NAGOYA, Japan -- NGK Insulators is working to commercialize a radioactive waste treatment technology to make used resin water purifiers at nuclear power plants significantly lighter and smaller. The company hopes the method will increase underground storage capacity for radioactive wastes, as well as cut waste-management costs.
Nuclear power plants produce a range of low-level radioactive waste -- from paper towels and gloves to work clothes to contaminated rinsing water, and even air emitted through the ventilation system.
Ion-exchange resins used in the water purification system are among these wastes. Because the resin is mostly used near reactors, it is typically categorized as Level 1, the highest level among the low-level wastes.
Massive amounts of these used resins are generated at nuclear plants. They are first kept in containers for awhile, until their radioactive concentration becomes lower. Then they will be stored in metal drums and buried underground.
NGK's dry-distillation furnace, currently under development, is designed to turn the used ion-exchange resins into inorganic substances. In the process, the waste is reduced to one-50th the size or smaller. The reduced weight and volume means more resins can be stored in each drum. The method also reduces waste management costs at nuclear sites.
The dry distillation system uses an external heater to generate hot vapor at about 550 degrees inside the furnace. As the resin is tumbled with ceramic balls in the furnace, the heat helps the resin decompose into inorganic substances. The mineralizing process produces toxic gases, but the distillation system's filters keep radioactive substances from scattering outside.
A number of Japanese manufacturers are developing waste treatment systems using super-hot steam. But none such systems have actually been installed in nuclear power plants.
Ahead of rivals
NGK warns that ion-exchange resins, if disposed of without proper treatment, could release gases over the years, and possibly break the drum containers. Therefore, establishing a reliable method has been a challenge for manufacturers. NGK aims to be the first provider of such systems by making the most of its expertise in radioactive waste treatment systems.
NGK has supplied systems to more than 20 locations across the country, which employ the maker's unique incineration technologies and high-performance filters.
These include 24 vertical, cylindrical furnaces for burning combustible solids such as litter, plastics and work clothes. These are installed in domestic nuclear power plants, including the Hamaoka plant in Shizuoka Prefecture, operated by Chubu Electric Power, and Tokyo Electric Power's Kashiwazaki-Kariwa power station in Niigata Prefecture.
NGK has specialized in products in many fields, including porcelain electrical insulators for transmission towers, honeycomb ceramics for automobile, and ceramics components for semiconductor manufacturing.
The dry distillation system under development is part of its Industrial Business Process unit within the Ceramic Products group. The business unit is projected to log 25 billion yen ($218 million) in sales for the year through next March, up 5% from the year before. The manufacturer is keen to capture specific demand related to nuclear power plants, which is expected to surge in the future. The business is also considering developing facilities for decontamination after nuclear power plants are decommissioned.