Consequence ranking of radionuclides in Hanford tank waste [report]

F.A. Schmittroth, T.H. De Lorenzo
1995 unpublished
Table 2. Comparison of RHO (1985) values to ORIGEN2. The RHO (1985) report is the supporting document for the Hanford Defense Waste Environmental Impact Statement (HDW-EIS). 1971 to effect a more direct comparison. All values are given in curies decayed to the end of 1990. Sn 59.0 Th 59.0 Pb 59.0 EXPECTATIONS FROH THE PRETREATMENT The tank wastes will undergo pretreatment to separate the wastes into low-level and high-level components prior to vitrification. This includes a sludge wash and
more » ... ludge wash and other processing steps. reductions in the low-level waste stream are taken from (Boldt 1994) and are also included in Table 3. cesium, strontium, uranium, .plutonium, and americium. Large reductions are also expected for neptunium and iodine but not currently technetium. Current estimates for these The largest reduction factors are for carbon, EXPECTATIONS FROH CONTAMINANT IN THE SOIL The transport of emplaced waste t o a potential drinking water site is a significant contributor to estimated health consequences. The drinking water dose was thus selected as one basis for ranking the important radionuclides. Although there are multiple mechanisms that may impede contaminant transport, chemical retardation in the soil can be very significant and is used here to represent a waste reduction factor in going from the emplaced waste to the concentration in drinking water. WHC-SD-WM-RPT-163 Rev. 0 previous attention include the uranium daughter products, '3'Pa and 2'7Ac. Although their immediate parent ='Th (see Figure 2) is retarded, it is not an effective bar ier because of its short 26 half-life. The expected retardation of "'Pa and F27Ac needs to be confirmed. Although it is not dominant here, the current ORIGEN2 model did not include a significant amount of 233U generation from thoria irradiations. Becau2g;hey are more difficult to calculate, two other uranium isotopes, 84U and also merit further investigation. uncertain, and the current consistent with estimates from previous studies that have examined this problem in more detail. likely because of the 99% reduction credited in pretreatment. Another nuclide in the list that merits additional study is 233U. , The ranking of 14C is qltificially low. The calculation of 14C is C value should be adjusted upward to be more However, it still would not be highly ranked, most . 2 RETARDATION AND LONG-TERN RADIOACTIVE DECAY
doi:10.2172/409893 fatcat:snwqkke3jzcdzbrhzh6iqxfury