Changes in the shielding performance of shielding containers made using heavy-weight concrete with high shielding capability against radioactivity for interim storage facilities were investigated by outdoor exposure, particularly when in contact with external water. As a result, no marked difference was found in the ratios of micropores near the surface after outdoor exposure. Water permeation tests to evaluate their shielding properties revealed that their shielding performance was equivalent to that before exposure. Within the range of this study, no marked loss in the shielding performance was observed for heavy-weight concrete.
