Advanced Vitreous Wasteforms for Radioactive Salt Cake Waste Immobilisation
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MRS Advances © 2020 Materials Research Society DOI: 10.1557/adv.2020.45
Advanced Vitreous Wasteforms for Radioactive Salt Cake Waste Immobilisation Vladimir A. Kashcheev1, Nikolay D. Musatov1, Michael I. Ojovan2 1
A.A. Bochvar High-technology Research Institute of Inorganic Materials (VNIINM), Moscow, Russia M.V. Lomonosov Moscow State University, Radiochemistry Department, Moscow, Russia
2
Abstract: Salt cake radioactive waste is a remnant solid salt concentrate after deep evaporation of radioactive evaporator concentrate at WWER NPP’s. The traditional cementing of borate-containing liquid radioactive waste, to which the salt cake belongs, leads to a significant increase in the volume of the final product. This work describes borosilicate vitreous wasteforms developed to immobilize radioactive salt cake waste and comprises data on both glass synthesis and characterization. The composition of glass selected for the purpose of immobilisation of the salt cake radioactive waste allows to include up to 40 wt. % of the oxides contained in the salt cake and to reduce the volume of the final product by more than 2 times compared with the cement compound. The batches were melted in a cold crucible melter at 1200 Ԩ. The normalized cesium leaching rate of the vitrified wasteform product was within range 3.0·10-5 – 3.7·10-6 g/(cm2·day).
INTRODUCTION Vitrification is one of the best solutions in providing safety of nuclear waste storage, transportation and final disposal [1-3]. France, India, Japan, Russia, Slovakia, South Korea, the UK and USA have currently vitrification facilities in operation for the immobilisation of high level nuclear waste (HLW) and low and intermediate level nuclear waste (LILW), with Germany having recently completed their HLW vitrification program [1-6]. Borosilicate glasses have been universally selected as the vitreous wasteform to immobilize HLW apart from Russian Federation that continues using alkali-aluminophosphate glasses [5, 6]. However, LILW wastes such as radioactive ashes from incinerators, contaminated soils and some legacy waste streams accumulated from various nuclear development programs are preferable immobilized using specifically designed selected alumina-silicate or phosphate systems which are better suited for particular waste compositions. During operation of nuclear power plants with WWERtype (Russian-design analogue of PWR) reactors, a significant amount of operational liquid radioactive waste (LRW) is generated. This type of radioactive waste consists of saline solutions contaminated with fission products, radionuclides of corrosive origin, 121
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and various substances used to maintain the water chemistry and decontamination of equipment [1, 7, 8]. To reduce the volume of LRW at a number of operating nuclear power plants with WWER-type reactors
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