An approach of radiation streaming safety evaluation for complex shaped structures

Radiation shielding structures at large facilities are classified into the bulk part and the complex shaped structure part. In the latter case, radiation streaming strongly depends on the shape and location of unfilled space. Following the experimental research program carried out for this purpose by the group of the present authors, four problems have been pointed out to be solved. Since there had been few reliable calculation formulae and data base for them, the research program tiltled as this report was started to make out systematic data base of spatial distribution of radiation dose for each problem mentioned there and to develop simple approaches to evaluate radiation dose using them. In last year, coding of the simple calculation method for the secondary gamma-rays streaming through the complex shaped structure was worked out and the spatial distribution of the streaming radiation behind a shielding wall was calculated. A simple code, which can be operated on Windows, has been developed to calculate the streaming radiation dose through a cylindrical duct and its evaluation was performed as well. The accuracy of the calculation code is to be tested in future. (S. Funahashi)