Y.Maeda 1 , S.Osaki 2
1 Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka, Japan
2 Radioisotope Center, Kyushu University, Fukuoka, Japan
The environmental distribution of radionuclides, released from nuclear facilities and other sources, and the principles of the countermeasures for radiation protection of the public and workers are discussed. The concentration levels of radionuclides in various aquatic and terrestrial environments, and the exposure levels of the population due to the various sources of radiation (natural and artificial radionuclides, cosmic radiation, diagnostic medical examinations, atmospheric nuclear tests etc.) are presented.
The methods for the collection and pretreatment of environmental and dietary materials is described in several papers (RSDJ 2002). To keep reliable data that can be compared with other measurement methods, samples collected by a standardized sampling method and prepared with a standardized pretreatment are necessary. Measurement of the radioactivity of ?-ray emitters is carried out by ? spectrometry, using a high-resolution germanium detector with a lead shield. Spectra are analyzed using a ?-spectrum analysis program to calibrate counting efficiency, energy and counting geometry for radioactive standards. Radioactivity of ?-ray emitters is measured using a low-background anti-coincidence ? counter. NBS calibration standards for ?-ray and ?-ray emitters are available for detected nuclides. Accelerator mass spectrometry (AMS) is useful to measure extremely low-abundance nuclides (isotope ratio of 10 ?12 to 10 ?16 relative to its stable isotope), such as 10Be, 14C, 26
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