Simultaneous determination of Np, Pu and Am in HNO3 solution by combining extraction, liquid scintillation counting, and α spectrometry

α Spectrometry is one of the most important and sensitive techniques for the assay of α-emitting nuclides, but various complicated procedures are often required for preparation of uniform thin plate source. Liquid scintillation counting (LSC) with pulse shape analysis (PSA) combining extraction is much simpler, more rapid and accurate technique, but the extraction processes are often very long. By combining extraction, LSC with PSA, and α spectrometry, we proposed a new approach to determine ²³⁷Np, ^238–240Pu and ²⁴¹Am. The new approach includes an extraction process of three steps for blind samples or of only one step for those samples without tailing interference with α spectra. Moreover, no complicated procedure is required for α plate source preparation because even non-uniform plate source is feasible for the new approach. The approach has taken advantages of high counting efficiency (nearly 100%) of LSC for α-radiation, high energy resolution of α spectrometry and high recovery yield of actinides by trialkylphosphine oxide (TRPO) extraction. The approach with one step extraction can be expected to determine ²³⁷Np, ^238–240Pu, ²⁴¹Am and ²⁴⁴Cm simultaneously.