A practical example of Waste Transmuter use: Technetium.
Technetium (99Tc) is the most offending FF element. It is produced
in Nuclear Reactors at a rate of 843 kg and 535 TeraBc(1) / reactor.
It has a very large value of storage volume (48181 m3 / reactor).
Technetium is also soluble in water and, during its long half-life (2.11 x
105 years) if will presumably drift out of the repository into
the environment and hence into the biological circle. It is known that plants
and fresh water and marine organisms accumulate the element and, eventually,
may end up in human trough food.
Although its physiological effects have been poorly studied, we know it
is retained by the stomach, blood, saliva and, in particular by thyroid gland.
Its release in the Oceans (there are nowadays evidence of discharges arising
from the reprocessing plants of nuclear fuel) is an irreversible process on
the human time scale and its long-term effects are largely unknown.
Fortunately, Technetium is a pure isotope with a large resonant cross section
(link), leading to stable 100Ru (see table
). Therefore, for the above mentioned reasons, it should be transmuted with
the highest priority.
To evaluate the transmutation capacity of the Waste Transmuter, the transmutation
volume was filled with 270 Kg of Technetium in metallic form and finely dispersed
into the Lead. A 15~20% of transmutation rate, at normal Technetium concentration
was found at the end of one cycle. The elements can be left in place over
several cycles.
(1) TeraBc = 1012 disintegrations/ sec
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