Spent Fuel – What Is It and How Will It be Stored

The safe, clean, temporary facility being planned by PFS will store only spent fuel from commercial nuclear power plants.Hand and Ceramic PelletThe fuel begins as enriched uranium in the form of hard ceramic pellets about 1/2-inch long and about as big around as a pencil. The pellets are put into zirconium tubes, about 12 feet long, and up to 250 of these tubes are fastened together into fuel assemblies. After the fuel assemblies have been used in the reactor for about 18 months, the fuel begins to lose its ability to produce energy efficiently. At this point, it is considered “spent.” The reactor is periodically shut down to remove the spent fuel assemblies and replace them with fresh fuel. The spent fuel is placed into a cooling pool, which is like a deep swimming pool with racks to hold the fuel assemblies. Many of the pools at the nation’s nuclear plants have up to 33 years of fuel assemblies in them and they are running out of space. After the spent fuel has been in the pool for about five years, it can be removed and placed in an above-ground dry cask storage system. Here’s how it works:

1Illustration of Step 1A stainless steel canister is placed into the cooling pool, and fuel assemblies are lifted into the basket structure that holds the assemblies in place inside the canister.  
2Illustration of Step 2The canister is lifted out of the pool and the water is drained out. The canister is back-filled with helium, an inert gas, and a 10-inch thick steel top is double welded on.  
3 Illustration of Step 3The canister is then placed into a thick steel transportation cask for shipping to the storage site. The rugged shipping containers are designed and licensed to withstand any credible accident.  
4 Illustration of Step 4At the storage site, the inner canister is lifted out of the transportation cask and placed into a concrete and steel storage cask. The loaded storage cask, weighing about 180 tons, is then placed on a concrete pad. The storage cask has a passive ventilation system; there are no mechanical systems that could fail.