United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #: 9602050070

Commonwealth Edison Company

Byron Generating Station

4450 North German Church Road

Byron, IL 61010-9794

Tel 815-234-5441


January 30, 1996

LTR:      BYRON 96-0023

FILE:     2.01.0703

U. S. Nuclear Regulatory Commission

Washington, DC 20555

Attention: Document Control Desk

Subject:  Byron Station Units 1 and 2

          Braidwood Station Units 1 and 2

          10 CFR Part 21 Notification

          Intermittent Failure of Diesel Generator Relay

          NRC Dockets 50-454 and 50-455

          NRC Dockets 50-456 and 50-457


This notification is submitted in accordance with the requirements of 10

CFR Part 21, Section 21.21(b), 21.3a(3), and 21.3d(4).

Identification of Facilities and Components

Byron Nuclear Generating Station Units 1 and 2

Braidwood Nuclear Generating Station Units 1 and 2

130 Diesel Generator Electrical Relays procured from Amerace Corporation

Part #: EGPDRC2017003, date coded #9245

Identification of Component Manufacturer/Supplier

Amerace Electronic Components

7474 Utilities Road

Punta Gorda, Florida 33982


     A Unicom Company

Byron Ltr: 96-0023

January 30, 1996

Page 2

Nature of Defect

The defect is related to an incomplete solder process on the coil

termination to the transient suppression assembly board on the subject

relays.  The relays were manufactured by Amerace and provided specific to

ComEd.  The defective relay consists of a nuclear dedicated relay "EGPD"

with the commercial "R" option.  The commercial grade option is an add-on

board to the relay which consists of an internal diode which suppresses a

coil deenergization transient.  The defective solder joint occurred at

the interface between the relay and the add-on board.  These relays were

provided to ComEd for use as replacement parts in the Emergency Diesel

Generator (D/G) local control panels at ComEd's nuclear stations.

On November 16, 1995, an attempt was made to start the 1A D/G at Byron

Station.  The 1A D/G started; however, the D/G did not come up to full

speed.  The D/G then shutdown with no trip indications.  A second start

attempt was performed and the D/G started and operated normally.  An

investigation determined that a relay in the D/G local control panel was

intermittently failing to energize.  This intermittent failure was the

apparent cause of the D/G to come up to full speed.  The suspect relay

was replaced and the 1A D/G ran normally after the relay replacement.

The failed relay and two (2) previously replaced relays from the same

date code (#9245) were sent to ComEd's System Material Analysis

Department (SMAD) for evaluation.  SMAD subsequently determined that two

(2) of the three (3) analyzed relays were intermittently failing due to a

cold solder joint.  ComEd determined that all relays from the date code,

#9245, were potentially suspect.  All relays from the suspect date code

were confirmed to be installed only at Byron and Braidwood Stations.

Subsequent testing performed by ComEd on the suspect relays from the 9245

date code has revealed that approximately 50% of the relays were

improperly soldered and subject to the intermittent failure mechanism.

Time of Discovery

The failure of the 1A D/G during its surveillance run occurred on

11/16/95.  ComEd determined that the failure was a potential defect

subject to the provisions of 10CFR21 on 12/5/95.  Final determination

that the defect was reportable per 10CFR21 was made on 1/26/96.

Number and Location of All Defective Components:

Per the vendor, date code #9245 for part # EGPDRC2017003 consisted of 130

relays, all of which were provided to ComEd.  Of the 130 relays in lot

#9245, 100 were installed at Byron Station and 21 were installed at

Braidwood Station at the time of the interrupted surveillance run on the

Byron 1A D/G on 11/16/95.


Byron Ltr: 96-0023

January 30, 1996

Page 3

Corrective Actions:

Immediately upon identification that the entire #9245 date code of relays

was suspect, ComEd initiated replacement activities at Byron and

Braidwood Stations.  All suspect relays at Byron and Braidwood Stations

have been identified and replaced with fully qualified relays.  Note that

some relays from date code #9245 were removed from their respective D/G

control panels and subsequently reinstalled after shop testing was

performed to ensure that the relays were properly soldered.

Per ComEd's request, Amerace conducted an extensive investigation on the

subject relays.  Amerace's investigation included a visit by Amerace

representatives to ComEd's SMAD testing facilities.  In a 1/10/96 letter

from Amerace to ComEd, Amerace indicated that they had identified the

root cause of the defect, defined the scope of the relays affected and

taken corrective action to prevent similar occurrence.  Amerace also

indicated that no other similar failures had been identified over the

past three years for their various relay configurations.  The scope of

Amerace's review included over 18,000 relays provided to both nuclear and

non-nuclear customers.  Amerace's conclusion is that the failure is

isolated to date code #9245, all of which was provided to ComEd.  As

further justification for the conclusion that the defect is isolated to

the #9245 date code, ComEd has performed extensive testing of 37 similar

relays from another date code (#9448) and no defective relays were


In 1995, Amerace moved the assembly of the relay product line from

Control Products Corporation in Grafton, Wisconsin to Amerace's in-house

facilities in Punta Gorda, Florida.  In the 1/10/96 letter to ComEd,

Amerace indicated that their operators and QC personnel have been

counseled on the nature of this defect and have been made aware of the

need for proper soldering techniques.

10 CFR 21 Evaluation

The identified defect directly led to the interrupted surveillance run of

the 1A D/G at Byron Station on 11/16/95.  The defective faulty relay did

not lead to an incident of significant magnitude.  However, there was

potential for a more significant event in a circumstance where Emergency

AC power was needed.  Therefore, ComEd has determined that the improper

solder process on the subject relays does constitute a defect per the

requirements of 10CFR21 and is reportable to the NRC.


Byron Ltr: 96--23

January 30, 1996

Page 4


Questions pertaining to this notification should be addressed to:

Bradley J.  Adams

Site Engineering

ComEd Byron Station

4450 N.  German Church Road

Byron, Illinois 61010

(815) 234-5441 x2979


K.  L.  Kofron

Station Manager

Byron Nuclear Power Station


cc:  H.  Miller, Regional Administrator-RIII

     H.  Peterson, Senior Resident Inspector (Byron)

     C.  Phillips, Senior Resident Inspector (Braidwood)

     G.  Dick - NRR

     R.  Assa - NRR

     Office of Nuclear Facility Safety - IDNS



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