Nuclear Fuels :
Post Irradiation Examination
5.5
.
WIGNER ENERGY STUDIES ON
CARBON
MATERIALS
Wigner Energy in Graphite Reflector
established experimentally using differential scanning calorimetry
(DSC).
The reactor was taken to high power operation under controlled
The Wigner energy storage and release behaviour of the
cooling conditions to allow an operating temperature of 120°C
graphite reflector was evaluated after 30 years of operation.
for the graphite. The stored energy in the graphite after the
The irradiated graphite plug was sampled and subjected to
high power operation was estimated by sampling from another
graphite plug removed from the east thermal column, which
.
showed residual Wigner energy in safe levels.
Wigner Energy of Pyrocarbon Scattering
Material for AHWR
Developmental work is being carried out for obtaining noncrystalline high density pyrocarbon as the scatterer material of
AHWR with joint effort of BARC and NPL, Delhi. The pyrocarbon
material developed by BARC was characterized to obtain the
porosity and density of the compacts. The pellets prepared were
irradiated in DHRUVA reactor. Wigner energy storage
characteristics of the irradiated pellets were measured by DSC
technique. The pyrocarbon pellets showed crystallinity and storage
of considerable Wigner energy after irradiation.
Wigner Energy in CIRUS Graphite
Wigner Energy in Pyrocarbon
different annealing cycles. Graphite samples from one location,
at 305 mm from the reactor vessel end, showed that rapid
Wigner energy release during annealing is possible which could
lead to sudden temperature increase from 189°C to 290°C. The
conditions for safe annealing of the stored Wigner energy were
Nuclear Fuel Cycle
BARC HIGHLIGHTS
47