Evolution of an exothermic waste package with caesium and strontium
We have taken the fission products with a high thermal output (caesium and strontium) out of the standard package so that they can be conditioned separately in a second package. The exothermic package containing the strontium and caesium does not have to be put into a deep geological disposal facility at the start. It just needs to be left to wait for a long while. Because of radioactive decay, after 300 years, it would only be giving off one watt, since its radioactivity would have decreased by a factor of a thousand.