Remote Repair of Sealed Containers or Dry Storage Casks Containing Used Nuclear Fuel

Currently there are three types of storage systems used to store dry spent fuel: unshielded canisters in vertically-oriented shielded overpacks or silos, unshielded canisters horizontally oriented in concrete modules, and shielded casks. Different types of damage are possible for all three systems. The health and safety of the public will be best protected if the containment and shielding surrounding spent fuel in dry storage remains intact or is restored as soon as possible following a breach. Repairing a damaged storage system if it can be done remotely should provide a significant ALARA benefit compared to removing the fuel and replacing the damaged container since it should reduce the radiation exposure of the personnel involved in the process. If the dry cask storage system were replaced instead of repaired, then there is additional cost associated with disposing of a massive component that may be highly contaminated. A repair process for a damaged system will offer cost savings and a reduction in the radioactive waste produced. The purpose of this project is to develop remotely operated equipment concepts for performing repairs on spent fuel dry storage systems. The project will include determining the types of damage that could be incurred so the types of repairs required can be defined. 3D CAD models of the various spent fuel storage containers will be created. Welding, brazing, and other repair processes will be assessed based on the results of the damage scenario study. Based on these initial studies, one or more remote repair system architectures will be conceptualized to implement the required repairs. The following considerations will be included in the concepts: heavy lifts; space and arrangement; high radiation fields; cameras, motors and sensors that can survive the environmental conditions; elevated temperatures; maintenance; and storage. These evaluations will be supplemented by a series of bench tests in which key steps in the repair processes will be physically simulated at a laboratory scale. Finally, a structured evaluation approach will be utilized to assess all of the Phase I results and rank order the alternative architectures developed for the repair system. One concept will be selected and recommended for further development during Phase II. In Phase II, the selected equipment suite will be fully developed and a prototype system will be fabricated and tested utilizing full scale non-radioactive canister mockups.