The entire cross section of a Cobalt 59 atom is only about a barn. Since a nuclear weapons dispersion of neutrons is in three dimensions and therefore the conce

The entire cross section of a Cobalt 59 atom is only about a barn. Since a nuclear weapons dispersion of neutrons is in three dimensions and therefore the concentration of neutrons drops quite quickly as a measure of distance the car will have to be uncomfortably close to transmute a meaningful amount of Cobalt 60. Since this phenomena is very much geographically constrained by the properties and physics of the blast, using over the top comparison of "15 pounds could kill 24 million people" should instead read "15 pounds generated from 240,000 micronuclear explosions generating this material near 100 people each could kill 24 million people if they decide to linger near the Cobalt 60 on the order of years due to its long half life". Edit: It is important to understand the underlying physics to make an accurate characterization of the risks involved. Cobalt 60 is not the most deadly substance to humans; I would argue alcohol is higher than Cobalt 60.