## 1 Introduction  
It is well known that shielding of uncharged radiation (X-rays, gamma rays, and neutrons) is relatively more challenging than charged radiation (alpha and beta particles). Depending on the extent of exposure, symptoms such as vomiting, hair loss and rash can appear. Severe exposure may also lead to cancer and heart problems [1; 2; 3; 4]. To reduce such damage, time, distance, and Shielding Three factors should be considered. The exposure time to radiation should be minimized, and the intensity of radiation is inversely proportional to the square of the distance, so a safe distance from the radiation source should be maintained. Among them, shielding is the most effective in attenuating the intensity of radiation [5; 6]. In addition, for the safe isolation of radioactive waste, radiation emission should be kept to a minimum during the quarantine period. In particular, the adsorbed material used to recover radioactive ions can reduce the risk of radioactive waste, and although it is smaller in volume than the existing radioactive waste, it becomes a new radioactive waste, so an isolated storage space capable of shielding against radiation is required [7; 8; 9; 10]. As such, inorganic/organic composite materials are commonly used in ra-diation shielding [1; 2; 4; 7; 8], and as organic materials began to be considered as radiation shielding materials, interest in shielding materials in the form of organic/inorganic composite materials increased. For this purpose, thick concrete or lead is used. At this time, if the radioactive waste containing radioactive ions itself becomes a shielding material in the isolation area and attenuates the radiated radiation, it can be of great help in reducing the thickness of the shielding wall. If a structure with the purpose of recovery and isolation, such as a cesium adsorption nonwoven fabric attenuates the intensity of radiation emitted from the adsorbed radioactive ions even a little, the isolation and storage of radioactive waste can be made easier. Numerous studies related to radiation shielding materials have been conducted. For example, research on radiation shielding materials is being conducted in various ways, such as concrete [4; 9], polymer composite materials [1; 2; 8; 11], heavy metals [3; 12], and other materials [5; 7]. Most studies have focused on specific materials, and few studies have considered the structure of composite materials. However, as the use of composite materials as a radiation shielding material is on the rise, it is necessary to study the linear attenuation coefficient considering the structure of the composite material. Materials for the purpose of recovering or isolating radioactive ions, such as cesium adsorption nonwovens, are mostly composites with a large surface area and complex internal structure. It is thought that more efficient radioactive waste management will be possible if radiation shielding research considering the structure of the composite material is applied to the composite material [11; 12; 13; 14; 15]. In this study, MCNP (Monte Carlo N-Particle transport code) was used to compensate for this limitation. The interaction between particles and other materials was derived from a statistical approach and theoretically, and the possibility of radiation shielding of cesium adsorbed nonwovens through shielding simulation was reviewed. The purpose of this work is to investigate radiation shielding effectiveness of various composite materials for the 661.7 keV gamma-rays emitted by 137 Cs. It is integral to note that adsorption of cesium ions was not considered in this work. The shielding effectiveness was studied by evaluating the linear attenuation coefficient using MCNP simulations.