United States Nuclear Regulatory Commission - Protecting People and the Environment


ACCESSION #:   9709230143





                                        ITT Barton

                                        900 S. Turnbull Canyon Rd.

                                        PO Box 1882

                                        City of Industry, CA 91749-1882

                                        Tel. (818) 981-2547

                                        Fax. (818) 333-7241

                                        Email: ittba/ton@fluidsittind.com





July 11, 1997



U.S. Nuclear Regulatory Commission

Operations Center

Washington, D.C. 20555





Subject: Withdrawal of Potential 10CFR21 Safety Concern.



ITT Barton had previously notified your office that a situation had been

discovered that we believed may have represented a substantial safety

hazard in some of out model 763 and 763A Gage Pressure Electronic

Transmitters.  This notification was provided in the form of Potential

10CFR21 Safety Concern in response to the 10CFR21 filed by the V.C. 

Summer Nuclear Station (Docket Number 50/395) in 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.



Based on our subsequent evaluation of this concern (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and we have formally withdrawn our Notification of the Potential 10CFR21

Safety Concern. ITT Barton now considers this issue closed.



The enclosed supplement to our 10CFR21 Notification and a copy of the

Industry Advisory letter that will be transmitted to all users of the ITT

Barton Model 763 763A Cage Pressure Electronic Transmitters Is being

provided for your records.



If you have any questions please contact Theodore Holdredge, Quality

Assurance Manager, at (818) 961-2547 Ext. 363.



Regards,



Ted Holdredge

Quality Assurance Manager

ITT Industries

ITT Barton

phone (818) 961-2547

fax   (818) 937-0418



    Check us out on IndustryNet at http://www-industry-nat/ltt.barton





                       10 CFR PART 21 NOTIFICATION

                    (Final Supplement, June 13, 1997)



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 contact 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

Based to make the connections.  While a thin layer of this intermetallic

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

intermetallic 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 experiences during

nuclear power plant design basis events.  However, after very meticulous

evaluation, we have convinced ourselves that, even under the worst

credible soldering conditions, that 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 are considered. 

This finding is consistent with the results of the seismic qualification

testing performed on these type of instruments by both ITT Barton end

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 structure integrity of the soldered wire

joint 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 can not 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

involve 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 10CFR.21 Safety

Concern, ITT Barton now considers this issue closed.



If you have any questions please contact Theodore Holdredge, Quality

Assurance Manager, at (818) 961-2547 Ext. 363.





                               ITT Barton



                        Industry Advisory Letter

                             (June 13, 1997)





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. On December 13, 1996, ITT Barton

reported, in accordance with 10 CFR 21, a situation involving soldering

induced embrittlement of strain gage lead wires as possibly representing

a potential significant safety hazard.



The ITT Barton December 13 Notification was 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.



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

use to make the connections.  While a thin layer of this intermetallic

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

intermetallic 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, event under the worst

credible soldering conditions, that 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 are considered. 

This finding is consistent with the results of the seismic qualification

testing performed on these type 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

joint 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 can not be retrofitted into existing field

units, ITT Barton, via this Industry Advisory Letter, is warning our

customers of the sensitivity of the strain gage lead wires to mechanical

damage and cautions that instrument inspections not involve 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 have

formally withdrawn our Notification of this Potential 10CFR21 Safety

Concern ITT Barton now considers this issue closed.



if you have any questions please contact Theodore, Quality Assurance

Manager, at (8818) 961-2547 Ext. 363.





(doc. NRC3)





cc:



D. Evans, General Manager ITT Barton

R. Krechmery, Director of Engineering, ITT Barton

M. Garrison, Director of Operations, ITT Barton

M. Larson, ITT Barton Nuclear & Government Product Engineering

J. Incontri, ITT Barton, Director of Marketing

S. Noji, ITT Barton Consumer Affairs.





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Page Last Reviewed/Updated Thursday, March 29, 2012