Estimate of the Shielding Parameters for the Heavy Ion Accelerator Facility by Using a Monte Carlo Simulation

For a conceptual shielding design of the Korea Rare Isotope Accelerator (KoRIA) project, the shielding parameters for the source terms and the attenuation lengths for a simple exponential formula were determined based on simulations using the PHITS Monte Carlo code. Simulations were performed for angular and energy spectra of secondary neutrons from an iron target of full stopping thickness or a thin graphite target bombarded by heavy ions of (238)U, (86)Kr, (48)Ca (200 similar to 270 MeV/u) and protons (600 MeV). Using the thus obtained neutron energy spectra for various angles, we also simulated attenuations of high-energy neutrons through 8-m-thick shields of concrete or iron. By fitting the exponential formula to the attenuation profiles, we obtained shielding parameters for various combinations of projectile, target, angle and shielding material. The parameters were summarized for a point beam loss and for a uniform beam loss along the accelerator beam line. Appropriate shielding thicknesses of concrete and iron could be estimated comparatively easily for various conditions in the heavy ion accelerator facility.