Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
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and we have formally withdrawn our Notification of the Potential 10CFR21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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