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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at our facilities), ITT Barton is pleased to announce that our concerns have been alleviated and we have formally withdrawn our Notification of the Potential 10CFR21 Safety Concern.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. *** END DOCUMENT ***