Method for determining plutonium in air filters in detection of nuclear activities

A method was developed to determine activities and isotope ratios of plutonium and uranium. The method includes dry and wet ashing of air filters and separation of plutonium and uranium from each other and from other nuclides on Eichrom®'s extraction chromatography resins UTEVA and TRU. Interferences in plutonium separation caused by thorium and polonium were investigated and eliminated. A field trial was performed in Kurchatov, Kazakhstan, to test the aerosol sampling and radiochemical methods developed for plutonium and uranium. In the air samples collected, the activity of 2 3 9 , 2 4 0 Pu varied between 0.67 and 228 Bq/kg of dust, the activity of 2 3 8 Pu from 0.20 Bq/kg to 16.4 Bq/kg of dust, and the isotopic ratio 2 3 8 Pu/ 2 3 9 , 2 4 0 Pu between 0.011 and 2.4. Concentrations of Pu isotopes in the air were 13.4-2490 nBq/m 3 for 2 3 9 , 2 4 0 Pu and 7.2-960 nBq/m 3 for 2 3 8 Pu. Radioactivity of 2 3 9 , 2 4 0 Pu in air filters from Astana varied between 0.075 and 0.72 Bq per kg of dust and that of 2 3 8 Pu between 0.038 and 0.14 Bq/kg of dust. Activity concentration of 2 3 9 , 2 4 0 Pu in the air of Astana was 5.0-130 nBq/m 3 .