Shielding Calculations for the Design of Neutron Radiography Facility Around Parr

摘要

Shielding calculations for neutron radiography facility, proposed to be established around PARR have been carried out using two group diffusion theory and other shielding formulae. A 65 cm thick graphite block is provided as a source block. A divergent beam collimator with a collimating ratio of 127 and source size 16.2 mm theta has been designed to provide more imaging area. 25 cm thick shield of bismuth is provided to reduce high energy gamma radiation and to slow down fast neutrons. The neutron to gamma ratio is 2.95 x 107 sq cm/m Rem. Beam shutter is 39.6 cm thick and comprises of B4C, paraffin wax, aluminum, lead and steel as shielding materials for neutron and gamma rays. The front and side wall thicknesses of beam trap are 39.6 cm and 20 cm respectively. The front and side wall thicknesses of enclosure are 50 cm and 30 cm respectively. The expected dose rate in the beam and lateral direction of the radiation enclosure is 0.6 and 0.02 mRem/hr respectively.