Complexing & chelating agents TB01

This report was prepared for the Belgian Agency for Radioactive Waste and Enriched Fissile Materials ONDRAF/NIRAS (O/N) being in charge of the short- and long-term management of all types of radioactive waste and keeping the quantitative and qualitative radionuclide inventory up to date. The waste treatment and conditioning, i.e. its transformation into a stable end product, ready for intermediate storage and/or final disposal is managed by Belgoprocess, a subsidiary of O/N. The waste is classified in several categories and for each of them specific treatment and conditioning processes are applied. In 2006, the Federal Government decided that low- and intermediate level waste or category A waste can be disposed in a surface disposal facility in the municipality of Dessel (province of Antwerp). Industrial processes and maintenance activities generate different waste streams, which may be solid, liquid or in gaseous form. The waste considered in this report is the so-called CONCT-CNT-400 waste family resulting from the processing and conditioning of effluents on the site of the Tihange Nuclear Power Plant (CNT - Centrale Nucléaire de Tihange). The waste treatment comprises homogenization, flocculation/precipitation, evaporation and finally immobilization/conditioning of the remaining concentrate in cement. Although the mentioned waste family has been already radiologically characterized and chemically analyzed, uncertainty exists on the presence and quantity of organics originating from decontamination activities of the CNT. Therefore, O/N asked to compile a report elucidating the main properties of EDTA, oxalate and picolinate being expected to be the major organic components in the concentrates and to evaluate their influence on the retention and solubility of the waste relevant radionuclides. The report is subdivided into two major parts with the 1st part being dedicated to the description of the waste family CONCT-CNT-400, its characteristics, the conditioning procedure and the waste packages prepared for final disposal. In the 2nd part, the properties of the three organics are described in detail, followed by a literature review about their influence on radionuclide speciation/complexation, solubility and sorption under cementitious conditions.