Experimental and simulative studies of thorium fission rates on thorium oxide/depleted uranium cylinders with D-T neutrons

Aiming at validating thorium fission parameters and the code used in the conceptual design of fusion-fission hybrid energy reactor, an integral experiment on thorium oxide/depleted uranium cylinder assemblies for thorium fission rate has been carried out with D-T neutrons. Thorium fission rate in the axial direction of the assemblies was obtained by adopting the activation method, and the experimental uncertainties were 5.6–5.9%. MCNP simulation employing ENDF/B-VII.0 and ENDF/B-VII.1 library data were 5%–21% smaller than experimental ones. The influence of the polyethylene oxide (PEO) in the thorium oxide cylinders, evaluated by MCNP simulation employing ENDF/B-VII.0 library data, is negligible in the present thorium/uranium assemblies under the measured level. The difference between the present results and our previous ones was also analyzed. The stage experimental results could provide reference for the evaluation of neutron-induced thorium fission cross section, and should be considered in the margin of the conceptual design of FFHER.