Radiochemical analysis of chlorine-36

Abstract

The radioactive chlorine isotope, 36 Cl, decays with a half-life of 3×10 5 years by emitting a beta particle (98 %) and by electron capture. The aim of this paper is to propose a radiochemical separation method of 36 Cl 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 36 Cl inventory calculations. The separation method proposed is based on an oxidation technique where chlorine is trapped by NaOH. 36 Cl beta emissions are measured by liquid scintillation counting by the dual label technique in order to avoid the contamination produced by 14 C 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.

Chlorine cycling and the fate of Cl in terrestrial environments

“…In addition, seven radioactive isotopes exist of which six have half-lives of less than 1 h and are of less interest with respect to Cl cycling in the environment. In contrast, 36 Cl has a half-life of 3.01 10 5 years and decays with a maximum energy of 709.6 keV either by emitting a beta particle (98.1%) or by electron capture (1.9%) resulting in the end products argon-36 ( 36 Ar) and sulphur-36 ( 36 S), respectively (Peterson et al 2007 ; Rodriguez et al 2006 ).…”

Investigating the 36Cl memory effect in pyrolysis of solid samples from nuclear decommissioning activities

“…36 Cl, 129 I, 79 Se) present in materials coming from decommissioning activities are still under investigation [4][5][6][7][8][9]. 36 Cl is considered a critical radionuclide in terms of the safe storage of radioactive wastes because of its high mobility and long half-life (T 1/2 = 3.02E + 05 y) [6,10,11]. Construction materials used in the nuclear industry, such as steel, graphite, or concrete, may contain trace amounts of chloride that may undergo neutron activation when exposed to neutron fluxes.…”