Investigation of subcritical multiplication parameters in TRIGA Mark II accelerator driven system

Highlights: • TRIGA ADS neutron external source was numerically investigated. • Source target material, radius, position, and incident beam energy were studied. • Maximum neutron yield for W, Pb, and W–Cu targets are at radii 3.25, 3.5 and 7 cm. • Maximum source efficiency for targets at the given core is achieved at the center. • Maximum source efficiency is achieved at 40 MeV incident electron beam energy. - Abstract: The accelerator driven system (ADS) is a very interesting option to improve the safety of nuclear power reactor and for transmutation of spent fuel. The Texas phase of the reactor–accelerator coupling experiment (RACE), completed in March 2006, demonstrated the feasibility of operating a training research isotopes general atomic (TRIGA) research reactor in a subcritical configuration driven to a significant power by an electron LINAC neutron source (photoneutron). In the present study, the effects of changing the source cylindrical target material, radius, position and the electron beam energy on the final neutron production, fission probability, and the subcritical system multiplication of TRIGA Mark II research reactor, have been numerically investigated. Three target materials are used: Tungsten, Lead and Tungsten–Copper alloy, while varying the target radius from 2 to 8 cm, the source position at three locations, and the beam energy from 10 to 55 MeV. The investigation is based on the numerical calculation of the subcritical multiplication factor and the external source efficiency using Monte Carlo MCNPX code. Through the comparison of the studied cases results, the favorable target material and radius, source position, and beam energy can be obtained