Development of in situ fission track analysis for detecting fissile nuclides in contaminated solid particles

A fission track analysis (FTA) technique was developed to identify hot particles in a contaminated soil or sediment. To identify the location of fissile particles in a contaminated sample, SEM grids electroplated with U or Th were used to record reference points on the Lexan track detector. The track image of the grid coated with Th, as a result of the Th232 (fast neutron, f) reaction, was recorded clearly on the Lexan track detector whereas the track images of the grid coated with U were too dense to be used for FTA. The grid coated with thorium can provide more useful information on locating fissionable nuclides such as uranium and plutonium isotopes in contaminated sample material. FTA with grids electroplated with Th was applied to contaminated soil so that hot particles in the soil were identified within the finder grid and could be separated from the sample matrix for studying speciation of hot particles.