I have posted about the process of vitrification in the past. Radioactive waste is mixed with sand and other chemicals and then the mixture is subjected to high temperature that melts it. After it solidifies, a glass cylinder is the result. This can be buried in a geological repository. The reason for vitrification is to prevent the possible leaching of radioactive materials out of the storage area by the flow of ground water. There are a variety of specific technologies and chemical mixture for vitrification. In addition to vitrification, there are also other approaches to embedding radioactive waste in some sort of solid material other than glass to immobilize it and prevent leaching. There is a new system which embeds the waste in synthetic rock being developed in Australia.
The Australian Nuclear Science and Technology Organization (ANSTO) "is Australia's national nuclear organization and the centre of Australian nuclear expertise. The Australian Nuclear Science and Technology Organization Act 1987 prescribes its general purpose. The purpose is translated into action through corporate drivers of vision, mission and strategic goals." One of the missions of ANSTO is "to operate nuclear science and technology based facilities, for the benefit of industry and the Australian and international research community."
In 2012, plans were announced for a nuclear medicine plant and a pilot plant for radioactive waste disposal at the ANSTO Lucan Heights site near Sydney. These two plants are referred to as the ANSTO Nuclear Medicine project. A molybdenum-99 plant and a waste disposal plant are under construction and both should be completed by the end of 2016. The idea is for the waste treatment facility to process waste from the manufacture of the molybdenum-99. The waste will be mixed with chemicals and baked into what is being called synthetic rock or Synroc.
The first step of the Synroc process consists of mixing the radioactive waste with chemical additives that result in a thick liquid. Then the liquid is dried and a granular powder is left. The powder is heated and then put into cans. The cans are put into a device that subjects them to intense heat and pressure which fuses the powder in a solid and causes the can to contract around the cylinder of solidified waste. One of the benefits of the Synroc process is to significantly reduce the volume of radioactive waste.
ANSTO technicians are working on demonstration models of different stages of the Synroc process. As stages are successfully embodied in working hardware, additional stages will be added. Ultimately, when the entire chain of hardware has been developed that can carry out all of the stages of the process, an industrial facility will be constructed based on the completed demonstration design. The creation of the demonstration system should help to answer engineering design challenges before the actual working plant is constructed.
Australia is in the process of siting, licensing and constructing a national facility for the management of radioactive waste. Following the completion of the facility, the Synroc cans created at the Lucas Heights facility from the molybdenum-99 production will be shipped to the disposal facility.
Synroc waste can:
