Options for Determining Equivalent MHTM (Metric Tons of Heavy Metal) for DOE High Level Waste

Section 114(d) of the Nuclear Waste Policy Act of 1982, as amended (NWPA), limits the overall capacity of the first repository to 70,000 metric tons of heavy metal (MTHM). Current DOE policy is to allocate DOE spent fuel and high-level waste (HLW) at 10 percent of the total, or 7,000 MTHM. For planning purposes, 4,667 MTHM will be allocated for HLW. While the NWPA provides a technical basis for determining the MTHM equivalence of HLW, it does not address the significant technical differences between DOE HLW and commercial spent nuclear fuel (SNF). Although more than 170,000 MTHM of DOE fuel has been reprocessed to produce the inventory of HLW, the amount of radioactive waste generated per metric ton of DOE fuel is only a few percent of that in a metric ton of commercial fuel. This study compares the results of four methods for determining the MTHM equivalence of DOE HLW. These methods include (1) using the actual weight of heavy metal in reprocessed DOE fuel, (2) assuming the historical equivalence of 0.5 MTHM/canister of vitrified DOE HLW, (3) comparing the total radioactivity in DOE HLW to the radioactivity of commercial SNF, and (4) comparing the total radiotoxicity of DOE HLW, as defined for those radionuclides identified in 10 CFR 20, with SNF at 1,000 and 10,000 years. This study concludes that either of the last two options would meet Congress's stated purposes of the NWPA, which are to (1) provide ''reasonable assurance that the public and the environment will be adequately protected from the hazards posed by high-level radioactive waste and such spent nuclear fuel as may be disposed of in a repository'', and (2) to ''define Federal policy for the disposal of such waste and spent fuel''.