An Evaluation of Two Aggregates for Use in a Concrete Reactor Shield

The dose buildup factors (up to 20 mfp) for gamma rays from a point isotropic ⁶⁰Co source penetrating multilayered concrete slabs using Cox's Bazar and Sylhet sands have been measured. The instantaneous relaxation lengths (up to 20 mfp) have also been measured for both types of concrete slabs. Some physical properties of concrete blocks of magnetite, Sylhet sand, and a mixture of both types of sand have been measured. Results obtained show that the buildup factors for Sylhet sand slabs increase more rapidly than those of magnetite slabs. The buildup factors for Sylhet sand concrete (ordinary concrete) have been compared with the results obtained from the Berger formula at an energy of 1.25 MeV. The transmission is higher through slabs of Sylhet sand than those of magnetite. Comparing all properties among magnetite slabs, Sylhet sand slabs, and a mixture of magnetite and Sylhet sand slabs, it is found that slabs of a mixture of both sands are more effective for reactor shielding than those comprised of only one of the components.