Radiation shielding of two-region neutron-source storage vessel

Problems of radiation shielding are studied on a two-region vessel made of paraffin and lead. This vessel is designed to store some radioisotope neutron sources such as Ra-Be and Am-Be. The radiation to be considered includes capture and direct gamma-rays and source neutrons. To solve the problem by practical calculation, a spherical shell model is assumed; the actual cubic vessel is replaced by an equivalent spherical shell having the same volume. The total equivalent-dose rate at the outer surface of the shell obtained from such calculation is compared with the experimental one. This comparison indicates that the model is adequate for predicting the shielding ability of the vessel with minor improvements. The maximum radioactive storage capacity of the vessel for Ra-Be and Am-Be sources is also discussed. (auth.)