Plutonium and Uranium from Weapons Testing: Characterizing the Long-Lived Source Term in Fallout

摘要

This study demonstrated that it is possible to combinemapping of major element composition to plutoniummapping by autoradiography in order to gain a betterunderstanding of plutonium segregation in fallout, and therelationship between plutonium and the primary constituentsof fallout glasses. It was found that this sample set of falloutcould be described with a small number of endmember compositions. Furthermore, it was shown that plutoniumwas most strongly associated with the mafic glassendmember composition and excluded from the pureendmember compositions of felsic glass, SiO_2, andinclusionary phases. This may explain previousobservations of plutonium correlation with the elementscalcium and iron and the anti-correlation with potassiumand sodium in trinitite.4 In light of this study, it may beconcluded that this is a correlation with a mafic glassendmember, but that the relationship with Ca and Fe maynot apply when the Ca and Fe are from a different source.This study establishes a correlation with the mafic glasscomposition and an anti-correlation with felsic glass, SiO_2,and inclusion-like endmembers, and emphasizes that it islikely the characteristics of the endmember composition asopposed to the chemical characteristics of the individualelements that drive this behavior. Plutonium co-locationwith major element composition cannot be explained by thecondensation temperature of the components or thesolidification temperature of the composition. Viscositymay be a determining factor for plutonium incorporationinto nuclear fallout melt glasses.