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Electronic Circuit...
Continued from page 45
• 64 “new” boards: 6 with tin whiskers,
20 with workmanship defects,
2 with bad components.
• 42 Train “A” boards: 1 with tin whiskers,
17 with workmanship defects, 2
with bad components.
• 46 Train “B” boards: 22 with tin
whiskers, 29 with workmanship defects.
Prior to sending the boards back to
the plant, BETA also performed baseline
scanning of each card, component by
component, for future reference to facilitate
troubleshooting and failure analysis.
Clearly, a significant impact on nuclear
safety and plant resources occurred
by identifying problems with new spares
before installation. Had some of these
cards been installed, post installation test
failures were a certainty. More importantly,
had suspect boards made it through
the post installation testing; challenges to
plant safety including plant trips would
have been possible. This is because certain
workmanship defects did not immediately
compromise the performance of
the boards but could have degraded later
resulting in latent failures.
Cost Savings Impact:
In general, the cost for in-depth, detailed
board level troubleshooting is about
half (50%) of sending it to a contracted
facility. However, savings can be much
more than that. For example, FENOC
BETA Lab was able to repair 10 obsolete
modules at a cost of $1,000 where special
order replacements from the vendor
were previously purchased at $25,000 per
module. In this example alone, $240,000
of savings was realized. Additionally, the
knowledge learned during troubleshooting
is retained within the company and
can be leveraged for use on other issues.
Overall cost savings at FENOC for
2007 were estimated to be $370,000
when compared to outside vendors. Not
included in this estimate are hard to
quantify savings due to shortened plant
outage time and avoidance of plant or
equipment outages.
Extending the life of obsolete boards
also contributes to cost savings by providing
an interim solution until replacement
technology is obtained.
Innovation:
Commercially available technology
that is usually used by manufacturers to
perform quality control checks on boards
is used to validate spare board condition.
The device is automated and measures
electrical parameters for a predetermined
set of test points on the board. This same
device is also used to scan a suspect board
during troubleshooting to identify potential
problem components.
This approach is above and beyond
the traditional hands-on techniques used at
plants and can speed up the troubleshooting
process significantly by quickly pointing
technicians to the problem area. Traditional
hands-on techniques are then used
to confirm the faulty components. Because
this automated device can quickly scan tens
or even hundreds of test points on a circuit
board, the power of automation is leveraged.
Likewise, spares can be scanned prior
to installation in the plant to prevent post
installation problems and unnecessary
rework.
Also, a commercially available software
package is used to automate troubleshooting
and testing. This package allows
multiple inputs (voltage, current, switching)
to be applied to the boards while simultaneously
measuring outputs. The package goes
beyond standard data acquisition system
since inputs can be programmed to vary in
a specific manner. The package also allows
emulation of many control functions and
final devices like valves.
The above mentioned technology
is applied in a way that allows quick but
highly detailed troubleshooting coupled
with automation of testing. Large populations
of similar boards can be validated or
troubleshot in a way that was previously
not cost effective.
Productivity/Efficiency:
Several efficiency improvements
result from this approach.
a) The approach minimizes the time
required for critical troubleshooting
b)
c)
d)
activities because the entire process
is under the control of the utility. Delays
associated with external vendors
are eliminated.
The demands on the utility’s supply
chain are reduced since there is usually
no need to search for a suitable
vendor, process a purchase order,
etc.
The plant’s technical staff is relieved
of the burden to perform these activities,
allowing them to concentrate on
other plant issues.
The utility’s work management pro-
cess (i.e. SAP) can be used to schedule
and track the work items. For
example, validation of some critical
spares needed for an upcoming refueling
outage could be scheduled for
assessment via the normal planning
process, to meet parts availability
milestones.
As mentioned elsewhere, this auto-
mated device can quickly scan spares
prior to installation in the plant to
prevent post installation problems
and unnecessary rework
e)
Transferability:
Any plant or utility could implement
this approach by assembling the applicable
staff and technology. All technology
is commercially available and can
be readily purchased for use. The necessary
skills are typically available within a
nuclear organization’s staff and it is only
a matter of building the staff and technology
into an organization that fits the utility's
structure.
In FENOC’s model, BETA Lab
serves as the central location for circuit
board issues. A dedicated staff with specific
skills complements each other to
deliver fast, efficient and accurate information.
Contact: James Amundsen,
FirstEnergy Nuclear Operating Company/
BETA Laboratory, 6670 Beta Drive,
Mayfi eld Village, OH 44143; telephone:
(440) 604-9894, fax: (440) 604-9800,
email: jpamundsen@fi rstenergycorp.
com.
46 www.nuclearplantjournal.com Nuclear Plant Journal, May-June 2009