Modelling of the Production of Source Neutrons from Low-Voltage Accelerated Deuterons on Titanium-Tritium Targets

Fast quasi-monoenergetic neutrons can be produced by acceleratingcharged deuterons on tritium solid targets. Benchmark experimentswere performed in many laboratories with intense D-T neutronsources. The aim is to validate the computational models andnuclear data for fusion applications. The detailed information onthe neutron source term is highly important for the benchmarkanalyses. At present, the MCNP family of codes cannot explicitlymodel the D-T reaction for Deuterons in the KeV energy range. Thephysics for the D-T neutron production was modelled at ENEA(Italy) in the SOURCE and SRCDX subroutines to compile with theMCNP source code. Some improvements to the original subroutineswere introduced. The differential cross-sections for the D-Treaction from the ENDF/B-VII library were built into the code. Therelativistic approach was implemented for neutron kinematics. Thenew D-T neutron source model was applied to the MCNP5 simulationof the tungsten integral experiment performed at the OKTAVIANfacility. The uncertainty associated with the realistic D-Treactions was separated from the total uncertainty of the sourceterm. The outcome of the benchmark analysis was an improvement inthe quality of the computational model of the experiment