Semi-empirical formula for gamma-ray streaming through bend duct with arbitrary flexion angles

Semi-empirical formulas for the duct streaming of gamma rays are useful as ever for application to practical shielding designs. Based on the algorithm of the DIN's formula, a new semi-empirical formula has been developed. Major improvements are the re-definition of the duct leg region, introduction of the gamma-ray energy-dependent total dose albedo and formulation for the bend duct with arbitrary flexion angles. Validity of the formula was verified through benchmark analyses of gamma-ray streaming through three-legged duct with rectangular bend and the one with the flexion angle of 137 deg. (authors)