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

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7.24<br />

the potentially greater delay in repository availability. Requirements for truck shipments<br />

are much larger than in the once-through cycle because <strong>of</strong> the assumption that all TRU waste<br />

drums and boxes are shipped by truck. These wastes could be shipped by rail; in that case,<br />

only 1/2 to 1/3 as many shipments would be required. More details <strong>of</strong> the transportation<br />

requirements with the reprocessing cycle are shown in Appendix A, Table A.7.2.<br />

7.3.4 Age <strong>of</strong> the <strong>Waste</strong> at Disposal<br />

A potentially beneficial aspect <strong>of</strong> delayed repository availability under the alterna-<br />

tive program is the aging <strong>of</strong> the waste, which reduces radioactivity and heat generation<br />

rates. The maximum and minimum ages at disposal for spent fuel from the once-through cycle<br />

and high-level waste from the reprocessing cycle are shown in Tables 7.3.7 and 7.3.8,<br />

respectively. To illustrate this aspect more fully, the ages <strong>of</strong> spent fuel and high-level<br />

waste for Case 3 are plotted as a function <strong>of</strong> time in Figures 7.3.10 and 7.3.11 for the<br />

once-through and the reprocessing cycles.<br />

The lower thermal output for the aged waste would permit either more waste to be placed<br />

in individual canisters and a higher areal loading <strong>of</strong> the repositories, or could be used to<br />

provide a greater level <strong>of</strong> technical conservatism by allowing reduced temperatures for<br />

emplaced wastes. For this analysis, the quantity <strong>of</strong> high-level waste placed in individual<br />

canisters has been adjusted to take advantage <strong>of</strong> the lower thermal output <strong>of</strong> the aged waste,<br />

and the calculated repository requirements take into account the lower thermal output <strong>of</strong> the<br />

aged waste. The relationship between age <strong>of</strong> the waste and repository capacity is discussed<br />

in Section 5.3.3 and Appendix K.<br />

TABLE 7.3.7. Maximum (and Minimum) Age <strong>of</strong> Spent Fuel Entering the<br />

Repository Using the Once-Through Cycle, Years<br />

Proposed Program Alternative Program<br />

Nuclear Power Growth (Geologic Disposal (Disposal Starting<br />

Case Assumption Starting 1990 - 2010) 2010 - 2030)<br />

1 Present Inventory<br />

Only 18(14) to 38(34) 38(34) to 58(54)<br />

2 Present Capacity<br />

and Normal Life 18(5) to 38(18) 38(18) to 58(38)<br />

3 250 GWe System<br />

by Year 2000<br />

and Normal Life 18(5) to 38(5) 38(5) to 58(19)<br />

4 250 GWe System<br />

by Year 2000<br />

and Steady State 28(5) 48(12)<br />

5 500 GWe System<br />

by Year 2040 28(5) 48(20)

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