, Gutor will contact within fwe (5) working days from issuance of this letter, the concerned Purchasers listed in Table 1.

If you have any questions or need *additional _information conceming*this .report, please do not he_sitate to contact *the undersigned at (41)-79-417-2803 or mame.sc_hu@se.com.

On behalf of. Gutor Electronic LLC, ~main at your disposal for any further clarifications.

Yours sincerely, Marne Schi -1

  • Gutor Customer Satisfaction & Quality Director

,Sclineloor Electric

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Pllooo: +*41 {D) 156 437 3434 Fax: ',.* 41 JO} _156 437 3f44

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Page 5 of 6

Gutor Life Is c:>n Scb:.11eider technology ~ Electric Table 1: List of Affected Safety Related A070 PCB Controllers within the United States Nuclear Gutor UPS system serial A070 Controller A070 Controller Purchaser Power Pl an t num ber board pa rt num ber b oard ID re ference I J .A Fitzpatrick Exelon Fitzpatrick LLC Exelon Fitzpatrick Spare part for systems 1090334001 , -002 & -003 Spare part for systems OP2447-001 ID00039148 I

J .A Fitzpatrick OP2447-001 1000065507 LLC 1090334001 , -002 & -003 I VC Summer 1 Dominion Energy South Carolina Dominion Energy 1170067001 OP2446-001 ID00062821 I

VC Summer 1 1170067002 0P2446-001 1000062822 South Carolina I VC Summer 1 Dominion Energy South Carolina Dominion Energy 1170067003 0P2446-001 ID00062823 I

VC Summer 1 1170067004 0P2446-001 1000063398 South Carolina I VC Summer 1 Dominion Energy South Carolina Dominion Energy 1170067005 Spare part for systems 0P2446-001 ID00062281 I

VC Summer 1 0P2446-001 ID00063340 South Carolina 117006700x Schneider Electric Gutor El!!otrtmic LLC tliUM!~~ n -H 5430 W~ttinge_n I Switzerland Phone: + 41 {0) 56 437 3434 Fax: + 41 (0) 56 437 3# 4 Page 6 of 6

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