The lack of hierarchy and multiple restrictions by the radiation protection laws in Japan, causes multiple dose records of individual and scattering dose records. To solve the problem, the National Radiation Dose Registration Systems was proposed already by Atomic Energy Commission about 40 years ago. But only one radiation dose registration system is partly effective, which was applied for workers in nuclear power plants. This paper reports political problems in the system of radiation protection laws of Japan, and proposes the new national radiation dose registration systems which will be able to have a function of supplementation of quality assurance of radiation protection laws.

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The international program, known as the EMRAS (Environmental Modeling for Radiation Safety) project was carried out in 2003-2007. “The working group for modelling of tritium and carbon-14 transfer to biota and man” took an active part in the EMRAS by presenting the eight scenarios for the purpose of the validation of the environmental tritium model. Three scenarios were concerned about uptake and depuration of tritium by bivalves and various biological species in a steady state lake. Two scenarios dealt with tritium uptake of soybean and pine tree, other two did pig metabolism and various products from a farm land. One scenario was designed to estimate human dose exposed by a hypothetical shot of tritium release in the atmosphere. OBT definition and revision of parameter values in the Handbook, IAEA-TRS No. 364 were also carried out.

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As part of the environmental radiation monitoring around the nuclear fuel cycle facilities constructed in Rokkasho-mura, we are carrying out continuous measurements of gross α and gross β radioactivities in air dust samples. Considering there measuring conditions, it is suggested that ²¹⁰Po and ²¹⁰Bi mainly contribute to gross α and gross β, respectively. The higher concentration of gross β radioactivity was observed during fall and winter. But then gross α radioactivity lowered during winter, and fluctuated on spring and fall. It is suggested that surface soils are one of major origins of gross α radioactivity, because ²¹⁰Po/²¹⁰Pb ratio in the soil is higher than the ratio in the air and the ground is covered with snow in winter. Large peaks of gross a radioactivity and α/β radioactivity ratio were observed on May 2003. Satellite imageries showed forest fires around Lake Baikal in this period. We confirmed that the air mass passed the vicinity of Lake Baikal and flowed in Rokkasho-mura by backward trajectories. There was a positive correlation between gross α radioactivity and the frequency of air mass traveling from the vicinity of Lake Baikal to Rokkasho-mura. The result suggested that the large peaks of the concentration of gross α radioactivity and α/β radioactivity ratio were caused by the forest fire in Russia.

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