Quantification of 239Pu radioactivity in swipe samples by accelerator mass spectrometry

In the AMS Laboratory at the Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH) in Bucharest, Romania plutonium measurements started a few years ago. In the course of this period, we chemically processed environmental samples that could have contaminated the laboratory with 239Pu in the femtogram range. Swipe samples taken in the sample processing laboratory were investigated to quantify the potential plutonium contamination. Following the accelerator mass spectrometry measurements, the limit of detection for 239Pu in the order of 1 fg was determined, while the amount of 239Pu in the swipe samples was around 2 fg. The chemical procedure and the AMS measurement were validated by analyzing simulated swipe samples as a part of a proficiency test organized by the International Atomic Energy Agency. The obtained results show that the 1MV AMS system at IFIN-HH can be routinely used for determination of 239Pu concentrations in environmental matrices.