Advantages of separation of high-level nuclear waste into two waste categories

High-level nuclear waste (HLW) contains two groups of radioactive nuclides with very different characteristics: 1. the 'heat generators' which produce heat during a few hundred years and 2. the long-living radioactive nuclides, especially the 'transuranes', which remain radioactive for a very long time with practically no heat production. The presence of each group leads to special demands for waste disposal. Separation of the HLW into two waste categories, a heat generators category and a transuranes category, may lead to a simpler, safer and more efficient disposal of the waste. A first analysis of separation of HLW into two waste categories is presented. This analysis is based on relative toxic risks: both radiotoxicity and chemical toxicity are taken into account. Four separation schemes have been considered. In connection with chemical separation aspects a favourable separation scheme proved to be the scheme where the transuranes category contains the actinides and the (non-radioactive) lanthanides and the heat generators category the rest of the HLW. (author). 16 refs.; 6 figs.; 8 tabs