Plutonium measurements in Hanford DOE site waste samples

This paper describes development work to prepare a method to measure absolu te Pu-239 content and Pu-isotopics by ICP-MS in acidified Hanford DOE-site samples which are very high in Sr-90, Tc-99, and Cs-137 radioactivity and w hich are frequently high in organic carbon content. Samples with very large Sr-90 and Cs-137 contents have historically been difficult to analyze for Pu content by each of three alpha-counting techniques in use at SRS, and an alysis by ICP-MS in these samples is complicated by the high organics conte nt. We report an ion exchange chemical preparation to obtain fraction of Pu that does not contain any fission product contribution and no interfering organics to allow measure of absolute Pu-239 and of Pu-239 through Pu-241 i sotopics by ICP-MS. The method uses a Pu-242 spike to measure Pu recovery a nd is demonstrated in this paper with three distinct commercially available resins and with over 300 samples. Measured absolute Pu-239 contents in six ty-three spiked/unspiked duplicates have agreed within 15% precision. Overa ll Pu-242 recoveries were near 90% with 25% precision. Comparisons of absol ute Pu-239 contents measured directly on three samples agreed within the qu oted 25% uncertainty.