Environmental radiation survey in Chernobyl area

This study was conducted to establish the technical and theoretical method of evaluating the effects of radiation on public based on the results of measurements and analysis of environmental radiation data in Chernobyl. Radiation level in the contaminated areas and the actual condition and characteristics of radiological fields were evaluated and analyzed. The method of collective dose equivalent evaluation of population was studied. This study was conducted between 1992 and 1995. The subjects were 50 houses from 7 villages (Kupovotie, Opachichi, Otashev, Illintsi, Parishev, Teremci, Ladizicchi) which are about 20 to 30 km distant from the accident reactor. Indoor γ radiation distributions were about 1/2 of that of outdoors. The outdoor radiation dose distributions of these areas were about 2 to 3 times higher than natural γ radiation level in Japan, and the indoor level, on the other hand, was almost the same. Average cumulative dose of the population (calculated by 30 days) was 67μGy in autumn and 58μGy in winter, and as for γ radiation, 42μGy in autumn and 33μGy in winter, showing difference of about 30% between autumn and winter. It is considered due to the effect of cumulative snow. Car borne survey was conducted to grasp the dose distribution of extended areas, and the following results were obtained: Highly contaminated area was admitted outside the 30 km area in the western and northern areas which were known as highly contaminated areas, and as for eastern areas, on the contrary, low dose distribution area was admitted within 30 km. (S.Y.)