Page 41 - Nuclear Plant Journal Digital Edition: January - February 2013
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Nuclear Plant Journal, January-February 2013
41
long vertical canal with a diameter of
22 inches. A special loading unit was
designed for the lowering the delivery
& installation robots into the reactor
area. This device employed mechanical
actuators that guided the cage through a
vertical column past several protruding
obstacles.
The second delivery robot (used for
entry into the field of guide tubes) was
designed with a rugged crawler track
chassis, so that it could traverse over
obstructions within the reactor internals
such as protruding bolts, jutting plate
edges, and gaps between plates.
The Installation-robot was based
on a compact wheeled platform design
equipped with a magnetic chassis, such
that it could travel along the underside
of support beams near the reactor. The
Diakont engineering team carried out 74
experiments to optimize the design of
the platform’s magnets. The resulting
robotic platform was able to maintain a
magnetic connection with up to 140 kg
(308 pounds) of weight.
After being delivered into the
reactor, the installation robot was raised
to the support beams where it adhered
magnetically to a metal I-beam on
the interior ceiling for traveling to the
guide tubes. Control of robots and the
transmission of video signal were carried
out by cable, which was pulled behind the
robots inside of reactor space. The cable
was encased in a rigid radiation-tolerant
envelope which prevented damage when
coming in contact with protruding bolts.
Once it reached the guide tube being
repaired, the installation robot utilized
an internal laser alignment system
for positioning into the appropriate
orientation. The installation robot then
opened the lengthening collar which
was kept closed until reaching the repair
position to decrease the robot’s size when
crawling between tubes. Figure 2 shows
the installation robot aligning to the fuel
guide tube with the extension collar
opened. The Diakont robot then tightened
Figure 1- Diagram of Fuel Guide Tubes
(Continued on page 42)
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