Rapid method for the determination of actinides in soil and sediment samples by alpha spectrometry

Abstract

A rapid procedure for the determination of Am, Pu, Th and U radionuclides in soil and sediment samples is described that can be used for environmental monitoring in emergency situations. The method is based on the fast and complete destruction of small amounts (up to 0.5 g) of samples by lithium metaborate fusion, followed by pre-concentration of the actinides by co-precipitation with calcium fluoride in acidic solution, and separation of the actinides by selective extraction chromatography using a single column filled with TRU resin. Am, Pu and Th are stripped separately, while U and Np are stripped together. Alpha sources are prepared from the chromatographic strip solutions directly by micro-co-precipitation with neodymium fluoride. Activities are determined by means of isotope dilution alpha spectrometry. The method provides accurate and reliable results for the activity concentrations of elevated levels of ^239,240Pu, ²³⁸Pu, ²⁴¹Am and natural levels of Th nuclides in soil and sediment samples in course of 24 h. By further purification U and Np nuclides can be separated and determined, too.