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

Highlights: •A dedicated internal experiment to determine the ²³²Th(n,2n) reaction rate was carried out. •The thorium cylinder device was applied in the experiment for the first time. •The simulation using MCNP code was carried out to analysis the experiment. •The JEDNL-4.0 library was proved to be more accurate in the neutron energy range of 14.5–15.5 MeV. -- Abstract: 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.