Measurement and Analysis of Dose Rate Distribution in the Laminated Shielding Assembly Irradiated by High Energy Photons

Abstract

Benchmark experiments on dose rate of neutrons and photons in the laminated shielding assembly have been performed at the 45 MeV electron linac facility of Hokkaido University. The accelerating energies of electron were 18, 25 and 34 MeV The shielding materials were iron and concrete. Photons were produced in the Cu target set in the direction of 0 degree to the beam line. The detectors used were CR-39 and glass-dosimeter for neutrons and photons, respectively. Analyses have also been performed by using the Monte-Carlo calculation code MCNP-5. The nuclear data libraries used for the analyses were JENDL-3.3, MCPLIB04, and EL3 for neutrons, photons, and electrons, respectively. Three different libraries reproduced by using NJOY process code from LA150, JENDL/PD-2004, and KAERI, were applied for the calculation of photo-nuclear reaction. Comparisons between experimental results and calculated ones were performed. For neutrons very good agreements were obtained at the front surface of the shielding assembly in the case of all energies, however calculational to experimental (C/E) values increased as the depth of the shielding assembly increased. On the other hand, underestimations of the calculated results for photons were observed except on the front surface. It is concluded that further investigation of production of photo-neutrons and secondary gamma-rays in the iron and concrete laminated shield would be necessary.