Radioactive-waste ocean dumping will have negligible enviromental impact

This draft report is the result of extensive studies based on the best available information in the field of oceanography, marine radiobiology and health physics. On various basic considerations, assessment was undertaken, and the following conclusion was reached. The quantity of radioactivity to be dumped at one time is assumed to be 500 Ci in the case of test dumping, and 105 Ci/year in the case of full-scale dumping. The conditions required for the dumping sea area are that the bottom water flow and upwelling amount are limited, and that the sea bottom is flat. The horizontal dispersion coefficient of 107 cm2/sec and the vertical dispersion coefficient of 2 x 102 cm2/sec are assumed. It is assumed that the radionuclides in the disposed package would leached out as soon as it reaches the sea bottom, and would not show any physicochemical behavior. Typycal radionuclides are classified into 5 groups in terms of their half lives, and their estimated concentrations at 1 km depth are tabulated. The maximum level of individual dose and the magnitude of population dose were assessed on the fishermen working in the dumping sea area, and the adults, children and infants who were expected to receive higher dose on account of the larger intake of fish products than average. The dose level given with the dose assessment model and various panamentors under the dumping conditions is much lower than natural radiation and the permissible level recommended by ICRP. (Kobatake, H.)