空隙層を含む反射・吸収効果を考慮した多層構造体による放射線遮蔽性能の向上

Abstract

A new type of radiation shield structure with narrow gaps is proposed and its shielding property is shown to be improved by taking the effects of reflection and absorption before and behind the gaps into consideration.The present shield structure consists of the multi-layered structure of shield materials. The thickness of one unit shield layer is about one mean free path of the incident X-ray in the shielding material. Three basic elements are applied to the present shield structure as follows. The first element is to equip narrow gaps between the shield layers. The second element is to use scattering/absorbing composite materials. The third element is to enclose the outside of multi-layered shield structure with absorbing materials.In the present paper the basic concept for the present shield structure is proposed as the X-ray shielding design and simplified equations are derived by considering X-ray energy flow. Using the derived equations, shielding calculations are made as to a simple multi-layered structure model. Furthermore, the fundamental X-ray penetration experiments and calculations by the Monte Carlo code EGS 4 are performed in order to prove the improvement in shielding property due to the present multi-layered structure with gaps. From these investigations, we obtained the result that the present multi-layered structure with narrow gaps can improve effectively shielding property.