[en] The report presents data obtained through a radioactivity survey. Various environmental and dietary materials are collected for analysis. Rain and dry fallout are collected monthly. Airborne dust is collected every three months. Service water samples are taken semiyearly at the intake of watertreatment plants and at the tap. Freshwater is taken once a year (fishing season). Soil samples are collected once a year from two layers at different depths. Sea water is collected once a year at fixed stations where the effect of terrestrial fresh water from rivers is expected to be negligible. Sea sediments are collected once a year in the same area as that for the sea water sample. A full one day ordinary diet including three meals, water and tea for five persons is collected semiyearly as a sample of 'total diet'. Polished rice is collected in producing districts and in consuming areas. Raw milk is collected in producing districts and commercial milk is purchased in consuming districts. Vegetable are collected semiyearly in producing and consuming districts. Tea samples are also collected semiyearly. Fish, shellfish and seaweeds are collected once a year. Test solutions are prepared from these samples. Strontium-90 and cesium-137 are separated and subjected to quantitative determination. Results obtained are tabulated. (N.K.)