Analysis of 236U and plutonium isotopes, 239,240PU, on the 1 MV AMS system at the Centro Nacional de Aceleradores, as a potential tool in oceanography

[摘要] The performance of the 1 MV AMS system at the CNA (Centro Nacional de Aceleradores, Seville, Spain) for U-236 and Pu-239,Pu-249 measurements has been extensively investigated. A very promising U-236/U-238 abundance sensitivity of about 3 x 10(-11) has been recently achieved, and background figures for (PU)-P-239 of about 10(6) atoms were reported in the past. These promising results lead to the use of conventional low energy AMS systems for the analysis of U-236 and Pu-239 and its further application in environmental studies. First U-236 results obtained on our AMS system for marine samples (sediments and water) are presented here. Results of two new IAEA reference materials (IAEA-410 and IAEA-412, marine sediments from Pacific Ocean) are reported. The obtained U-236/Pu-239 atom ratios, of 0.12 and 0.022, respectively, show a dependency with the contamination source (i.e. local fallout from the US tests performed at the Bikini Atoll and general fallout). The results obtained for a third IAEA reference material (IAEA-381, seawater from the Irish Sea), are also presented. In the following, the uranium and plutonium isotopic compositions obtained on a set of 5 intercomparison seawater samples from the Arctic Ocean provided by the ETH Zurich are discussed. By comparing them with the obtained results on the 600 kV AMS facility Tandy at the ETH Zurich, we demonstrate the solidity of the CNA technique for U-236/U-238 determinations at, at least, 7 x 10(-10) level. Finally, these results are discussed in their environmental context. (C) 2015 Elsevier B.V. All rights reserved.

[发布日期] 2015-10-15

[效力级别]  Proceedings Paper

[关键词] Plutonium isotopes;U236;Seawater;Sediments;Oceanography