SHIELDING DESIGN FOR A PROTON MEDICAL ACCELERATOR FACILITY

Source terms and attenuation lengths for neutrons produced by 250 MeV protons on iron, copper and soft tissue, calculated with the FLUKA Mon te Carlo code, were used for the shielding calculations (walls, ceilin gs, and floors) for the National Centre for Oncological Hadrontherapy to be built in Italy, Appropriate hypotheses on the proton current, be am loss factors, duty factors, occupancy factors and use factors of th e shields were adopted, A dose equivalent limit of 1 mSv per year in t he areas where the public has access and of 2 mSv per year for facilit y personnel were assumed, Shielding requirements vary from 1.5 m to ab out 4 m of ordinary concrete, The results agree with Monte Carlo simul ations of the complete geometry of the facility obtained in a previous work, The access mazes to the treatment rooms were designed by the LC S Monte Carlo code by optimizing the length and section of their legs and their wall thicknesses with the dose equivalent limit of 2 mSv per year, fixed in the areas accessed by personnel, The resulting annual neutron dose equivalent at the maze mouth is 0.6 mSv.