Internal Dosimetry of Spontaneously Fissioning Nuclides

Abstract

A general method has been developed which allows one to estimate the radiation dose to various organs of a homogeneous reference man phantom for the case of internally deposited spontaneously fissioning nuclides. Spontaneously fissioning nuclides are bone seekers but the GI tract, lungs, liver and genetic organs are also considered in this study. The doses due to neutrons, prompt and delayed gamma rays, beta particles, and recoil fragments are each considered separately. The known calculated neutron dose distribution about a point-isotropic 252Cf source is used to obtain the average dose, by Monte Carlo techniques, to any organ for the source uniformly distributed in a specified organ. The prompt and delayed gamma spectra associated with the fission of 236U are used in conjunction with known specific absorbed fractions in order to obtain dose estimates. The fission of 236U is also used as a prototype for beta dosimetry calculations. For neutron, gamma and beta radiation, methods are discussed which allow one to obtain corresponding results for any spontaneously fissioning nuclide.