Development of simple evaluation method for dust streaming

A simple formula for radiation streaming through bent ducts is derived by optics analogy with considering only components passing through the duct not required for enormous preparatory calculations. Dose rates estimated by the derived formula are compared with experimental values in two types of two-stage bent ducts for gamma-ray source and four types of one-stage bent ducts for 14 MeV neutron source. Regarding the two-stage, 45-degree bent duct with a diameter of 15cm, 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 1.8m side, estimated dose rates at the positions of the bend points and the exit agree with the experimental values within 30%. For 90-degree one-stage bent square ducts with 10cm, 20cm and 40cm sides in iron and polyethylene shields with 14 MeV neutron source, dose rates by the formula agree with experimental values within factor 3 at the exit. From these results, it is concluded that the derived formula is applicable to the midway in shielding design. (author)