Measurement and analysis of 232Th(n,2n)231Th reaction rate in the thorium oxide cylinder with a D-T neutron source

Aiming at providing reference to verify the 232Th(n,2n)231Th cross sections in different evaluated nuclear databases in the neutron energy range of 14.5-15.5 MeV, a dedicated integral experiment was carried out on a thorium cylinder setup with D-T neutrons using activation technique. 5 thorium foils were placed at 0° direction to the incident D+ beam, and the 232Th(n,2n)231Th reaction rates were determined with relative uncertainties of about 7.0%. The experiment was simulated by the MCNP code employing ENDF/B-VI, ENDF/B-VII.0, ENDF/B-VII.1, CENDL-3.1 and JENDL-4.0 libraries. The calculated 232Th(n,2n)231Th reaction rates employing JENDL-4.0 library agreed with the measured ones within experimental uncertainty, while those employing ENDF/B-VI, ENDF/B-VII.0, ENDF/B-VII.1, CENDL-3.1 libraries were all smaller than the measured ones by as much as 27.1%, 24.9%, 24.0%, 23.3% on average, respectively. The results could provide reference to the validation of 232Th(n,2n)231Th cross sections in different evaluated libraries as well as the design of thorium fuel based reactor.