IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research

IGC
Annual Report 2007
Table 2 : Results of dimensional measurements on FSA and fuel pins after154GWD/t burn-up
measured from the
reconstructed cross sections. By
assembling various crosssections
in the 3D-modelling
environment of CAM software,
the 3D wire frame model of the
FSA is reconstructed. The
magnitude and direction of the
head-to-foot misalignment,
angular twist etc., are
measured from this model.
The machine was used to
carry out metrology and
dismantling of the FBTR FSA
that was discharged after a
burn-up of 155 GWd/t. The
reconstructed cross sections of
the FSA at some typical axial
locations are shown in Fig.2.
Dimensional accuracy of these
figures lies within + 0.015mm.
The variation of flat-to-flat
distance along the length of the
FSA is shown in Fig.3. The
maximum increase in flat-to-flat
distance and corner-to-corner
distance observed are
respectively 0.7mm and
0.68mm, and they occur at the
region corresponding to the
centre of the fuel column.
Fig.4 shows the reconstructed
wire-frame model of the FSA.
The head-to-foot misalignment
of the FSA was found to be
the FSA after cutting the inner
and outer hexagonal sheaths
transversely using laser at the
7.5mm and no twist was location 605mm from the foot
observed.
end of the FSA.
Fig. 5 shows the Nd-YAG 13 selected fuel pins
laser system developed by extracted from the FSA were
RRCAT, Indore, for laser cutting. subjected to length and
The power and signal cables diameter measurements. Length
and the fibre optic cable which was measured using a
delivers the laser power at the measuring bench fitted with dial
cutting torch pass through gauges and working on
specially designed leak-tight
penetrations in the cell wall.
comparison principle with an
accuracy of ± 0.02mm. The
The DMLD machine has increase in lengths of fuel pins
additional provision for cutting
the FSA with a motorized
diamond wheel. The fuel pin
bundle was disengaged from
measured was found to vary
from 1.89mm to 4.28mm. A
fuel pin profilometer with two
linearly variable differential
Fig.2 The reconstructed cross sections of high burn-up FSA.
FUEL CYCLE 89