exotic nuclei structure and reaction noyaux exotiques ... - IPN - IN2P3

G(t)
R(I
NoTr
R(I
Tr
)
)
R(d
R(d
NoTr
Tr
t)
)t
T
Where t is the time of the nuclear shut down [y], R
the radiotoxicity of a given mass of materials [Sv/
GWe], I is the total mass of fuel (core + cycle) [kg], d
the annual production of waste [kg/y], “No Tr” for no
transmutation and “Tr” for transmutation of minor actinides,
and T the geological time of waste repository
at which the comparison is made. This ratio represents
the gain in terms of radiotoxicity obtained by
the transmutation of minor actinides, taking into account
both cumulated waste produced and materials
inventory in the cycle.
This comparison shows that the transmutation of minor
actinides must last during centuries to be effective.
This is due to the large amount of plutonium present
in the core of the reactor and in the reprocessing
plants, that becomes a waste when nuclear power
shuts down. It should be interesting now to focus on
the more efficient ways to transmute the final inventories,
essentially made of plutonium or 233 U.
Conclusion
The MURE code is a complete tool dedicated to calculation
of reactor evolution and safety parameters,
which is now available at the NEA-OECD data bank.
Thermo-hydraulics and neutronics coupling has been
implemented for dynamical studies. MURE allows to
carry out detailed neutronic studies of standard or
innovative reactors. Using these methods a preliminary
study of a Sodium Fast Reactor using U/Pu or
Th/U cycles has been done.
A complete tool of reprocessing and refuelling has
been recently implemented. It has been used to investigate
the strategy of minor actinide reprocessing
in core for both U/Pu and Th/U cycles. Moreover, we
have proposed a way to compare the global waste
production of a given fleet at equilibrium, which takes
into account the cumulated waste production and the
whole material inventory that becomes a waste at the
end of the nuclear fleet. This comparison shows that
the impact of minor actinides transmutation is very
long to become efficient (several centuries). In this
context, the advantage of the thorium cycle has been
quantified.
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