Development of a determination method of ²³⁷Np in the Environment with mass spectrometry.

Abstract

The importance of environmental ²³⁷Np has been suggested as a tool for environmental dynamic research, in addition to search for radiation effects, due to physicochemical properties of Np. However, the ultra-trace level of the nuclide is difficult to measure accurately with a mass spectrometer and has not been comprehensively studied because of the lack of a spike for the chemical separation of Np in environmental samples and their measurements. In this study, we attempted to newly produce ^236gNp as an Np spike and establish a chemical separation method for purification of the spike. A purification method of Np with a good recovery rate was established using TEVA, TK400 and UTEVA resins, and was applied to the sample which was irradiated to produce the Np spike. We successfully detect and quantify the by-product ^236mNp in the irradiated samples. From these results, the amount of ^236gNp produced by irradiation could be evaluated. Further, a basic study on the Np collection from seawater using amidoxime-type adsorbent was carried out to apply the Np spiking method to hydrosphere samples.