Assay and identification of plutonium of different grades present in sub- Becquerel level by fission track technique

Alpha activity estimation in sub-Becquerel level is required for environment and forensic applications. In the present studies, an attempt has been made to use fission track technique in combination with the scintillation measurement, to get fission track to gross alpha activity ratio. The latter can be possibly treated as an indication of the grade of Pu in the sample if selective and quantitative extraction of Pu in presence of Am is achieved. In this work, the developed ion imprinted PET substrates were used for selectively quantifying total Pu in ~10-500 mBq activity range. These PET samples were loaded with Pu of both the research (RR) and power reactor (PR) grade and were quantified using alpha based scintillation counting. The fission tracks are a result of n-induced fission of ²³⁹Pu mainly, which is higher in a RR grade Pu sample, and hence higher track density for equivalent total Pu content. Also, as seen from the 10x images of both the grade Pu samples, uniform distribution of tracks is observed