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NuclearPlantJournal.com Nuclear Plant Journal, July-August 2014
Research &
Development
Machine Verification
Independent verification of the
operating position of a valve or a switch
is a fundamental safety expectation
in nuclear plants. This task currently
consumes man-hours because a separate
operator must be dispatched to the
component’s location to verify that tasks
have been completed. The verifier is often
exposed to radiation, and because this
task is currently performed by a person,
human error is possible.
EPRI is working with TVA at the
Bellefonte site to test a prototype device
intended to replace the human verifier.
The prototype is a tablet computer with a
suitable camera. The device would support
a fully independent verification process
embedded in the operator’s procedure,
thereby avoiding the need to dispatch a
second person later. For example, at each
step where a valve is opened or closed
by procedure, the operator photographs
the component when he has completed
the step, thereby documenting key data
such as the exact time, place, and who
performed the task. Before allowing the
performer to proceed to the next step, the
machine verification software analyzes
the photo:
First, the software determines the
coordinates of the photo by identi-
fying the geometry of the objects in
the photo, matching the objects in the
photo to the laser-scanned 3D model
of the plant that is carried with the
device, and applying the lens charac-
teristics of the camera to back-fit/tri-
angulate to the only place the photo
could have been taken.
Second, the valve of interest in the
photo is isolated/matched from the
procedure step, and the visual field
of the photograph is analyzed to
confirm that the proper equipment ID
is being seen.
Third, the valve of interest in the
photo is compared to both open and
closed 3D models of the valve, and
the degree of matching of the photo
to each of the component models is
measured. The closest match is then
compared to a pre-determined figure
of merit, and if the match is within
a defined tolerance, the computer
declares the position of the valve to
be known.
Finally, if the known position match-
es the procedurally required position,
the computer registers the position to
be “verified.” This allows the opera-
tor to proceed to the next step.
At the current stage of development,
the software that calculates component
position resides in a personal computer;
the tablet and computer must be linked to
generate the verification. The final version
will have the analysis software, necessary
3D models, and the procedures/work
packages self-contained on a tablet device.
The embedded verification process would
be independent of the operator, other
than the fact that the operator carries the
device to the job site. When the procedure
calls for verification, the operator points
the camera in the general direction of
the component right after performing the
action. The verification is automatically
documented, or the operator is warned
that there is something amiss before he
can proceed.
Development and testing of the first
prototype, funded by EPRI’s Technology
Innovation Program, marks the start
of a multi-year effort to improve the
technology using commercial off-the-
shelf components and to extend its
applicability to a range of verifiable
components (valves, switches, etc.).
Contact: David Ziebell, telephone:
(404) 316-9823, email:
dziebell@epri.
com
.
Virtual Reality
State-of-the-art gaming technology
and virtual reality could re-shape how
industrial workers perform maintenance
tasks in the future. In late 2012, EPRI
released a first-of-its-kind virtual reality
maintenance application for air-operated
valves (AOV) that combines 3D modeling
and animations to create an environment
that mimics real-life plant conditions.
With more than 500 downloads since
its release, this new way of delivering
maintenance best practices for power
plant equipment is gaining traction.
EPRI’s Nuclear Maintenance Application
Center (NMAC) currently has several
more applications under development and
scheduled for release in 2014. Moreover,
the ability to use a mobile device to
access EPRI products is not limited to
3D applications; several web-enabled
databases, for example, are ready for
immediate member use.
The AOV app includes the basics
of AOV maintenance such as removal,
disassembly, inspection, reassembly,
bench set testing, installation and
troubleshooting. A module for diagnostics
testing is being added in 2014 that will
help mechanics, I&C technicians, and
engineers understand the importance
of diagnostic testing, select testing
equipment, and learn how to perform a
test and conduct signature analysis. The
revised AOV app will be available in June
2014 in a Windows version (3002002703)
and an Android version (3002002704).
A second application on bolting,
which will be available by year-end, is
based on two previous NMAC reports:
Bolted Joint Fundamentals (EPRI
1015336) and Assembling Gasketed,
Flanged Bolted Joints (EPRI 1015337).
This application demonstrates the
fundamentals of assembling a bolted
flange, and uses hands-on experience to
integrate craft experience on bolt torquing
for proper gasket engagement.
A third application due out this year
targets a complex component installed
at many plants: the ABB K-Line Circuit
Breaker. This breaker contains more than
1500 parts that need to be assembled in
the proper sequence and orientation in
order to operate correctly. The application
is being developed using subject matter
experts so that their knowledge can
be conveyed to the next generation of
electricians.
A fourth application will capture the
hands-on experience provided through
the Terry Turbine workshops that NMAC
has presented for many years. This app
will illustrate the range of common
maintenance activities associated with
Terry Turbines, including the proper
disassembly and reassembly of the
turbine. The application also enables
users to see the interaction of the complex
parts, which supports troubleshooting.
Contact: Rick Way, telephone: (704)
595-2679, email:
NDE Techniques
Many plants around the world have
begun moving used nuclear fuel into dry
storage facilities as their pools near capac-
ity. This transfer is most pronounced in
the United States, where almost 2000 dry
storage canisters are in use today, com-
