核分裂放射線によって誘発される末しょう血リンパ球染色体異常発生率 臨界事故時の生物学的線量計測

Abstract

For the purpose of utilizing radiation-induced chromosome aberrations in human peripheral blood lymphocytes as a means of dose evaluation in a criticality accident, a study was made of the relationship between fission neutron+gamma dose and the chromosome aberrations. Human peripheral blood lymphocytes were exposed in vitro to fission neutrons+gamma rays at Japan Research Reactor No. 4 for 5, 10, 20, 30, or 40min at 200kW. The cells were observed at their first mitotic division stage in culture.The frequency of the chromosome aberrations per cell, Y, was expressed as a power function of exposure time in minutes, t, as follows: Y=0.0018t1.12.On the assumption that there was no mutual interaction between chromosome aberrations induced by the neutrons and those by gamma rays and that there was similarity of the effects of the gamma rays produced in fissions and those of Co-60 gamma ays, estimation was made of contribution of the gamma rays to total yields. However, there was a contradiction that the contribution of gamma rays exceeded the total yield.