Study On Key Problems Of Radiation Protection For The Radioactive Ion Beam Line HFRS At HIAF

The radioactive ion beam facility is used for generating,separating,purifying,and analyzing the radioactive ion beams?RIBs?.The RIBs can be used in many fields such as physics,material,biology,and so on.At present,there are many facilities in opera-tion,under construction or planned at home and abroad.HFRS will be built at HIAF,the RIBs are produced based on the in-flight method.The typical²³⁸U ion with 800 MeV/u in intensity and 3�10¹¹pps in intensity.It com-posed of pre-and main-separator,the primary beam impinging on the thin target to obtain the RIBs,and finishes preliminary separation in the pre-separator.Then,the fis-sion products and fragments transmit to the main-separator for further separation and purification.Moreover,the secondary target can be installed in the latter to conduct sec-ond reaction studies.Also,HFRS can run in the universal transport mode.The primary beam from BRing will be directly delivered to the SRing.There are many types of particles with high energy and high intensity can be ac-celerated in the HFRS.It has multiple operating modes,also the beam losses are widely distributed.The prompt dose rate of the secondary radiation field can reach in order of 10¹²?Sv/h,and the activation level in the surface of highly activated components?production target,beam dump?can reach in the order of 10⁶?Sv/h,which challenges the shielding design of the facility,protection of the accelerator components as well as the maintenance of devices.Firstly,the applicability of the FLUKA code in radiation protection of medium and high energy heavy ion accelerators is verified from the perspective of the neutron en-ergy spectrum,shielding calculation,and activation analysis.The results are compared with other Monte Carlo code simulations,experimental data,and empirical formula calculations.The shielding design of the pre-and the main-separator are completed,re-spectively,according to the running mode,prompt radiation source term,and the dose rate control goal.For the pre-separator,the combination of compact shielding?iron?and overall shielding?ordinary concrete?together with backfill sand and stone are adopted.While the latter,only the overall shielding?ordinary concrete?and backfill sand and stone are used.Meanwhile,the plan of protection of components is proposed,which can guide the design of beam diagnosis equipment and magnets.Besides,the primary design of the beam dump is completed by a combination of FLUKA and ANSYS pro-gram.It can lay a good technical foundation for the design and optimization of beam dump in high-power accelerator in the future.Finally,the induced radioactivity in ac-celerator components,concrete shields,cooling water,air,and environmental media is estimated.The transport plan for highly activated components is proposed,and the radiation dose assessment for staff and the public as well as environmental impact as-sessment is finished.The transport of ions with different charge states in magnetic field is simulated through the Monte Carlo codes.The influence on the distributions of radi-ation source term is analyzed,and the applicability of the two programs is discussed.The radiation protection design of the RIBs facilities is more complicated than the ordinary accelerator devices,there are rarely reported at home.The completion of this work encourages the development of the HIAF project,also provides indispensable data for the radiation protection design of HFRS and radiation environmental impact assessment of HIAF.The research methods and results in this paper can also provide a meaningful reference for similar facilities.