Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
ACCESSION #: 9610250175
LICENSEE EVENT REPORT (LER)
FACILITY NAME: Virgil C. Summer Nuclear Station PAGE: 1 OF 5
DOCKET NUMBER: 05000395
TITLE: ITT Barton Model 763 Pressure Transmitter Strain Gage
Failures
EVENT DATE: 07/30/96 LER #: 96-07-01 REPORT DATE: 10/18/96
OTHER FACILITIES INVOLVED: DOCKET NO: 05000
OPERATING MODE: 1 POWER LEVEL: 75
THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR
SECTION:
OTHER
LICENSEE CONTACT FOR THIS LER:
NAME: April R. Rice, Manager, Nuclear TELEPHONE: (803) 345-4232
Licensing & Operating Experience
COMPONENT FAILURE DESCRIPTION:
CAUSE: B SYSTEM: AB COMPONENT: MANUFACTURER: B080
REPORTABLE NPRDS: Y
SUPPLEMENTAL REPORT EXPECTED: YES EXPECTED SUBMISSION DATE: 01/31/97
ABSTRACT:
This report is being made pursuant to 10 CFR Part 21.
On June 5, 1996, engineering review of plant incident reports identified
the third failure of ITT Barton Model 763 pressure transmitters at V. C.
Summer Nuclear Station within a me week period. In each case, a strain
gage lead was broken at its terminal pin.
Model 763 transmitters are used at V. C. Summer Nuclear Station to
provide protection signals based on pressurizer pressure; specifically,
reactor trip on high pressurizer pressure or reactor trip and safety
injection on low pressurizer pressure. The transmitters exhibiting the
described defect were all from existing VCSNS stock and were received in
the same shipment. Each transmitter was calibrated, and installed as
IPT00457-RC where two failed after being in service for a short period of
time, and one failed prior to return to service. A Model 763 pressure
transmitter, of a different purchase, was calibrated and installed as
IPT00457-RC. V. C. Summer Nuclear Station ensured that the associated
application was restored to operable status. Reliability of pressurizer
pressure transmitters is verified by weekly monitoring and channel
checks.
ITT Barton has not established a root cause for what appears to be a
repetitive failure of the Model 763 pressure transmitters. Barton is in
the process of evaluating the defective V. C. Summer Model 763
transmitters for failure analysis.
END OF ABSTRACT
TEXT PAGE 2 OF 5
PLANT IDENTIFICATION:
Westinghouse - Pressurized Water Reactor
EQUIPMENT IDENTIFICATION:
Pressure transmitters used in the protection scheme circuits for
Pressurizer High Pressure Reactor Trip or Pressurizer Low Pressure
Reactor Trip and Safety Injection.
EIIS Code AB
IDENTIFICATION OF EVENT:
Potential failure of protection circuitry for Reactor Trip and Safety
Injection.
DISCOVERY DATE:
July 30, 1996 - Virgil C. Summer Nuclear Station, upon review of
failures which occurred through June 5, 1996, determined that the failure
mechanism presented a substantial safety hazard and should be reported in
accordance with 10CFR Part 21.
REPORT DATE:
October 18, 1996
This report was generated by Non-Conformance Notice 5481.
CONDITIONS PRIOR TO THE EVENT
MODE 1 75% Reactor Power
TEXT PAGE 3 OF 5
DESCRIPTION OF EVENT
On July 30, 1996, Virgil C. Summer Nuclear Station determined that a
substantial safety hazard, reportable pursuant to 10 CFR Part 21, existed
relative to the potential failure of transmitters used for pressure
protection in the Engineered Safeguards and Reactor Trip circuitry. The
devices are ITT Barton Model 763 pressure transmitters.
The Model 763 transmitters are used for providing High Pressurizer
Pressure Reactor Trip, Low Pressurizer Pressure Reactor Trip and Low
Pressurizer Pressure Safety Injection.
On June 5, 1996, a Model 763 pressure transmitter was installed at the
IPT00457-RC location and failed high prior to being placed in service.
Non-Conformance Notice 5481 was generated for evaluation of the failure.
Engineering review of plant incident reports identified this as the third
failure of a transmitter installed at this location within a one week
period. The two previous failures of Model 763 pressure transmitters at
this location failed after being in service for a short period of time
(2-5 days). Each of the transmitters installed at the IPT00457-RC
location were obtained by the same purchase order and received at VCSNS
in the same shipment.
CAUSE OF EVENT:
In each case, a strain gage lead was broken loose at its terminal pin.
This condition appears to be an inherent defect in manufacturing/repair
based on ITT Barton Failure Analysis Report FA 960701 and the number of
similar failures occurring in a short period of time.
ANALYSIS OF EVENT:
The defect could cause a loss of safety function to the extent that there
is a major reduction in the degree of protection provided to the public
health and safety. The pressurizer pressure transmitters
(IPT00455(6)(7)-RC) provide the following protection signals:
1. Reactor Trip on high pressurizer pressure.
2. Reactor Trip on low pressurizer pressure.
3. Safety Injection on low pressurizer pressure.
TEXT PAGE 4 OF 5
ANALYSIS OF EVENT: (continued)
The VCSNS FSAR takes credit for the low pressurizer pressure protection
signals to mitigate the consequences of a Large Break LOCA. A
transmitter installed at IPT00455(6)(7)-RC which fails high would not
provide the low pressure protection signal. The protection circuitry is
based on 2 out of 3 input logic, so the failure of one transmitter would
not, in and of itself, prevent the proper protection function. However,
this failure condition coincident with an additional transmitter failure
would affect the automatic activation of safety injection should a large
break LOCA occur. This could result in potential offsite exposure
exceeding 10 CFR 100.11 limits.
V. C. Summer Engineering personnel have discussed this situation with
ITT Barton. The failed transmitters were shipped and received together.
The preliminary consensus is, that a manufacturing process error
potentially contributed to the defect and this condition is an isolated
occurrence limited to the lot of transmitters from which those shipped to
VCSNS was supplied.
V. C. Summer Engineering personnel also performed a review of ITT Barton
760 model series transmitter failures using the NPRDS data base. NPRDS
indicated that most failures were either age related or unknown. There
were no strain gage failures identified; thus this review was
inconclusive as to industry experience with the problems noted for V. C.
Summer.
Other licensees with ITT Barton Model 763 pressure transmitters should
review the history for their particular applications and determine if
broken/loose strain gages have attributed to any failures which may have
occurred at their plants.
IMMEDIATE CORRECTIVE ACTIONS:
A Model 763 pressure transmitter, independent of existing VCSNS warehouse
stock, was procured and installed at the IPT00457-RC location.
V. C. Summer Station ensured that the associated applications were
restored to operable status upon identification, replacement and testing
of the respective Model 763 pressure transmitters. As the Model 763
currently installed is from an unrelated stock and is performing
satisfactorily, continued operation does not present an adverse impact on
safety.
TEXT PAGE 5 OF 5
ADDITIONAL CORRECTIVE ACTIONS:
Long term corrective actions are under evaluation and will be coordinated
with the vendor. As noted in Revision 0 to this LER, SCE&G expected to
receive failure analysis results from ITT Barton by October 18, 1996. As
of this date, ITT Barton has not completed its review of the issue.
VCSNS Engineering continues to work with the vendor on this issue. SCE&G
expects to obtain the vendor's analysis results and submit a final report
by January 31, 1997.
PRIOR OCCURRENCES:
None
ATTACHMENT TO 9610250175 PAGE 1 OF 1
South Carolina Electric & Gas Company Gary J. Taylor
P.O. Box 88 Vice President
Jenkinsville, SC 29065 Nuclear Operations
(803) 345-4344
SCE&G
October 18, 1996
RC-96-0249
Document Control Desk
U.S. Nuclear Regulatory Commission
Washington, DC 20555
Gentlemen:
Subject: VIRGIL C. SUMMER NUCLEAR STATION (VCSNS)
DOCKET NO. 50/395
OPERATING LICENSE NO. NPF-12
LER 96-007, REVISION 1
Attached is Licensee Event Report No. 96-007, Revision 1, for the Virgil
C. Summer Nuclear Station. This report is submitted pursuant to the
requirements of 10CFR Part 21 and provides an update to the initial
submittal.
Should you have questions, please call Mr. Jim Turkett at (803)
345-4047.
Very truly yours,
Gary J. Taylor
JWT/GJT/nkk
Attachment
c: J. L. Skolds K. R. Jackson
W. F. Conway D. L. Abstancce
R. R. Mahan (w/o att.) NPRDS Coordinator
R. J. White NRC Resident Inspector
S. D. Ebneter J. B. Knotts, Jr.
A. R. Johnson INPO Records Center
R. B. Clary Marsh & McLennan
S. F. Fipps NSRC
A. R. Koon RTS (LER 960007)
G. E. Williams Files (818.07, 818.18)
T. L. Matlosz DMS (RC-96-0249)
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