Radiation shielding design for the target area in the pre-separator of HFRS at HIAF

Abstract

High energy FRagment Separator (HFRS), an essential part of High Intensity heavy-ion Accelerator Facility (HIAF), is used to produce, separate and identify the Radioactive Ions Beams (RIBs). The target area in the pre-separator of HFRS can produce very strong secondary radiation, which seriously threatens the radiation safety of the environment, public and personnel. In this work, the FLUKA code is used to complete the radiation shielding calculation and design of the target area. Firstly, the secondary radiation produced by 25 different typical beam–target combinations are compared. The parameter of 78Kr in fast extraction mode is determined as the basis for the radiation shielding design based on its strongest secondary radiation. Then, the secondary neutron spectrum and the induced radioactivity of the production target and the beam dump are analyzed. The results show that the maximum neutron energy is close to 3 GeV, and special attention should be paid to high-energy neutrons in shielding design, as well as the maximum residual dose rates on the surface of the production target and the beam dump are 3.93 × 107μSv/h and 9.58 × 107μSv/h, respectively, after one month of continuous irradiation. Furthermore, the radiation shielding design is completed using the Q235 steel compact shielding together with the ordinary concrete and sand soil, based on the Monte Carlo simulations and the relevant dose limits. Finally, the radiation effects under this shielding scheme are analyzed. The results show that the shielding design meets the relevant design goals and can provide reliable radiation protection for the environment, public and personnel.