Management of medical radioisotope waste facility

The construction of a medical radioisotope waste facility in the Takizawa Laboratory of the Japan Radioisotope Association started in November 1985, and its trial operation started in July 1987 after carrying out cold running testing. The facility is designed for the processing of waste resulting from production and application of radioisotopes for medical use. The report outlines major features of the facility and presents some results of its trial operation. After inspection with a radioactivity measurement system, combustible solid waste is combusted in a cylindrical furnace, and waste gas generated is treated with a ceramic filter and a high-temperature HEPA filter. The capacity of the combustion system is 70 kg/h (650,000 kcal/h). Part of the waste gas is continuously sampled and passed through a filter paper, which is replaced every one week, and a GM counter and a Ge semiconductor radiation detector are used to analyze the total beta radioactivity and the concentration of beta-ray emitting nuclides, respectively. For cold running testing, model waste is used to confirm the capacity of the plant. DF performance test is carried out for the combustion, vaporization and stirring/drying systems. During the trial operation so far, the radioactivity in both waste water and waste gas from these processing facilities has been below the detection limit. (N.K.)