IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research

IGC
Annual Report 2007
IV.A.7. Development of Remote Inspection Devices
Poolside Spent Sub-assembly Inspection Bench for PFBR
A prototype special purpose
remote inspection bench has
been developed to carry out the
dimensional measurement /
profilometry and visual
examination of spent subassemblies
(SA) of PFBR at the
spent fuel storage pool. The
main purpose of dimensional
measurement/profilometry of
spent SA is to evaluate the
extent of irradiation-induced
deformation like bow, bulge
across the faces and elongation
of hexagonal SA wrapper and
to give a quick feedback on the
performance of the SA to the
plant operators. The inspection
bench is designed in such a
way that all moving
components excepting the
measuring probes, are kept
above the storage pool
eliminating the need for
expensive underwater
compatible components. Two
LVDTs have been used as
induction type touch trigger
probes to enable acquisition of
coordinates on the SA surfaces
by respective encoders on the
principal translational axes.
The inspection bench has
been installed and
commissioned at Engineering
Hall No.2. Preliminary testing
of the inspection bench has
been carried out on dummy
PFBR sub-assembly kept in air.
With the acquired surface
coordinates, profiles of the
cross sections along the length
of the SA have been generated
and integrated using standard
modeling software to get a 3D
wire frame model of the SA.
Special VB-based software has
been developed for aiding the
standard modeling software in
making the 3D wire frame
model by proper test data
structuring and archival. From
the wire frame model, extent of
deformations such as bulge
across the faces & corners, bow
& elongation of the SA could
be visualized and determined.
From the test results with SA in
air and subsequent
optimization of trigger
parameters and speed of the
scan axes, overall
measurement accuracy is found
to be ±0.2 mm and
repeatability is ±0.1mm.
Fig.1 Test results on dummy SA conducted in air
In order to validate the system
to evaluate bulges across the
hexagonal wrapper faces and
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