Vitrification processes for low, intermediate radioactive and mixed wastes

We describe Scientific and Industrial Association (SIA) RADON's experience in developing and implementing radioactive waste vitrification technologies covering low, intermediate and high level wastes. RADON is a company involved with the Administration in Moscow responsible for management of radioactive waste in Central Russia. It started its activity in the field of waste vitrification process development in the middle of the 1970s. The first unit implemented at RADON to vitrify low and intermediate level wastes from nuclear power plants in a borosilicate glass was a Joule heated ceramic melter based plant with waste capacity of up to 10 l/h and glass production rate of up to 10 kg/h. The plant was improved and melter was upgraded step-by-step, eventually resulting in a semi industrial scale melter with a waste capacity of up to 50 llh and glass production rate of up to 35 kg/h. In the middle of the 1980s development of cold crucible melting processes was started and various cold crucibles for treatment of different liquid and solid wastes were designed. Since 1991, design and construction of a full scale liquid waste vitrification plant has been undertaken. The plant consists of waste preparation, batch preparation and feeding, batch melting, glass annealing units, off gas, water and energy supply systems. The melting unit is equipped with three cold crucible's each with glass production rate of up to 25 kg/h. Other vitrification systems for the conditioning of liquid and solid wastes (incinerator ash, ion exchange resins, spent catalysts, etc) based on cold crucibles and plasma melters have been developed and tested. RADON is carrying out an extended programme of long term testing of real immobilised radioactive wastes under natural conditions.