Safely Transferring Used Nuclear Fuel from Wet to Dry Storage

Safely Transferring Used Nuclear Fuel from Wet to Dry Storage

Loading Fuel Assemblies into Canister

A robust, stainless steel alloy canister is placed into the HI-TRAC transfer cask and lowered into the spent fuel pool. Fuel assemblies are loaded into the canister, which is then welded shut. All water is pumped out of the canister, and helium is injected to ensure a dry interior.

HI-TRAC on Transport Vehicle

The HI-TRAC is transferred from the spent fuel handling building to the dry cask storage location via a large flat transport vehicle.

HI-TRAC on the Vertical Cask Transporter

The HI-TRAC is then secured onto a loading device called a vertical cask transporter which carries it to a specific location on the pad, where the canister is safely lowered out of the HI-TRAC and into the cavity enclosure container. Finally, a 35,000 pound lid is placed securely on top. Throughout the entire loading and transport process, the canister and HI-TRAC are secured by seismically qualified restraints.

Key Facts:

  • Canisters are 5/8” thick, stainless steel alloy, weigh approximately 40,000 pounds and hold up to 37 fuel assemblies.
  • Transfer casks are made of lead and steel.
  • The newly expanded dry cask storage facility contains more than 920 tons of reinforced steel rebar and more than 18,000 cubic yards of concrete.
  • San Onofre’s dry cask storage systems exceed California earthquake requirements and are designed to withstand extreme conditions such as fires, projectiles, flooding and tsunamis.
  • Dry storage is reviewed and licensed by the U.S. Nuclear Regulatory Commission, and has been safely used in the United States for more than three decades. SCE has stored used fuel in dry storage at San Onofre since 2003.
  • Dry fuel storage is a passive cooling system with no moving parts. The fuel is kept cool by air entering vents in the structure and circulating around the outside of the steel canister.
  • SCE is required by the NRC to safely store used nuclear fuel until the federal government meets its legal obligation to remove it. Dry cask storage renders the fuel ready to transport when an off-site location is ready.