ORNL-5388 - the Molten Salt Energy Technologies Web Site

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6.2.7. Converter-Breeder System with Heavy Plutonium "Transmutation"
The preceding discussion indicates that a nuclear power system that includes an FBR
having a Pu-U core and producing 233U in a thorium blanket can maintain an energy support
ratio greater than unity while simultaneously adding 15 GWe/yr to the installed capacity
throughout the planning horizon. The possibility exists, however, that a nuclear power
system that includes an FBR having a Pu-Th core and a thorium blanket would result in a
heavy P u - ~ o - ~ transmutation ~ ~ U
rate which would maintain an energy support ratio signi-
ficantly greater than unity over the same period of time. The principal problem associated
with a nuclear system based on an FBR with a Pu-Th core is that the breeding ratio of the
breeder, and hence the breeding ratio of the entire system, tends to be low. Therefore,
the effect of adding to the system an FBR operating on denatured 233U to augment the 233U
production was also investigated. The individual reactor concepts contained in this
system are shown in Fig. 6.1-4 (Option 8).
The nuclear contribution associated with this option (Case 8L, tvith denatured
breeder) is compared to that of the LWR on the throwaway cycle for the high-cost U308
supply in Fig. 6.2-33. The system is capable of maintaining a net addition rate of
15 GWe/yr throughout the planning horizon.
The installed nuclear capacity which for Case 8L must be located in energy centers
is shown in Fig. 6.2-34 as a function of time.
out the planning horizon. The amount available for location outside the energy centers
ranges from approximately 300 GWe in the year 2000 to approximately 800 GWe in the year
2050. This can be compared to Option 6 for which the nuclear capacity that must be
located in secure regions increases continuously to approximetely 560 GWe in 2050. Thus,
a nuclear system containing FBRs with Pu-Th cores plus FBRs with denatured 233U cores is
capable of maintaining a very high energy support ratio for an indefinite period of time.
It does require, however, that reactors that are net producers of fissile material be
located in energy centers.
The maximum is less than 300 GWe through-
The utilization and movement of fissile material in year 2035 for Case 8L and the
small U308 supply are shown in Fig. 6.2-35. The LWR loaded with approximately 3% enriched
235U comprises approximately 13% o f the installed capacity, the denatured 235U LWR comprises
approximately 12%, the energy center FBR comprises approximately 29%, the denatured 233U LWR
comprises 8%, and the denatured FBR comprises 38%. The denatured 235U LWR is being rapidly
phases out of the nuclear system in year 2035, while the denatured 233U LWR is being
rapidly phased in. This is indicated in Fig. 6.2-35 by the fact that the heavy metal dis-
charge for the denatured 235U LWR is considerably greater than the heavy metal charge,
while the heavy metal charge for the denatured 233U LWR is considerably greater than the
heavy metal discharge. The former is indicative of final core discharges, while the latter
is indicative of first core loadings.
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