The Application of radiochronometry during the 4th collaborative materials exercise of the nuclear forensics international technical working group (ITWG)

第4回核鑑識共同試料分析演習における年代測定法の適用

Kristo, M. J.*; Williams, R.*; Gaffney, A. M.*; Kayzar-Boggs, T. M.*; Schorzman, K. C.*; Lagerkvist, P.*; Vesterlund, A.*; Ramebck, H.*; Nelwamondo, A. N.*; Kotze, D.*; Song, K.*; Lim, S. H.*; Han, S.-H.*; Lee, C.-G.*; 大久保 綾子; Maloubier, D.*; Cardona, D.*; Samuleev, P.*; Dimayuga, I.*; Varga, Z.*; Wallenius, M.*; Mayer, K.*; Loi, E.*; Keegan, E.*; Harrison, J.*; Thiruvoth, S.*; Stanley, F. E.*; Spencer, K. J.*; Tandon, L.*

Kristo, M. J.*; Williams, R.*; Gaffney, A. M.*; Kayzar-Boggs, T. M.*; Schorzman, K. C.*; Lagerkvist, P.*; Vesterlund, A.*; Ramebck, H.*; Nelwamondo, A. N.*; Kotze, D.*; Song, K.*; Lim, S. H.*; Han, S.-H.*; Lee, C.-G.*; Okubo, Ayako; Maloubier, D.*; Cardona, D.*; Samuleev, P.*; Dimayuga, I.*; Varga, Z.*; Wallenius, M.*; Mayer, K.*; Loi, E.*; Keegan, E.*; Harrison, J.*; Thiruvoth, S.*; Stanley, F. E.*; Spencer, K. J.*; Tandon, L.*

最新の核鑑識国際共同試料分析演習では、低濃縮ウラン試料について、10か国の核鑑識ラボラトリーが精製年代測定を実施して良好な結果を得た。これらの測定のうち、3つの異なる核種ペアを用いた精製年代測定も実施された。10か国の核鑑識ラボラトリーが提出した精製年代測定の結果は、実際の精製日と概ね一致した。また、質量分析法による結果は、放射線計測法を用いたものに比べて、高精度な結果を示した。さらに、一部のラボラトリーによって示されたU-Pa法とU-Th法による精製年代測定の結果の一致は、結果の確証性を高めた。

In a recent international exercise, 10 international nuclear forensics laboratories successfully performed radiochronometry on three low enriched uranium oxide samples, providing 12 analytical results using three different parent-daughter pairs serving as independent chronometers. The vast majority of the results were consistent with one another and consistent with the known processing history of the materials. In general, for these particular samples, mass spectrometry gave more accurate and more precise analytical results than decay counting measurements. In addition, the concordance of the U-Pa and U-Th chronometers confirmed the validity of the age dating assumptions, increasing confidence in the resulting conclusions.