The systems and components of a nuclear power plant age with
its operation. Since a fuel-handling machine, one of the major components
of a PHWR NPP, also ages, at the end of the design life of
the NPP, the machine may be stuck to the pressure tube in front
of the PHWR Calandria. Even though the machine has a troubleshooting
measure of a manual drive mechanism at its rear side
and the workers make the machine operate normally by handling
the manual drive mechanism, it is still a difficult problem to access
the manual drive mechanism. When the machine is stuck, the NPP
is being operated so that the radiation level is extremely high and
the machine can be located at a high position of up to nine meters.
Therefore, a human worker cannot approach the mechanism and
the mechanism should be handled remotely.