Benchmark experiments on breeding properties of thorium

Highlights: • To validate Th nuclear data, benchmark experiments for Th assemblies are performed. • ²³²Th capture, fission, and (n,2n) reaction rates are measured using ThO₂ foils. • Experiments are simulated by using the MCNP code with different evaluated data. • Fuel and neutron breeding properties of thorium are obtained and compared. - Abstract: 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.