United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #: 9603280019

The Foxboro Company

Foxboro, MA U.S.A. 02035-2099           Telephone: 508-543-8750
Telex: MCI-6817560                      Fax: 508-549-6770

7 March 1996

U.S.  Nuclear Regulatory Commission
Document Control Desk
1155 Rockville Heights
Mail Stop 0-9A1
Rockville, Maryland 02852

Attn:  Chief of the Special Inspection Branch


Per our telephone conversation yesterday (6 March 1996) with Mr. Greg
Cwalina, Mr. Robert Pettis, and Mr. Steve Alexander, enclosed is a copy
of the letter which will be mailed to seven customers in the United
States and five customers outside the United States.

Very truly yours,

Richard A. Anderson, Manager
Quality Systems and Compliance



The Foxboro Company

Foxboro, MA U.S.A. 02035-2099                Telephone: 508-543-8750
Telex: MCI-6817560                           Fax: 508-549-6770

March  , 1996

ABC Utilities
P.O. Box
ABC Nuclear Power Generating Station
ABC, State Zip

Attention: Utility VP, Nuclear Operations

Dear Mr     :
Reference: Foxboro Sales Order No. 92F-XXXXX y/
           Customer Purchase Order No. bXXXX
           Model N-82Z        Transmitter

In compliance with 10CFR Part 21.21C this letter is to inform you of a
potential failure with N-820 Series transmitters with analog output as
referenced above.  The N-820 Series transmitters have electronics modules
which may have a potential to fail if exposed to high ambient thermal
cycles during the transmitter application.  Plated pins within the module
which are used as the transmitter sensor connections have the potential
to experience delamination of the plating.  As delamination occurs the
connection impedance changes, whereby the transmitter current output will
shift 0.2% and/or become intermittent or fail.  Intermittent means that
the transmitter output will decrease to 0% output from any output level,
downscale is always the failure direction.

To date there have been no transmitter module failures with the N-820
series model codes in any nuclear facility world wide.  The failures have
been of the 820 series commercial grade type and only in specific world
regions.  The failures have been in outdoor applications in the
MiddleEast, Southeast Asia and the US Southwest.  These regions
experience some the largest diurnal changes in the world.  Of 25,000
transmitters shipped since 1992 only 90 failures(0.36%) have been
identified recently as pin related failures.

The 820/N-820 series potted electronics modules will fail if high thermal
cycles exist in common with potting stresses present on the pins.
Modules with date codes of 9201 to 9545 have been targeted as the
potential failure units.  All pin stock was purged and a new pin process,
monitoring and quality measurements have been implemented.

This notification is to allow each user to make an assessment of their
application of the model transmitters specified above and determine their
course of action.  Transmitters with N-820..  -I or H analog model codes
and module date codes earlier than 9545 should be replaced.



Page 2

N-820 modules in stock as replacement modules should also be replaced.
The following are the N-820 Series electronics module part numbers which
should also be replaced:

     BO139FZ             BO139FY
     BO138RB             BO138RA
     BO139EZ             BO139EY
     DO135PZ             DO135PY
     DO139GM             DO139GL

Questions regarding this notification and the replacement procedure
should be directed to:

               Mr. James Keiper

Truman L. King
Director, Corporate Quality and
Product Safety



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