Masahiko Ohira

PRESENT STATUS OF THE DISTRIBUTION OF IONIZING RADIATIONS AND THE HEALTH OF PARTICIPATING WORKERS IN OUR INDUSTRIAL CIRCLE (REPORT 1)

Three hundred and seventy four industrial enterprises listed in the Department of Labor as handling ionizing radiations were investigated by means of questionnaires. Answers were received from 229 radiation handling works, involving 1, 742 workers. Number of sources were 824, among which x-ray equipments for nondestructive inspection was ranking at the top and radioactive substances, industrial gamma ray apparata, x-ray diffraction apparata, accelerators, nuclear reactors were following in the given order. According to industrial classification, the order was transportation machine makers (mainly shipbuilding), electric equipment makers, chemical industry, steel and nonsteel metal industry. Characterisitics could be admitted to their radiation sources by the sorts of enterprises. Exposure doses were investigated in those participating in one kind of radiation sources. Calculating for a year, the doses were:below (and including) 10 mrem 53.5%, under 500 mrem 33.9%, under 1000 mrem 8.3%, under 5000 mrem 3.9% and above 5000 mrem 0.4%. The measurement was taken by way of film badge method. It seldom exceeded the exposure doses given by the recommendation of ICRP. Pocket dosimeter showed almost the same, only having a tendency to show a slightly higher amount of dose compared with film badge method. Exposure dose took the order of industrial x-ray, industrial gamma ray, medical x-ray and medical gamma ray. In the scale of enterprises, there was a tendency that the exposure dose was larger in small industries.