Management of Commercially Generated Radioactive Waste - U.S. ...

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fuel, 4) the long time for spent recycle fuel to work its way through the inventory to
reprocessing, and 5) the year 2040 cutoff date for this analysis. No third-recycle fuel is
irradiated in the Year 2010 reprocessing case. The same effect is noted in Case 4 and
Case 5. We calculate that at equilibrium, 4 MT of third-recycle plutonium would be dis-
charged for each 1,000 MT of equilibrium plus recycle reload fuel charged (equilibrium
reload fuel accounts for approximately 80% of the total fuel). Thus, for Case 3 for
example, where 239,000 MT of fuel are charged, the eventual implied commitment for third-
recycle plutonium disposal is approximately 780 MT.
7.3.8 Radioactivity Inventory in Disposal Repositories
The total radioactivity and the total heat output from the entire inventory of all
wastes sent to disposal from the entire system are summarized in Tables 7.3.13 through
7.3.16. These tables show the activity and heat output from year 2070 at periodic intervals
for the next 1 million years for each of the nuclear growth cases. By the year 2070, all
wastes have been placed in the repositories and much of the shorter life activities have
decayed to low levels. Detailed tables showing the breakdown of radioactivity and heat out-
put by individual nuclides are included in Appendix A.2 and A.3.
Table 7.3.13 shows the radioactivity inventory for all the fission and activation pro-
ducts. The radioactivity here is roughly proportional to the total energy produced in each
case (see Table 7.1.1). The fission and activation product inventory for the reprocessing
cases is closely similar to the fission and activation product inventory for the once-
through cases.
Table 7.3.14 summarizes the total radioactivity inventory for all of the actinides and
their daughter nuclides. The activity inventories in the once-through cases are roughly
proportional to the energy generated in each case. This is also true for the reprocessing
cases. However, the actinide inventories for comparable reprocessing and once-through cases
are substantially different. The actinide activity initially is much higher with the once-
through cycle wastes. This is because these wastes contain all of the plutonium present in
the spent fuel. However, the recycle wastes contain a much higher level of the higher
actinides--americum, curium, etc. Thus, the difference in total actinide activity inven-
tories is not as large as one might expect based just on the plutonium content, and the dif-
ferences become smaller in later years. Reprocessing Case 3 shows that the reprocessing
date significantly effects the total actinide activity inventory in the wastes.
Table 7.3.15 shows total heat output for the fission and activation products and
Table 7.3.16 shows heat output for the actinides and their daughter nuclides. These tables
show that in all cases, the heat output is dominated by the actinides after the first
500 years.
Comparisons of the toxicity of radioactive wastes on the basis of hazard indices is
discussed in Section 3.4. The relative toxicities of the once-through cycle and