The Nuclear Waste
It should be realized that the amount of waste produced by a nuclear heat source is much and much smaller than the amount of waste resulting from fossil fueled engines, simply because the fission process liberates the energy that keeps a nucleus together (which is typically in the order of hundreds of millions of eV's), instead of a chemical reaction, that makes use of the binding energy of electrons (which is only several eV's). The presently proposed nuclear heat source uses its fuel very economically, thus resulting in even smaller amounts of waste (and in lower fuel costs!). The fuel elements themselves are ideal waste containers: after some three years of operation the core can be replaced by a fresh one and the old core serves as a waste container. The high burn-up of the fuel makes reprocessing unnecessary.
After three years of operation about 7 m3 of fuel pebbles are removed from the core. This nuclear waste can be transported in shielded containers. A possible design has a diameter of <3 m and a height of 5 m. After about 10 years the radioactivity and heat production have decayed to such an extent that the waste can be classified under the category “Medium-active waste of the upper category”. After 10 – 50 years of interim storage, the waste can be sent to final storage in relatively simple 0.4 m3 drums. It must be stressed that this is mainly due to the high mechanical and chemical integrity of the fuel elements, which simplifies their final confinement from the biosphere.