SHIELDING DESIGN OF A TREATMENT ROOM FOR AN ACCELERATOR-BASED EPITHERMAL NEUTRON-IRRADIATION FACILITY FOR BNCT

Protecting the facility personnel and the general public from radiatio n exposure is a primary safety concern of an accelerator-based epither mal neutron irradiation facility, This work makes an attempt at answer ing the questions ''How much?'' and ''What kind?'' of shielding will m eet the occupational limits of such a facility, Shielding effectivenes s is compared for ordinary and barytes concretes in combination with a nd without berated polyethylene. A calculational model was developed o f a treatment room, patient ''scatterer,'' and the epithermal neutron beam. The Monte Carlo code, MCNP, was used to compute the total effect ive dose equivalent rates at specific points of interest outside of th e treatment room, A conservative occupational effective dose rate limi t of 0.01 mSv h(-1) was the guideline for this study, Conservative Mon te Carlo calculations show that constructing the treatment room walls with 1.5 m of ordinary concrete, 1.2 m of barytes concrete, 1.0 m of o rdinary concrete preceded by 10 cm of 5% boron polyethylene, or 0.8 m of barytes concrete preceded by 10 cm of 5% boron-polyethylene will ad equately protect facility personnel.