Assessment of gamma radiation shielding properties of concrete containers containing recycled coarse aggregates

This paper presents an assessment of gamma radiation shielding performance, specifically in terms of surface dose rate, of concrete containing virgin and recycled coarse aggregates (RCA) to be used for a transportable concrete container for radioactive waste. In order to evaluate radiation shielding performance of the transportable concrete container a numerical simulation method is performed using Monte Carlo N-particle version 6.1 (MCNP6.1). Prior to evaluating radiation shielding performance of the transportable concrete containers, radiation shielding properties of four different concrete mixtures which have two different compressive strengths, 40 and 70 MPa, containing natural coarse aggregate (NCA) and recycled coarse aggregate (RCA), respectively, are assessed using experimental and numerical simulation methods in terms of linear attenuation coefficient (μ) to verify the reliability of the numerical simulation method. Density, compressive strength, and static modulus of elasticity tests are conducted to determine the parameters for transportable concrete container design. Based on the physical properties of concrete a transportable concrete container is designed. In order to assess the radiation shielding with respect to the maximum surface dose rate of the concrete containers, three different radioactive wastes are assumed to be loaded in the containers with metal drums and radiation shielding analysis is carried out using MCNP6 simulation code for the four different concrete containers, comparing with the existing carbon steel container. It was found that the results from numerical simulation are in good agreement with the experimentally determined results. In terms of the maximum surface dose rate, all concrete containers showed considerably lower surface dose rate than the existing carbon steel container.