MATERIALS MODIFICATIONS INC — Department of Energy SBIR Phase II: C52-40b

Description

Nuclear waste management is critical for sustaining nuclear energy as a source of low-carbon electricity. High-level waste (HLW), including spent fuels, are placed in dry canisters (casks) storage systems (DCSS) to lower the exposure risk at reactor sites. DCSS canisters are typically made of austenitic stainless steel (SS 300 series) cylinders closed using fusion welds to provide leak-tight containment of the spent fuel. With extension beyond their designed service life, chloride-induced stress corrosion cracking (CISCC) has become a significant concern to the long-term integrity of DCSS canisters.Superhydrophobic/oleophobic surface treatments can protect the DCSS from corrosion by repelling moisture and dust particles from the SS surfaces. Typical solvent-based superhydrophobic coatings have poor adhesion and durability as they are thin and easily damaged. In the Phase I project, a durable solvent-free, high-temperature stable, radiation and corrosion-resistant superhydrophobic/oleophobic coating was developed using powder coating technology. Powder coating formulations with three different superhydrophobic powders and two types of polymer binders were evaluated for protecting DCSS against corrosion, high-temperature, and radiation exposure. The coatings were optimized for high-temperature stability, radiation resistance, ease of coating and low temperature curing, and strong adhesion to the stainless-steel surface. The superhydrophobic powder coatings' corrosion protection and radiation stability were evaluated and optimized and the powder coating formulation that demonstrated promise was down- selected for further development in the Phase II project.The Phase II work will investigate the use of super repellent powder coating to repair and mitigate chloride-induced stress corrosion cracking (CISCC) in dry cask storage system (DCSS) canisters to ensure their integrity far beyond their prescribed storage period. Phase II project will conduct a viability analysis of the powder coating process to prevent, mitigate, and repair CISCC on DCSS canisters to extend canister life. In Phase II, long-term stability testing and system-level optimization will be carried out in collaboration with a DCSS manufacturer. At the end of the Phase II project, a field-repairable product for long-term storage and maintenance of Dry Storage Canisters will be available for use in spent fuel rods storage sites.Commercial Applications and Other Benefits (limited to the space provided).Large nuclear waste treatment processing plants are in operation in the United States in which low-level (LLW) and high-level waste (HLW), including spent fuel, is isolated from the biosphere for long-term safety. The proposed corrosion prevention products will help increase the lifetime of spent fuel storage tanks. The product developed could also be used for any metal container carrying hazardous materials. The superhydrophobic powder coating can also be used in outdoor furniture and equipment susceptible to corrosion due to their constant exposure to moisture.