ORNL-TM-7207 - the Molten Salt Energy Technologies Web Site

60
3.3.1.4 Operational c~nstraints and uncertainties
Most of the fuel behavior described or implied above may be consid-
ered well authenticated, Several constraints and at least minor uncer-
tainties are obvious.
1. Fuel for a DMSR must be prepared from LiF containing a very high
2. The fuel mixture must be managed and maintained so that an appre-
ciable fraction of the uranium is present as UP3.
3.
Additional experiments are necessary t o establish exactly what
fraction of the uranium may be present as UFcj without deleterious chemical
reactions of the UP3 with graphite or possibly with other materials within
the primary reactor system.
4. Direct measurement of the physical and heat-transfer properties
of the BMSR fuel mixture must be made.
5. Further study of the fundamental thermodynamic properties of so-
lutes in the LiF-BeF2-ThF4-UF4 mixture are needed to ensure that basic
understanding of the chemical behavior is accurate.
3.3.2 Fission-product behavior
Fragments produced on fission of a heavy atom originate in energy
states and with i ~lsizati~n levels far from those normally considered in
chemical reactions. When the fission occurs in a well-mixed mo%ten-salt
liquid medium, these fragments must come to a steady state as comonHy
encountered chemical entities because they quicldy lose energy through
eolLisions with the medium. The valence states that these chemical spe-
cies assume are presumably defined by the requirements that (1) cation-
anion equivalence be maintained in the molten-salt medium and (2) redox
e~uilibria be established between the melt and the surface layers of the
container metals 19 9 63 9 64
he fission-product cations must satisfy the
fission-product anions plus the fluoride ions released by disappearance
* The rapid radioactive decay of many species further complicates an
already complex situation.
*