The need to develop Thorium based Nuclear Energy as the major electric energy supply. 5. Radioactive waste from an LFTR decays down to background radiation in 300 years compared to a million years for U-235 based reactors.

 Radioactive waste from an LFTR (Liquid Fluoride Thorium Reactor)  decays down to background radiation in 300 years instead of a million years for U-235 based reactors. Initially LFTRs produce as much radioactivity as an U-235 based nuclear reactor, since fission converts mass to heat, but the decay products have a much shorter half-life. See the figure below.