Benchmark experiments on breeding properties of thorium

Thorium is a fertile element that can be applied in the conceptual blanket design of a fusion-fission hybrid reactor. It is essential to validate 232Th nuclear data and obtain the breeding properties of macroscopic thorium assemblies by conducting integral neutronics benchmark experiments. The thorium assemblies with a D-T fusion neutron source consist of a polyethylene shell, depleted uranium shell, and thorium oxide powder cylinder. The 232Th (n, γ), 232Th (n, f), and 232Th (n, 2n) reaction rates in the assemblies are measured by ThO2 foil activation technique. The experimental uncertainties are about 3.1% for 232Th capture rates, 5.3–5.5% for 232Th fission rates, and 6.8–7.0% for 232Th (n, 2n) reaction rates. From 232Th reaction rates, the fuel and neutron breeding properties of thorium under different neutron spectra are obtained and compared. The experiments are simulated by using the MC code with different evaluated data. The ratios of calculation to experimental values for the reaction rates are analyzed.