Determination of linear attenuation coefficient of aggregate serpentine concrete exposed to gamma and neutron radioactive sources

Abstract

This research was designed to perform linear attenuation calculations for ordinary concrete both through simulation and experiment. The linear attenuation coefficient is an essential parameter for radiation shielding design for both source transport casks and storage bunkers. The shielding properties of concrete designed with Serpentine aggregates of different granule sizes were investigated. The simulation was performed using Radpro computer Software while the experiment involved sourcing for local Serpentine rock, crushing into four different granule sizes of 5 mm, 10 mm, 15 mm and 20 mm respectively and casting the concrete samples, exposure of the samples to gamma and neutron radioactive sources and monitoring with a radiation survey meter, sample weight measurements and concrete sample crushing using a load testing machine for determination of the concrete compressive strength. The results of the linear attenuation calculations showed that there was high consistency in the values obtained by simulation with those obtained via experiment. Very high linear attenuation property was observed when the serpentine concrete samples were exposed to a neutron source, which corroborates the fact that Serpentine rock is a Boron-rich mineral and Boron is known to have high neutron absorption property. The experimentally determined linear attenuation coefficients showed that the values at 15 mm aggregate sizes were higher than those at 5 mm, 10 mm and 15 mm sizes respectively, which demonstrates that better shielding optimization, will be obtained when the concrete cask is fabricated with 15 mm aggregate size.