I began my professional career at a nuclear research facility , and part of the employment process was to be trained in the dangers of radioactive materials . We were shown a movie of a fellow who had worked in a hospital as a janitor . The hospital had a radioactive cobalt therapy unit for cancer treatments and he learned that the little cobalt pellet was worth a lot of money , so he found a way to steal it .
He put it in his pants pocket for the rest of his shift , then for some reason changed clothes or just put it in the other pocket . The pellet was not missed until the following day . It was easy to find the pellet with a geiger counter by just driving around the city . By the time they found it at his home , and now knowing his identity they arrested him at work . By that time he had a burn on each leg , which was then videoed , as was the daily progression of the damage to his body . Within a few days his scrotum was black and about the size of a small pumpkin … so he was castrated . By that time his thighs were becoming oozing , rotting flesh . A double amputation followed . He died within the following thirty days as I recall .
So , as others have posted , radioactive materials would not be good as currency . Besides they have decay half-lives … but so does our fiat fed money , come to think of it . The half life of money appears to be roughly twenty years .