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The potential nuclear contribution with LWRs on the throwaway cycle, both with and
without a fuel system designed for extended exposure' being included, is shown in Fig. 6.2-2
for the high-cost U308 supply. The nuclear contribution passes through a maximum of
approximately 420 GWe installed capacity in about 2010 and declines continuously thereafter,
the system with the LWR-EE providing a slightly greater capacity over most of the period.* The
cumulative capacity constructed throughout the planning horizon is approximately 600 GWe. The
maximum installed capacity is less than the cumulative capacity because new units must be con-
structed to replace those retired during the period.
72,000 ST/yr and the maximum annual enrichment requirement is 45 million SWU/yr, neither of
which can be regarded as excessive.
the size of the economic U308 supply.
The maximum annual U308 requirement is
Thus, the principal limitation, in this case, is simply
A more costly U308 supply would, of course, imply a smaller maximum installed
capacity occurring earlier in time, while the converse would be true for a cheaper
U308 supply. As is shown in Fig. 6.2.3, if the U308 supply were a factor of two larger, the
maximum nuclear contribution would increase from approximately 420 GWe to approximately
730 GWe and would occur at about the year 2030. If, on the other hand, the supply were a
factor of two smaller, the maximum nuclear contribution would decrease to approximately
250 GWe and would occur in about the year 2000. A cross-plot of the effect of the U308 Supply
on the maximum installed nuclear capacity for the LWR on the throwaway cycle is shown in
Fig. 6.2-4. It i s noted in Fig. 6.2-3 that if the U308 supply should be as large as 6.0
million ST, the maximum annual U308 Pequirement would be 120,000 ST/yr and the maximum
annual enrichment requirement would be 77 million SWUlyr.
the amount of U308 that could be mined and milled annually, these annual U308 requirements
could be the limiting factor.
Given the probable limitation on
The effect of adding an advanced converter (SSCR, HTGR, or HWR) to a nuclear power
system operating on the throwaway cycle with the high-cost U308 supply is shown in
Fig. 6.2-5. The increase in the nuclear contribution for each of the advanced converter
options is relatively small. At most the maximum installed nuclear capacity increases by
approximately 30 GWe and the year in which the maximum occurs by approximately three
years. Adding the SSCR to an LWR produces a slightly greater nuclear contribution than
adding an HTGR. This may at first appear to be a paradox since the lifetime U308 require-
ment for the HTGR is less than that for the SSCR (see Fig. 6-2.1), but the 4-yr difference
in introduction dates is sufficient to offset the difference in U308 requirements. (The dif-
ference is not large enough to be significant, however.) The reason that so small an increase
in nuclear capacity is realized by introducing the'various converters is that by the time
they dominate the nuclear system a very significant fraction of the U308 supply has already
been committed to the standard LWR. This is illustrated in Fig. 6.2-6, where an HWR intro-
duced in 1995 does not become dominant until 2010. It follows that if the U308 supply were
larger with the same nuclear growth rate, or if the nuclear growth rate were smaller with the
same U308 supply, the addition of an advanced converter would have a greater impact. This
is illustrated in Fig. 6.2-7, for which the intermediate-cost U308 supply was assumed, and
-unless a system consisting of the standard LWR alone is designated, it is
the LWR system including an LWR-EE that is denoted as 1L and compared with other systems in
later sections of this chapter. However, as pointed out here, the installed capacities of
the two LWR systems differ only slightly.
,