Decay calculations on medium-level and actinide-containing wastes from the LWR fuel cycle. Pt. 1

A number of basic data on medium-level and actinide-containing waste streams from the LWR fuel cycle were evaluated and the activity and thermal decay power were calculated for the nuclide inventories of cladding hulls and fuel assembly structural materials, for feed clarification sludge, medium-level aqueous process waste, low-level solid transuranium waste and for medium-level reactor operating waste. The activity as a function of decay time of the medium-level wastes decreases within 500 to 600 years by 1 to 3 orders of magnitude and is at the same time about 1 to 2 orders of magnitude lower than the activity of the high-level waste. The thermal decay power of the medium-level wastes decreases after 10 to 100 years by about 3 orders of magnitude and is about a factor of 10 to 100 less than that of high-level waste. In the very long term the residual activity (and thermal power) decreases only slowly due to the long halflives of the dominant actinides. The activity after more that 1000 years is about 1 to 2 orders of magnitude lower than that of high-level waste, the low-level transuranium waste by a factor 10 to 4, respectively. The activity per unit volume of the packaged waste of the medium-level and actinide-containing wastes because of the bigger volume of the conditioned wastes is lower by 2 to 4 orders of magnitude up to about 500 years. After more than 1000 years the activities per unit volume are lower by a factor of 20 to 200 than that of high-level waste. (orig.)