PRELIMINARY SKYSHINE CALCULATIONS FOR THE POLOIDAL DIVERTOR TOKAMAK EXPERIMENT

The Poloidal Diverter Experiment (PDX) facility at Princeton University is the first operating tokamak to require substantial radiation shielding. A calculational model has been developed to estimate the radiation dose in the PDX control room and at the site boundary due to the skyshine effect. An efficient one-dimensional method is used to compute the neutron and capture gamma leakage currents at the top surface of the PDX roof shield. This method employs an S//n calculation in slab geometry and, for the PDX, is superior to spherical models found in the literature. If certain conditions are met, the slab model provides the exact probability of leakage out the top surface of the roof for fusion source neutrons and for capture gamma rays produced in the PDX floor and roof shield. The model also provides the exact probability of leakage out the top surface of the roof for fusion source neutrons and for capture gamma rays produced in the PDX floor and roof shield. The model also provides the top roof shield surface. The actual neutron skyshine dose is computed using a Monte Carlo model. The capture gamma dose is compared using a Monte Carlo model. The capture gamma dose is computed using a simple point-kernel single-scatter method.