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6.0. INTRODUCTION
In this chapter civilian nuclear power systems that utilize denatured 233U fuel to
various degrees are analyzed to determine whether they could meet projected nuclear power
demands with the ore resources assumed to be available. The reactors employed in the systems
are those discussed in earlier chapters of this report as being the reactors most likely to
be developed sufficiently for commercial deployment withi-n the planning horizon, which is
assumed to extend to the year 2050. The reactors included are Light Water Reactors (LWRs),
Spectral-Shift-Controlled Reactors (SSCRs) , Heavy Water Reactors (HWRs) , HighlTemperature
Gas-Cooled Reactors (HTGRs), and Fast Breeder Reactors (FBRs). In each case, the nuclear
power system is initiated Gith currently used LWRs operating on the low-enriched 235U fuel
cycle, and other converter reactors and/or fuel cycles are added as they become available.
On the basis of information provided by the reactor designers, it is assumed that 235U-fueled
LWRs alone will be utilized through the 1980s and that LWRs operating on denatured 233U and
239Pu w ill become available in the early 1990s. It i s also assumed that SSCRs operating on
the various fuel cycles will become available in the early 1990s. Thus nuclear power systems
consisting of LWRs alone or of LWRs and SSCRs in combination, with several fuel cycle options
being available, could be introduced in the early 1990s.
LWR-HWR and LWR-HTGR systems could be
expected in the mid 199Os, and FBRs could be added to any of the systems after the year 2000.
The nuclear power systems utilizing denatured 233U fuel were +vided into two major
categories: those consisting of thermal converter reactors only ar.d those consisting of
both thermal converters and fast breeders. Three "nuclear policy options" were examined
under each category, the individual options dfffering primarily in the extent to which
plutonium is produced and used to breed additional fissile material. For comparison, a
throwawaylstowaway option employing LEU converters was also analyzed, and two options
utilizing the classical plutonium-uranium cycle were studied, one using converters only
and the other using both converters and breeders.
All of the options studied were based on the concept of secure energy centers and
dispersed reactors discussed in previous chapters. Thus, all enrichment, reprocessing, and
fuel fabrication/refabrication activities, as well as fuel and/or waste storage, were assumed
to be confined to the energy centers. In addition, all reactors operating on plutonium or
highly enriched uranium were assigned to the centers, while reactors operating on low-enriched
or denatured uranium were permitted to be outside the centers. Determining the precise nature
and structure of the energy center was not within the scope of this study. Presumably it
could be a relatively small localized area or a large geographical region covering an entire
nuclear state, or even a collection of nuclear states. If more than one country were involved,
the sensitive facilities could be nationally owned but operated under international safeguards.
But whatever the character of the center an important consideration for any nuclear policy option
is its "energy support ratio," which is defined as the ratio of the nuclear capacity
installed outside the center to the capacity installed inside the center. Only as the support
ratio increases above unity is the capability of the system to deliver power to dis-