DT Neutronics Benchmark Experiment on Lead at JAEA-FNS

Abstract

Lead is one of the most important candidate materials for nuclear fusion reactor blankets. We have carried out an integral benchmark experiment on lead at the DT neutron source facility of JAEA, FNS. A cubic lead assembly on a side of 45.3 cm was set up and was irradiated with the DT neutron source. Reaction rates of the Al(n,α)Na, Nb(n, 2n)Nb, Zr(n, 2n)Zr, and In(n, n′)115mIn reactions and neutron spectra above 2 MeV were measured inside the assembly with activation foil and a small NE213 spectrometer, respectively. A Monte Carlo code, MCNP5, was adopted to calculate the reaction rates and neutron spectra. The latest nuclear data libraries, JENDL-3.3 ENDF/B-VII.0, JEFF-3.1 and FENDL-2.1, were used in the calculation. The calculation results with the three libraries except for JENDL-3.3 agreed with the measured reaction rates and neutron spectra. On the other hand, that with JENDL-3.3 underestimated the measured ones with the depth. We found out that the inappropriate evaluation of the (n, 2n), elastic scattering and inelastic scattering reactions in the lead isotopes of JENDL-3.3 caused the disagreements