Gamma-Rays and Neutrons Streaming through Air Filled Cylindrical Ducts in Water with Off-Set Alignment

Abstract

Radiation streaming effects through off-set duct was studied by systematically changing four geometrical factors in a parametric survey by calculation and experiment. The calculation were based on the ray analysis method.The four geometric parameters of the duct were (a) wall radius, (b) total length, (c) location of the off-set point, and (d) distance of off-set.The distribution of the leakage dose rate was measured in the direction across the duct outlet, parallel to that of off-set. The calculations took into account such effects as those of neutron capture r-rays, dose buildup for r-rays transmitted through shield, and photo-neutrons in the water.Satisfactory agreement was obtained between calculation and experiment for r-rays. For neutrons the agreement was not good, and the discrepancy is attributed to roughness in the approximations adopted for the calculations and to insufficient precision afforded by the method of measurement. Nevertheless it is believed that the calculations still provide results useful for obtaining a rough outline estimate of neutron streaming and which should serve for reference in shield design.