CONTAMINATION MODE DISCRIMINATING INSTRUMENT

摘要

PURPOSE:To enable whether the contamination mode of a radioactive waste is of a surface contaminant or of a radioactive matter to be accurately discriminated by comparing a difference between the ratios of measured beta ray values to measured gamma ray values obtained by measuring objects to be measured by radiation measuring means with a reference value. CONSTITUTION:beta rays and gamma rays radiated from an object to be measured 1 being conveyed by a conveyor line 7 are measured by beta ray detectors 4a-4d and gamma ray detectors 5a-5b on radiation detecting means 2a-2d, respectively. Then, measured results are fed to arithmetic means 3 and the ratios of measured betaby values to measured gamma ray values for every measuring means 2a-2d are calculated. A difference between the ratios obtained by two pairs of the means (2a and 2b) and (2c and 2d) respectively opposing to each other is calculated and compared with a reference value. The object to be measured can be accurately judged to be a surface contamination when the absolute value of the difference is larger than the reference value while it is judged as a radioactive matter when the value is not larger than the reference value.