Application of a Simple Evaluation Method for Gamma-Ray Streaming to Multi-Bent Ducts Taking Account of Only Components Passing through the Duct

A simplified formula for γ-ray streaming through ducts is devised to apply to multi-bent ducts by optics analogy with considering only components passing through the duct without enormous preparatory calculations. Dose rates estimated by the formula are compared with experimental values in two types of two-stage bent ducts for about 1 MeV energetic γ-ray source. Regarding the two-stage, 45-degree bent duct with a diameter of 15 cm, estimated dose rates at the positions of the bend points and the exit agree with the experimental values within 30% and a factor of 2, respectively. Regarding the two-stage, 90-degree bent square duct with a 1.8 m side, estimated dose rates at the positions of the bend points and the exit agree with the experimental values within 30%. From these results, it is concluded that the formula is applicable to the midway in shielding design.