A Simple Radioactivity Determination Technique by Alpha-Ray Spectrometry for Homogenous Thick Sample

Alpha-ray spectrometry for a plane thick sample in which radioactivity is homogeneously distributed was applied to the determination of alpha-emitting radioisotopes without chemical separation processes. A homogenous glass sample containing alpha-emitting radioisotopes could be prepared by borax bead reaction. An alpha-ray spectrum of the glass sample containing 228Th indicated that release of 220Rn from the sample, which causes contamination of a detector surface with daughter nuclides of 220Rn, was almost negligible. Concentrations of alpha-emitting radioisotopes of Th series in the glass sample were determined quantitatively from the alpha-ray spectrum and stopping power of the medium calculated from its chemical composition. In the glass sample made from borax and spent fuel solution, radioactivity concentration of 244Cm, 238Pu+241Am, and total alpha were comparatively consistent with those obtained by the precision method of radiochemical analysis.