what is the half life of the expended fuel?
I thought I heard somewhere that the half life of the most long-lived radioactive isotopes from thorium decay will reach background levels in 300 years, so that means 10 half lives if my memory serves me right.
That would give the longest lived waste isotope a 30 year half life...I think. Sigh, I don’t remember much of that stuff anymore.
The Thoriun fuel cycle produces fewer actinides, which have long half lives.
More importantly, with a lftr, the fuel is liquid, so it “burns” more than 90% of the fissionable material. With a light water reactor, the fuel is solid, contained in ceramic pellets. Only about 4% of the fissionable “rock” is burned.