Radiochemical analysis of chlorine-36

Abstract

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.