Material Durability Performance of Reinforced Concrete Dry Cask Storage Systems for Nuclear Waste

Abstract

Dry cask storage systems (DCSS) are currently the only means of waste nuclear storage in the United States. Although these structures are designed for temporary use with an intended service-life of 20 years, in the absence of a long-term storage solution, it is highly likely that DCSS will be used for a period exceeding 50 years. Approximately 40% of all the DCSS employ a reinforced concrete (RC) outerpack for protecting nuclear waste against manmade and natural hazards as well as for radiation shielding. As such, it is essential to investigate the durability performance of the RC under environmental and mechanical conditions specific to DCSS. One of the main durability issues is identified as the corrosion of reinforcement. High temperature from the nuclear waste, ambient humidity and potential airborne chloride at the storage site increases the risk of corrosion in these structures. In this paper, two different mixtures are studied, a control mixture meeting the current specifications for DCSS and a mixture with added calcium chloride. The second mixture is intended to accelerate the corrosion for the two-year period of the experimental program. As a part of an ongoing experimental program, specimens are being tested at different ages to measure compressive, tensile and flexural strength, and mass loss due to corrosion, among others. It is expected that the results from this experimental program will help understand the long term behavior of RC DCSS.