A Novel Cold Spray Method for Repair and Mitigation of Cracks in Spent Nuclear Fuel Storage Canisters

Dry storage of spent nuclear fuel (SNF) is canisters can be threatened by corrosion of the metallic canisters which incur substantial repair and replacement costs and logistical issues. A novel cold spray repair and mitigation approach is proposed to repair corroded SNF canisters and mitigate the corrosion threat for fabricated canisters. The proposed work utilizes a novel cold spray technique whereby a low temperature repair can take place which does not degrade the component chemistry or microstructure. In addition, no sparks are present which could cause reactions with evolved hydrogen gasses and the process can be performed remotely using robotic deposition. Lastly, complex geometries can be repaired, and the technique can also be utilized as a mitigation strategy prior to placing the canisters in the field. Phase I will see the repair of a base stainless steel alloy via cold spray of two advanced corrosion resistant alloys as well as the base stainless steel alloy. The repaired coupons will then be compared to an un-repaired coupon in terms of stress corrosion cracking, general corrosion, and mechanical property performance. Furthermore, the development of a mobile robotic repair strategy which can be performed in-situ at storage facilities will be evaluated. Successful demonstration of the cold spray repair technique for spent nuclear fuel canisters would provide a significant enhancement for the logistics of SNF storage methods where new canisters costs several million dollars. Furthermore, a valid and qualified repair technique would enable higher adoption rates of the dry cask method and provide a trusted storage method for the 50,000 metric tons of SNF in the United States. Demonstration of cold spray repair for high risk applications such as SNF storage can enable further exploration in other critical repair areas of nuclear reactors, aerospace applications, and automotive applications. If a mobile repair strategy is deemed realistic, this could further assist in the adoption of the proposed technology.