United States Nuclear Regulatory Commission - Protecting People and the Environment


ACCESSION #:  9702070338

                       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 #:  96-07-02    REPORT DATE:  01/31/97



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:  NO



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 one 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 an

isolated, but repetitive, failure of the Model 763 pressure

transmitters.  Barton issued a Part 21 notification on this issue and has

assumed responsibility for resolution.



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:



January 31, 1997



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 IPT 00455(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 rejection 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.



On December 13, 1996, ITT Barton issued a supplementary Part 21

notification.  In this notification Barton committed to supplying the NRC

periodic updates and to notify impacted customers consistent with the

requirements of 10CFR21.



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:



As noted in Revision 1 to this LER, SCE&G expected to receive failure

analysis results from ITT Barton by January 31, 1997.  As of this date,

ITT Barton has not completed its review of the issue, however, on

December 13, 1996, ITT Barton issued a supplementary Part 21

notification.  In this notification Barton committed to supplying the NRC

periodic updates and to notify impacted customers consistent with the

requirements of 10CFR21.



ITT Barton has requested that SCE&G return the two remaining unused Model

763 transmitters received in the same purchase lot as the failed units

for analytical testing.  Barton also intends to review their records to

identify units manufactured at the same time as the units shipped to

VCSNS, compare type of failure and/or repair performed on these sister

units, if any, in an effort to isolate the failures noted by this LER to

the units shipped to VCSNS.  Through these two parallel efforts, Barton

expects to ascertain the cause of failure and determine the process

enhancements to preclude recurrence of this type failure in future units

of this model.



No units of Model 763 transmitters from the original shipment in question

are available at VCSNS for installation in the plant.  The results of ITT

Barton's planned actions should benefit manufacturing processes for

subsequent generations of this model.  Also, should any recommended

actions for Model 763 units currently in service be provided by ITT

Barton, VCSNS will take appropriate action to address or implement, as

applicable.  SCE&G plans no further actions for this issue.



PRIOR OCCURRENCES:



None



ATTACHMENT TO 9702070338                                      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

A SCAN Company



                            January 30, 1997

                            RC-97-0027



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 2



Attached is Licensee Event Report No.  96-007, Revision 2, for the Virgil

C.  Summer Nuclear Station.  This report is submitted pursuant to the

requirements of 10CFR Part 21 and provides SCE&G's closure of this issue.



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

     L.  A.  Reyes                 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-97-0027)



*** END OF DOCUMENT ***





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