[en] This work aimed at studying radon diffusion through walls of cubic cement containers containing inside radioactive waste rich in Radium-226. In addition, the effect of the wall thickness on radon exhalation and external gamma exposure were also studded. Cubic cement molds were prepared with different dimensions ranged from 5 to 11 cm containing central cubic holes to contain the radioactive materials with dimensions ranged from 2 to 7 cm. The thicknesses of the walls were varied from 1 to 4 cm. Radon exhalation was studied by placing each pre-prepared cement specimen in a tightly closed glass container (desiccators, volume 7 liters) provided with input and output gas system circulation for one week. Active method (Lucas cell) was used to measure the concentration of radon in the container. It was noticed that radon concentration increased with the increase of the radioactive materials inside the specimens. This was simply explained as it is due to the increase of the amount of radium-226 in the specimen with will definitely lead to the increase of radon production. In addition, it was noticed that radon concentration were increased by increasing the thickness of the specimen wall for fixed amount of the radioactive materials inside. This result was unexpected. Therefore, many attempts were performed to explain it. For that, the mechanism of cement solidifications and structure of cement after solidification were studied. The conditions which affect the size and number of the formed pores in the specimens were also studied assuming that increasing the wall thickness will increase porosity and lead to the increase diffusion paths. It was concluded that it is possible to use the cubic cement containers to stop gamma radiation from the radioactive materials, but it is not possible to use them to stop radon unless special arrangements are performed. (author)