γ線遮蔽用コンクリート壁に組み込む補償遮蔽体の設計手法

直スリット,段付きスリット,段付き円柱プラグ付き遮蔽壁について

抄録

A design method is described for the Fe compensational shield which is located around the air gap of a straight slit, crank slit and cylindrical crank plug in concrete shield wall against γ-radiation to compensate the lowering of shielding efficiency caused by these shield irregularities. The characteristic of this method is to compensate the lowering of shielding efficiency without increasing the concrete wall thickness and to determine the dimensions of the compensational shield using the densities of the concrete and Fe, the gap width of the irregularity and the concrete wall thickness independing on the incident γ-ray energy. The shielding calculations of the concrete wall with the Fe compensational shield have been performed using a multigroup single scattering code G33-GP with the gap widths of 0.5 cm for straight slit, and 3 cm for crank slit and cylindrical crank plug, the wall thicknesses of 75 cm and 150 cm, and various incident angles of parallel broad beam with γ-ray energies of 0.8 and 2 MeV, respectively. The calculations have showed that the shielding performance of these walls with the compensational shield is better than that of the bulk shield walls