Fusion Neutronics Experiments for Thorium Assemblies

Thorium is a fertile element that can be applied in the conceptual blanket design of a fusion-fission hybrid energy reactor, in which 232Th is mainly used to breed 233U by capture reaction. It is essential to validate 232Th nuclear data by carrying out integral fusion neutronics experiments for macroscopic thorium assemblies. The thorium assemblies with a D-T fusion neutron source consist of a polyethylene shell, depleted uranium shell, and thorium oxide cylinder. The activation of γ-ray off-line method for determining the thorium reaction rates is developed. The 232Th(n, γ), 232Th(n, f), and 232Th(n, 2n) reaction rates in the assemblies are measured by using ThO2 foils and an HPGe γ spectrometer. From 232Th reaction rates, the fuel and neutron breeding properties of thorium under different neutron spectra are obtained and compared. The leakage neutron spectra from the ThO2 cylinders are measured by a liquid scintillation detector. The experimental uncertainties are analyzed. The experiments are simulated by using the MC code with different evaluated data. The ratios of calculation to experimental values are analyzed