Influence of modified neutron emission spectrum on tritium production performance in blanket systems with NBI-heated deuterium plasma

Highlights: • Tritium production using DD neutrons in blanket system is studied. • The modified neutron emission spectrum due to NBI affects blanket performance. • The ⁹Be(n,2n)2α reaction rate increases about 9.0 times by the spectrum modification. • Tritium production rate is also enhanced about 4.0 %. - Abstract: In high-temperature plasma sustained by neutral beam injection heating, the emission spectrum of the neutrons produced by fusion reactions is known to have a modified Gaussian distribution. In this study, neutron transport simulation is carried out for a plasma source that emits neutrons with a modified spectrum and the influence of this modified neutron emission spectrum on the tritium production performance is investigated. The results show that in tritium production using D(d,n)³He neutrons, the rate of the ⁹Be(n,2n)2α neutron multiple reactions, which has a threshold energy of 2.0 MeV, is significantly enhanced compared with that when a source with a Gaussian neutron emission spectrum was assumed. In addition, the influence of the blanket composition on the tritium production performance is discussed.