Part 21 Report - 1997-181
ACCESSION #: 9703070020
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POWER REACTOR EVENT NUMBER: 31890
FACILITY: BYRON REGION: 3 NOTIFICATION DATE: 03/04/97
UNIT: [1] [2] [ ] STATE: IL NOTIFICATION TIME: 16:22 [ET]
RX TYPE: [1] W-4-LP, [2] W-4-LP EVENT DATE: 03/03/97
EVENT TIME: 00:00[CST]
NRC NOTIFIED BY: PAUL WENC LAST UPDATE DATE: 03/04/97
HQ OPS OFFICER: HENRY BAILEY
NOTIFICATIONS
EMERGENCY CLASS: NOT APPLICABLE
10 CFR SECTION:
CCCC 21.21 UNSPECIFIED PARAGRAPH
VERNON HODGE, RVIB NRR
UNIT SCRAM CODE RX CRIT INIT PWR INIT RX MODE CURR PWR CURR RX
MODE
1 N N 0 HOT SHUTDOWN 0 HOT SHUTDOWN
2 N Y 100 POWER OPERATION 100 POWER OPERATION
EVENT TEXT
10 CFR PART 21 NOTIFICATION - CRACKING OF VITEC TRANSFORMER CORES
THESE TRANSFORMERS ARE INSTALLED IN VARIOUS SAFETY-RELATED
CIRCUITS
BOARDS. TEMPERATURE CHANGES IN THESE CIRCUIT BOARDS COULD CAUSE
ASSOCIATED INSTRUMENTATION TO DRIFT OUT OF RANGE. THE
SAFETY-RELATED
APPLICATIONS WHERE THIS TRANSFORMER HAS THE MOST POTENTIAL IMPACT
ARE THE
DELTA TEMPERATURE PROTECTION FUNCTIONS (NRA CARDS) IN THE REACTOR
PROTECTION SYSTEM (RPS). THE DRIFT IN THE RPS COULD CAUSE A CHANNEL
TO
TRIP RESULTING IN A LOSS OF REDUNDANCY IN THE DIVERSE TRIP FUNCTION.
NOTE: THIS ISSUE ALSO APPLIES TO BRAIDWOOD UNITS 1 AND 2 AND TO ZION
UNITS 1 AND 2.
Transmittal note omitted.
Commonwealth Edison Company
Byron Generating Station
450 North German Church Road
Byron, IL (illegible)
Tel 815 (illegible)
March 3, 1997 ComEd
LTR: BYRON 97-5045
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
Zion Station Units 1 and 2
10 CFR Part 21 Notification
Cracking of VITEC Transformers
NRC Dockets 50-454 and 50-455
NRC Dockets 50-456 and 50-457
NRC Dockets 50-295 and 50-304
Reference: "Transformer Cracking", Westinghouse Potential Issue NSAL-
96-006, dated December 26, 1996.
Applicability
This notification is submitted in accordance with the requirements of 10
CFR Part 21, Section 21.21(a), 21.3a(3), and 21.3d(1).
Identification of Facilities and Components
Byron Nuclear Generating Station Units 1 and 2
Braidwood Nuclear Generating Station Units 1 and 2
Zion Nuclear Generating Station Units 1 and 2
7300 Process Protection System Integrated Circuit Cards (NRA, NLP, NSC,
NLL, NMD, NCH, NVP, and NSA applications)
NRA card model #: 2837A15G01, various date codes supplied by
Westinghouse from October 1991 through 1993.
(illegible)
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Identification of Component Manufacturer/Supplier
Westinghouse Electric Corporation
Box 355
Pittsburgh, Pennsylvania 15230-0355
Nature of Defect
During installation and testing of the RTD By-Pass modification at
Braidwood Station. a output drift observed with increasing temperature on
several RTD amplifier
Number and Location of All Defective Components
Zion Station has not identified any installations of the suspect circuit
cards at Zion. The population of potentially affected cards at Byron and
Braidwood Stations is extensive due to the number of circuit card
applications that have been identified by Westinghouse. The exact number
of potentially defective components is not currently available due to the
uncertainty of which date codes are actually installed in the plants
ComEd has determined that the applications of concern from a 10CFR21
standpoint are the NRA, NLP, and NSC cards. This is due to the isolated
output function for the applications serviced by these specific cards.
Corrective Actions:
Byron and Braidwood Stations have initiated actions to identify all
circuit cards with the affected date codes. Once the population of
impacted cards is fully identified, the affected cards will be replaced,
where appropriate. Westinghouse indicated that it is unlikely that many
transformers with cracked cores exist. In addition, it has been
determined that all installed cards are located in rooms that are
supplied by safety related, redundant HVAC systems that are designed to
maintain appropriate temperatures. The safety related applications where
this transformer issue has the most potential impact are the [symbol
omitted]T protection functions (NRA cards) because of reactor trip
concerns. These applications are subjected to periodic channel checks
and it is reasonable to assume that any significant non-conservative
calibration drift would be detectable during channel checking activities.
Both Byron and Braidwood Stations have documented operability assessments
that conclude that there is reasonable assurance of operability for the
potentially affected applications. Completion of inspection and/or
replacement of the impacted population of circuit cards for both Byron
and Braidwood Stations will be completed prior to the end of the next
refueling outage on each unit.
Byron and Braidwood Stations have inspected all spare circuit cards in
Stores to ensure that no additional potentially affected components are
placed into service.
10 CFR 21 Evaluation
The Safety related applications where this transformer issue has the most
potential impact are the [symbol omitted]T protection functions (NRA
cards). There is some potential that defective cards would not be
detected during installation and initial calibration. A negative drift
in the calibration of defective cards could result in non-conservative
calculations for both [symbol omitted]T and the corresponding setpoints.
This could result in a lack of redundant rector trip function.
Therefore, ComEd has determined that the identified defect does represent
a substantial safety hazard per the requirements of 10CFR21 and is
reportable to the NRC.
(illegible)
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Contacts
Questions pertaining to this notification should be addressed to either:
Bradley J. Adams Peter J. Wicyk
Site Engineering EI&C Engineering
ComEd Byron Station ComEd NES, ETW-III
4450 N. German Church Road 1400 Opus Place
Byron, Illinois 61010 Downers Grove, Illinois 60515
(815) 234-5441 x2979 (630) 663-7264
Sincerely,
K. L. Graesser
Site Vice President
Byron Nuclear Station
cc: H. Miller, Regional Administrator-RIII
S. Burgess, Senior Resident Inspector (Byron)
C. Phillips, Senior Resident Inspector (Braidwood)
A. Vegel, Senior Resident Inspection (Zion)
G. Dick - NRR
R. Assa - NRR
C. Shiraki - NRR
Office of Nuclear Facility Safety - IDNS
(illegible)
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