Our group recently performed Pu isotope ratio measurements on archives of alpha spectrometry planchettes by means of Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). In close collaboration with the Norwegian Centre for Environmental Radioactivity (CERAD) institute, additional information (in this case the 240Pu/239Pu ratio) was extracted from existing samples, of which only the total 239+240Pu activity is known. By knowing the specific 240Pu/239Pu signature one can discriminate weapons-grade Pu from civil reprocessing sources, allowing for instance monitoring of the environmental transport of weapons-grade Pu released from production sites, e.g. from Mayak PA, in the Ural region, towards the Arctic Ocean. This is, to our knowledge, the first report on the use of LA-ICP-MS for the measurement of weapons-grade Pu isotope ratios associated with nuclear legacy samples from the former Soviet Union. Moreover, we have verified the feasibility of Pu isotope ratio determination by means of a quadrupole mass analyzer.
(a) 239Pu, 240Pu and 240Pu/239Pu distribution maps in sediment
from Mayak's Reservoir 10 and (b) the histogram of 240Pu/239Pu ratio