Part 21 Report - 1997-121
LICENSEE: ITT INDUSTRIES
SITE: ITT INDUSTRIES EN NUMBER:32612
DOCKET: EVENT DATE: 07-11-97
RX TYPE: EVENT TIME: 12:00
VENDORS: NOTIFY DATE: 07-11-97
EMERGENCY CLASS: N/A REGION: 4 STATE: CA TIME: 17:45
OPS OFFICER: JOHN MacKINNON
10 CFR SECTION: CDEG 21.21(c)(3)(i) DEFECTS/NONCOMPLIANCE
WITHDRAWAL OF POTENTIAL 10 CFR PART 21 SAFETY CONCERN
THE ORIGINAL 10 CFR PART 21 NOTIFICATION CAN BE FOUND IN EN
31570. HOWEVER, THE FINAL SUPPLEMENT TO THE ITT BARTON 10 CFR
PART 21 NOTIFICATION IS PROVIDED IN DETAIL.
THE FOLLOWING TEXT IS FROM A FACSIMILE SUBMITTED BY ITT:
"THIS NOTIFICATION IS PROVIDED AS SUPPLEMENTARY INFORMATION TO
THE 10 CFR PART 21 NOTIFICATION FILED BY THE V. C. SUMMER NUCLEAR
STATION (DOCKET NUMBER 50/395) IN THEIR LICENSING EVENT REPORT
(LER) NUMBER 96-007, REV. 2,
SUBMITTED TO THE U.S. NUCLEAR REGULATORY COMMISSION BY SOUTH
CAROLINA ELECTRIC AND GAS LETTER NUMBER RC-97-0027 DATED JANUARY
30, 1997, AND ITT BARTON SUPPLEMENTARY INFORMATION ON THIS ISSUE
DATED DECEMBER 13, 1996."
"ITT BARTON SUPPLIES MODEL 763 AND 763A GAGE PRESSURE ELECTRONIC
TRANSMITTERS TO THE COMMERCIAL NUCLEAR POWER INDUSTRY AS BASIC
COMPONENTS FOR USE IN SAFETY-RELATED APPLICATIONS. WE PREVIOUSLY
REPORTED (DECEMBER 13, 1996) A SITUATION INVOLVING SOLDERING
INDUCED EMBRITTLEMENT OF STRAIN GAGE LEAD WIRES AS POSSIBLY
REPRESENTING A POTENTIAL SIGNIFICANT SAFETY HAZARD."
"THE WIRE EMBRITTLEMENT OCCURS DURING THE SOLDERING OF THE 10
STRAND #40AWG COPPER LEADS THAT CONNECT THE VARIABLE RESISTANCE
STRAIN GAGES TO THE REMAINDER OF THE ELECTRONIC CIRCUIT. THIS
EMBRITTLEMENT INVOLVES A METALLURGICAL REACTION BETWEEN THE
COPPER WIRE AND THE TIN BASED SOLDER USED TO MAKE THE
CONNECTIONS. WHILE A THIN LAYER OF THIS INTER-METALLIC COMPOUND
IS NATURALLY PRODUCED DURING THE METALLURGICAL BONDING PROCESS,
AS THE THICKNESS OF THE LAYER INCREASES, COPPER IS CONSUMED, AND
THE MECHANICAL INTEGRITY OF THE JOINT IS REDUCED. THE DYNAMICS OF
THE INTER-METALLIC MATERIAL GROWTH ARE INFLUENCED BY A NUMBER OF
FACTORS WHICH INCLUDE THE AMOUNT OF TIN AND OTHER ELEMENTS IN THE
SOLDER, THE SOLDERING TEMPERATURE, AND THE DURATION OF THE HEAT
EXPOSURE."
"ITT BARTON WAS INITIALLY CONCERNED THAT INSTRUMENTS WITH
EXCESSIVE WIRE EMBRITTLEMENT MAY NOW BE IN USE FOR SAFETY-RELATED
APPLICATIONS WHICH MAY FAIL WHEN SUBJECTED TO HIGH VIBRATIONAL
STRESSES EXPERIENCED DURING NUCLEAR POWER PLANT DESIGN BASIS
EVENTS. HOWEVER, AFTER VERY METICULOUS EVALUATION, WE HAVE
CONVINCED OURSELVES THAT, EVEN UNDER THE WORST CREDIBLE SOLDERING
CONDITIONS, THE STRENGTH OF THE STRAIN GAGE LEAD WIRES HAS A
SAFETY FACTOR OF AT LEAST 200 TO 1 WHEN SEISMIC INDUCED LOADING
CONSISTENT WITH OUR 12 g SEISMIC QUALIFICATION [IS] CONSIDERED.
THIS FINDING IS CONSISTENT WITH THE RESULTS OF THE SEISMIC
QUALIFICATION TESTING PERFORMED ON THESE TYPE[S] OF INSTRUMENTS
BY BOTH ITT BARTON AND WESTINGHOUSE WHERE NOT ONE OF THE TEST
SPECIMENS WAS FOUND TO HAVE STRAIN GAGE LEAD WIRE FAILURE."
"AS A MATTER OF PRUDENCE, ITT BARTON IS IMPLEMENTING A DESIGN
CHANGE THAT WILL SUBSTANTIALLY IMPROVE THE STRUCTURAL INTEGRITY
OF THE SOLDERED WIRE JOIN AND LIMIT THE SUSCEPTIBILITY OF THE
JOINT TO MECHANICAL FATIGUE THAT MIGHT BE INDUCED BY FIELD
CALIBRATION PERSONNEL WHILE INSPECTING THE INTERNALS OF THE
INSTRUMENT. BECAUSE THIS DESIGN CHANGE CANNOT BE RETROFITTED INTO
EXISTING FIELD UNITS, ITT BARTON WILL ISSUE AN INDUSTRY ADVISORY
LETTER TO OUR CUSTOMERS WARNING THEM OF THE SENSITIVITY OF THE
WIRES TO MECHANICAL DAMAGE AND CAUTIONING THAT INSTRUMENT
INSPECTIONS NOT INVOLVED PHYSICAL CONTACT WITH THE EXPOSED STRAIN
GAGE LEAD WIRES."
"BASED ON THIS RECENT EVALUATION (DOCUMENTED IN A FORMAL
ENGINEERING REPORT AVAILABLE FOR AUDIT/REVIEW AT OUR FACILITIES),
ITT BARTON IS PLEASED TO ANNOUNCE THAT OUR CONCERNS HAVE BEEN
ALLEVIATED, AND WE FORMALLY WITHDRAW OUR NOTIFICATION OF THIS
POTENTIAL 10 CFR [PART] 21 SAFETY CONCERN. ITT BARTON NOW
CONSIDERS THIS ISSUE CLOSED."
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