IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research
IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research
IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research
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IGC<br />
<strong>Annual</strong> <strong>Report</strong> 2007<br />
of pristine sodalite, indicating<br />
that the incorporation of fission<br />
does not significantly alter its<br />
thermal expansion behaviour.<br />
products in the sodalite matrix The glass transition<br />
Fig.2 SEM micrograph of the glass-bonded sodalite<br />
temperature (T g ) of the glassbonded<br />
soadalite system (808<br />
K) was found to be significantly<br />
lower than that of the<br />
boroaluminosilicate glass (868<br />
K) used as the binder. This<br />
appears to be the indication of<br />
some interaction between the<br />
ceramic phase and the glass,<br />
the exact nature of which is to<br />
be established. With the glass<br />
composition employed in this<br />
study, the waste loading per<br />
canister has to be such that its<br />
centre line temperature stays<br />
well below the glass transition<br />
temperature of 808 K.<br />
IV.C.5. Development of NDE Technique <strong>for</strong> Detection of<br />
Sodium Voids in Metallic Fuels - a Simulation Study<br />
Non-destructive evaluation<br />
(NDE) plays a vital role <strong>for</strong><br />
ensuring stringent quality<br />
assurance of nuclear fuel<br />
cladding tubes. Eddy current<br />
(EC) NDE technique is routinely<br />
employed<br />
during<br />
manufacturing stages of<br />
cladding tubes of fast reactors<br />
as it is a versatile, high-speed<br />
and high-sensitive technique.<br />
Clad<br />
Al tube<br />
Notch<br />
simulating<br />
void<br />
Fig.1 Aluminum tube with machined<br />
notches simulating voids in sodium<br />
and the experimental set up <strong>for</strong><br />
imaging voids in sodium bonding.<br />
This technique is also used<br />
during post-irradiation<br />
examination of fuel pins in hot<br />
cells to detect and size surface<br />
and sub-surface defects in the<br />
cladding wall as well as certain<br />
anomalies in encapsulated fuel<br />
pellets. Metallic fuels are<br />
candidate fuels <strong>for</strong> fast breeder<br />
reactors <strong>for</strong> generation of<br />
nuclear power in future. The<br />
metallic fuel slugs in this type of<br />
fuels are encapsulated in<br />
cladding tubes with sodium<br />
bonding.<br />
During fabrication stages,<br />
there exists a possibility <strong>for</strong><br />
<strong>for</strong>mation of voids filled with<br />
inert gas due to improper<br />
sodium filling. Non-destructive<br />
detection of these voids or inert<br />
gas bubbles in sodium is<br />
important as their presence<br />
affect the heat transfer and<br />
thereby the fuel centre<br />
temperature and burn-up. From<br />
the design considerations, it is<br />
required that voids larger than<br />
1.4x2.1 mm 2 be detected<br />
during manufacturing stages of<br />
the fuel pins. In this direction,<br />
eddy current technique has<br />
been attempted to detect voids<br />
smaller than the specified size,<br />
using a pancake type probe,<br />
subsequent to initial studies on<br />
quartz tubes filled with sodium<br />
110 FUEL CYCLE
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