Part 21 Report - 1996-181
ACCESSION #: 9602050070
Commonwealth Edison Company
Byron Generating Station
4450 North German Church Road
Byron, IL 61010-9794
Tel 815-234-5441
ComEd
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
Applicability
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
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A Unicom Company
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January 30, 1996
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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.
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January 30, 1996
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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
identified.
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.
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Contact
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
Sincerely,
K. L. Kofron
Station Manager
Byron Nuclear Power Station
KLK/BA/rp
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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