The CNRS Research Program on the Thorium cycle ... - Pacen - IN2P3

Thorium Cycle – Molten Salt Reactors June 2008
HN proportions between 7% and 27.5%. It is our opinion that such a quantity of the 232 U isotope,
whose presence is sometimes mentioned when discussing the Th- 233 U cycle characteristics with
regard to proliferation, should not generate intractable problems for the reprocessing of the liquid fuel.
IV TMSR-NM Design and <strong>The</strong>rmal-hydraulics
In the previous section, we have presented the overall specifications of the TMSR-NM
concept. Proceeding further, i.e. specifying and addressing the actual scientific and technical
challenges associated with a TMSR-NM, requires a preliminary reactor design along with a definition
of the main system components (reflectors, blanket, pipes, pumps, reactor vessel, heat exchangers
and energy conversion systems). This will help define relevant ranges for the operational parameters
(temperature and pressure gradients, fuel velocities as well as the on site chemistry needs) of the
primary and secondary circuits. This work should be completed by out-of-reactor analyses (fuel cleanup
unit and draining tank) regarding criticality and radiotoxicity issues. A preliminary design, allows
one to define a specific work plan detailing the specifications of each component and which
investigations are required to fulfil them,, the constraints imposed on these components and whether
and how they can be dealt with. In the future, assuming that no show-stopper has been identified, the
results can be incorporated into an optimized thorium-fuelled non-moderated MSR pre-conceptual
design taking into account all relevant operational parameters.
Fig.7 Sketch of a 1/4 sector of a TMSR-NM. Outside the core, the flow circulation is split into
32 angular sector units whose capacity corresponds to about 0.6m 3 .
We are now in the process of translating the schematic description of the TMSR-NM as shown
in Fig. 3 into a first drawing of a reactor in which all components are identified Fig. 7 displays a quarter
section of the reactor with 8 of the 32 angular sectors into which the fluid circulation is divided. An
iteration coupling of this design work with analyses of the nuclear energy deposition within the reactor
and the thermo-hydraulics simulations, is needed to optimize the global salt circulation and to evaluate
the temperature gradients. We expect a pre-design to be available by mid-2008. It will provide order of
magnitudes for the operational specifications for each component from which a consistent research
program on the components design and structure will be prepared.
As a matter of fact, from the schematic TMSR-NM concept alone, one can deduce some of the
basic parameters which characterize the operation of the reactor and consequently already define
some research actions. For instance, it would be interesting to investigate whether the temperature
range above the salt eutectic can be extended up to 850°C. Similarly, it is established that the
maximum salt velocities along pipes and fixed structures will range between 1 and 2 m/s. It has thus
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