Dose Estimations of Fast Neutrons from a Nuclear Reactor by Micronuclear Yields in Onion Seedlings

抄録

Irradiations of onion seedlings with fission neutrons from bare, Pb-moderated, and Fe-moderated ²⁵²Cf sources induced micronuclei in the root-tip cells at similar rates. The rate per cGy averaged for the three sources, <b_n>, was 19 times higher than rate induced by ⁶⁰Co γ-rays. When neutron doses, D_n, were estimated from frequencies of micronuclei induced in onion seedlings after exposure to neutron- γ mixed radiation from a 1 W nuclear reactor, using the reciprocal of <b_n> as conversion factor, resulting D_n values agreed within 10% with doses measured with paired ionizing chambers. This excellent agreement was achieved by the high sensitivity of the onion system to fast neutrons relative to γ-rays and the high contribution of fast neutrons to the total dose of mixed radiation in the reactor's field.