Blast & Impact Loading & Response of Structures
The dry storage systems (a.k.a. dry casks) are the most common form of spent nuclear fuel storage in the United States. Collapse or failure of dry casks due to mechanical loading is one of the main concerns of the United States Department of Energy. An explosion near a spent nuclear dry storage facility may cause catastrophic damage to dry casks and lead to leakage of radioactive waste. The explosion may be caused by terrorist attacks or malfunction in the reactor such as in the cases of Chernobyl and Fukushima. Due to lack of experimental data and extreme cost and difficulty of large-scale blast experiments on dry casks, finite element modeling is used in this study to evaluate the structural performance of vertical reinforced concrete dry casks under blast loading. To the knowledge of the authors, this is one of the very first studies on this structural typology under this type of hazard. The finite element models are developed considering the nonlinearity and strain rate effects of the materials. The conventional weapons (CONWEP) blast loading model in Abaqus/Explicit is used to induce long distance blast load on the structure with the different amount of blast charge. The structural performance of the cask is investigated in terms of stress level, material degradation, failure modes, and energy dissipation. Maximum acceleration at the fuel rods and internal deformation in the basket are estimated under different loading scenarios. Further, the critical distance and blast charge causing tip over is estimated for a free-standing cask. The results are compared with analytical solutions and empirical equations available in the literature. The finding of this study may lead to the further safety improvements of dry casks under blast loading.