Marduk

If the radiation was from a bomb instead of a reactor or some natural radioactive deposit wouldn't it contain some tell tale sign like Strontium 90 or something of that sort that only bombs produce?

Thomas Cassidy

Bombs produce telltale signatures due to the manufacturing process used in the breeder reactor. When the fissile material is plutonium, for example, P239 is bred in a breeder reactor (sodium moderated) from common, non-fissile Uranium 238. During that breeding process the daughter products in the core tend to produce radicals in the plutonium giving a signature that can be traced to the plant of origin. The same is true if fissile uranium 233 is bred from thorium 232.

However, when the fissile material is not man-made, the signature contaminants will be lacking, so it would be hard to say what the origin of the material was. However, you are correct, a nuclear explosion will produce certain daughter products (most often barium and krypton) which are quite easily identified. The argument is, of course, that the daughter products which are produced by a nuclear explosion not only occur naturally, but also tend to dissipate (especially krypton, which is a gas) over time! Which is convenient for the theorists.

beausoleil

I would have expect some nuclides to be diagnostic of a recent radioactive contamination because they would be absent after 8000 years. 137Cs has a half life of about 30 years, for instance, and is produced from fission at about the 6% level. So there would be none left after 8000 years. Ought to stick out like a saw thumb, maybe by gamma spec? Ditto Sr90 as above.

<a href="http://sutekh.nd.rl.ac.uk/cgi-bin/CoNquery?nuc=Cs137" target="_blank">http://sutekh.nd.rl.ac.uk/cgi-bin/CoNquery?nuc=Cs137</a>