Electrochemical detector based on a modified graphite electrode with phthalocyanine for the elemental analysis of actinides.

The quantification of actinides in aqueous solutions involves complex and expensive separation processes. Electrochemical methods have been widely used for the quick and accurate identification and quantification of organic and inorganic compounds directly or indirectly. Therefore, this work proposes the use of modified graphite with phthalocyanine for electrochemical detection and quantification of Th, U, Pu, Am, and Cm, in aqueous media by cyclic voltammetry. The electrodes were characterized by Raman and infrared spectroscopy, and the cyclic voltammetry data were modeled with Aoki's model. The detection limits (DL) and the quantification limits (QL) reached by the electrochemical detection of these actinides were of the order of ppt. Aoki's model fitted perfectly with the experimental data. The functionalization of graphite electrodes promotes the formation of phthalic anhydride, and the phthalocyanine is anchored on the epoxy groups of the graphite. The electrochemical detection process of these actinides is indirect. This electrochemical detector is cheap and disposable and can be an alternative for an initial characterization of actinides in liquid waste.

Thin source spraying method for gross alpha/beta measurements with emphasis on alpha/beta particle self-absorption.

Gross alpha/beta analysis is an initial rapid screening technique used to discriminate alpha- and beta-particle emitters in the nuclear industry. Self-absorption in the sample affects the detection; therefore, self-absorption curves must be constructed. Beta and alpha self-absorption curves were constructed under different conditions. Results reproducibility depends on uniformity of the dry residue on planchets. To determine and compare activities correctly, the preparation method of the sample must be identical to the ones measured the construction of the self-absorption curves.

Decontamination of radioactive metal surfaces by electrocoagulation.

The decontamination of noncompactable radioactive wastes, such as tools and equipment, aims to reduce the waste volume to be conditioned and stored. The electrocoagulation (EC) application in the decontamination of noncompactable radioactive waste from stainless steel containing uranium, was studied to evaluate its technical viability. The first studies were carried out with stainless steel plates coated with WO3 to simulate a fixed contamination and to determine the best tungsten removal conditions via EC considering pH, electrolyte support, distance between the electrodes, cell potential and counter-electrode material. The best removal conditions for WO3 were applied to plates contaminated with UO2(NO3)2 to evaluate the viability of the EC decontamination process. Uranium removal efficiencies of 90% were obtained in 1 h, at pH of 1, 2.4 V and 1 cm of distance between anode / cathode in a circular array. The EC process, under the previously obtained conditions, was applied to two metallic pieces contaminated with U. It proved feasible to decontaminate metallic pieces through the EC process, thus being able to obtain up to 90% U removal efficiency; however, it is important that the surfaces of the parts are free of grease and dust.