ORNL-5388 - the Molten Salt Energy Technologies Web Site

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The introduction of the classical Pu-U/U FBR in Option 3 results in an additional ore
and enrichment savings of about a factor of two from that in Option 2 except for the HTGRs.
Note, however, that in Option 2 the HTGRs already had a low ore and enrichment usage.
Option 3 all the advanced converter cases have about the same usage.
Recycling uranium i n denatured reactors and throwing the pluton um away (Option 4)
requires enrichment about halfway between Options 1 and 2. Compared w th the classical
recycle of plutonium in thermal reactors (Option 2), Option 4 consumes roughly the same
quantity of uranium with LWRs and SSCRs.
SSCRs is nearly balanced by throwing away the plutonium.
are considerably reduced over those of Option 2 when 233U is recycled compared to recycling plu-
tonium.
more favorable U308 utilization in Option 4 compared to Option 2. In contrast, the HTGRs in
Option 4 look much worse than in Option 2. This is because the HTGRs were already operating
on the 233UITh cycle in Option 2.
highly enriched fuel while in Option 4 they use denatured fuel.
That is, the increased worth of 233U in LWRs and
In
The requirements for HWRs, however,
The very low fissile requirements for the denatured 233U HWRs is responsible for the
However, in Option 2 the uranium-fueled reactors all use
Options 5U and 5T allow the recycle of plutonium in plutonium/thorium transmuters,
the difference between the two being that denatured 235U reactors are available in 5U whereas
they are not in 5T. This forces the 5T system to initially rely on the Pu/Th-fueled reactors
for 233U. Compared to Option 4, Option 5U results in 20 to 25% savings in ore usage and
Option 5T in 10 to 15% savings. The HWRs are the most efficient advanced converters for
uranium and enrichment utilization for Options 5U and 5T.
Option 6 introduces FBRs with thorium blankets, a1 though these FBRs have uranium as
fertile material in the core.
have approximately the same resource utilization. Option 7 is identical to Option 6 except
the denatured 233U FBR is included. The impact of this reactor on resource utilization for
these cases is small.
Comparing Option 6 with Option 3 reveals that both systems
In Option 8 the Pu-U-fueled FBRs of Option 7 are replaced with Pu-Th-fueled FBRs. The
longer doubling time of this reactor type results in somewhat increased uranium and enrichment
requirements. A key point for all of the systems containing FBRs (Options 3, 6, 7, and 8)
is that the ore and enrichment usage is relatively independent of the advanced converter
option. This is in contrast to the nonbreeder systems where the type of advanced converter
available (LWR, SSCR, HWR, or HTGR) much more strongly affects the resource utilization.
Another very important point that needs emphasis is that the superior ore utilization
of the HWRs relative to the other advanced converters for the alternate fueled systems
(Options 4 - 8) is directly dependent on the denatured 233U-fueled HWR. Of all the reactor
designs, the design of alternate fueled HWRs have probably received the least amount of analy-
sis and therefore have the largest uncertainty. Thus, before it can be concluded that the
HWRs offer significant resource savings, more work needs to be performed to verify the
optimistic performance characteristics of the denatured 233U-fueled HWR.