Xcel Energy is planning to update its spent fuel storage technology for the final nine casks that it will fill at the Prairie Island Nuclear Generating Plant.
According to the U.S. Nuclear Regulatory Commission, there are currently two main ways that spent nuclear fuel is stored in the country. The first is spent fuel pools, where used fuel is cooled and stored at least 20 feet underwater. The second storage option is dry casks.
Xcel currently uses a vertical canister system on Prairie Island where individual canisters hold the fuel. The proposal is to use a horizontal, concrete vault system moving forward. In this design, the radioactive waste is placed into a steel canister with two welded closure lids and then the canister is sealed into the vault.
Xcel Energy Nuclear Engineer Jon Kapitz presented the new storage plan to the Red Wing City Council on Monday, Dec. 13.
He said of the current storage system, “We’re really the only site left in the U.S. that is using this type of model casks. We picked it in ‘89, it’s a very good design, it's served us well, but things have just changed in the last 30 years.”
Meanwhile, the canisters used for Xcel’s current storage are becoming more expensive and they are not licensed for other plants in the country. The horizontal storage system can, however, be held at any nuclear plant in the U.S.
The ability to move spent fuel is important as numerous municipalities hope to have spent fuel removed from their communities.
The Prairie Island Indian Community, which shares the island with the nuclear facility, states on its website, “The Prairie Island Indian Community calls on the federal government to keep its promise to remove nuclear waste from Prairie Island and the 65 nuclear power plant sites around the country by creating one or more deep geologic repositories to store and dispose of nuclear waste.”
This statement refers to the Nuclear Waste Policy Act, which was signed in 1982. The EPA summarizes the act as supporting “the use of deep geologic repositories for the safe storage and/or disposal of radioactive waste. The act establishes procedures to evaluate and select sites for geologic repositories and for the interaction of state and federal governments. It also provides a timetable of key milestones the federal agencies must meet in carrying out the program.”
In 1987, the act was amended to designate Yucca Mountain in Nevada as the location to consider for the storage of radioactive waste. However, this has not been achieved due to a variety of factors, most notably politics and pushback from Nevadans.
Currently, there is not a plan for moving spent fuel off of Prairie Island. However, if it ever does need to be moved, both the current and proposed types of casks could be transported.
The potential difficulty is the fact that the current cask cannot be stored at most spent fuel sites. At the moment, Xcel’s plan is to keep the current casks as is and only use the horizontal system for the final nine casks.
In total, Xcel is allowed only to store 64 casks of spent nuclear fuel on Prairie Island. The Minnesota Commerce Department explains that originally, the nuclear plant was going to have 35 casks. However, in 2008 Xcel Energy applied for and was granted an extension of the plant, which is currently slated to be open until 2034. In order to ensure all spent fuel could be stored on site, the Nuclear Regulatory Commission approved to expand the limit of 35 casks to 64 casks.
State review schedule
Xcel Energy cannot make the decision about spent fuel casks on its own. Ultimately, the Public Utilities Commission will make a decision on Xcel’s plan for the new spent fuel storage. The current timeline is:
September 2021: Xcel request filed with commission
January 2022: Draft Supplemental Environmental Impact Statement issued
February. 2022: Public comment period
March 2022: Final Supplemental Environmental Impact Statement issued
March/April 2022: Public Utilities Commission decision on Xcel request