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Measurement of plutonium isotopes in vivo is not feasible for radiation protection purposes. Considering the slow rate of plutonium excretion, the respect to annual dose limits, whenever risk of plutonium internal contamination occurs, implies the need of a monitoring programme based on very sensitive bioassay, i.e., measurement of plutonium content in samples of urine or feces, characterized by a very low minimum detectable activity. Alpha spectrometry is the most common measurement method applied in this field. The applicability of this method strictly depends on the procedure adopted for the sample radiochemical preparation preceding the real spectrometric counting and, particularly, on the element chemical recovery that is one of the parameters that mostly influence the minimum detectable activity achievable by the analysis. The aim of the present work is to compare the performances of four of the most widely adopted radiochemical procedures making use of different separation methods for the determination of plutonium in urine samples via alpha spectrometry. [ABSTRACT FROM AUTHOR]

The radioactive chlorine isotope, 36Cl, decays with a half-life of 3×105 years by emitting a beta particle (98 %) and by electron capture. The aim of this paper is to propose a radiochemical separation method of 36Cl from the other beta-gamma emitters present in low and medium radioactive wastes such as spent ion exchange resins and evaporator concentrates, that arise from Nuclear Power Plants and particularly in the wastes that come from decommissioning activities of graphite reactors, in order to provide data for 36Cl inventory calculations. The separation method proposed is based on an oxidation technique where chlorine is trapped by NaOH. 36Cl beta emissions are measured by liquid scintillation counting by the dual label technique in order to avoid the contamination produced by 14C which is also trapped by NaOH and which is the main contaminant present in graphite samples. The sensitivity of this method is sufficient to achieve the needed thresholds for the radiological characterization of the radioactive materials to which this method can be applied. [ABSTRACT FROM AUTHOR]