The U.S. Department of Energy (DOE) owns the Idaho National Laboratory located near Arco, Idaho approximately 53 miles west of Idaho Falls, Idaho. Located within the 895 square mile site (almost the size of the State of Rhode Island) is the Idaho Nuclear Technology and Engineering Center (INTEC), which is operated by CH2M – WG Idaho, LLC under contract to DOE. Among the facilities at INTEC, there are several buildings or areas that are used to store spent nuclear fuel (SNF) that is owned by DOE.
- Building CPP-666, the Flourinel Dissolution Process and Fuel Storage Facility, contains 6 large wet fuel pools storing an unknown number of SNF assemblies of unknown origin (although it has been acknowledged that some naval SNF assemblies are being stored at this facility). CPP-666 is located at the south edge of the INTEC area.
- The Irradiated Fuel Storage Facility provides 636 positions for outdoor dry storage of SNF. As of the end of 2011 the facility is more than half full — the majority of the SNF having come from the decommissioned Fort St. Vrain facility in Colorado before 1991. Also being stored at the facility are SNF assemblies from foreign and domestic research reactors. Additional SNF of unknown origin is also be stored at the facility. The Irradiated Fuel Storage facility has 14 rows of storage casks, of unknown manufacture, surrounded by a security fence. The facility is located just north of CPP-666.
- Although their precise location and whether being stored wet or dry at INTEC is not known, SNF assemblies were shipped to the Idaho National Laboratory from the following two commercial nuclear power reactors and several research reactors. All this SNF is supposed to be relocated to the Idaho Spent Fuel (ISF) facility once it is built:
- 2.95 metric tons of SNF from the Peach Bottom Unit 1, a high-temperature gas-cooled reactor (HTGR) that was decommissioned in 1982.
- 18.95 metric tons of SNF from the Shippingport Atomic Power Station, a light-water breeder reactor (LWBR) that was decommissioned in 1974.
- 0.32 metric tons of SNF from various training, research and isotope reactors built by General Atomics (known as the TRIGA reactors).
- The Idaho National Laboratory also stores SNF assemblies from the naval reactors that power submarines and aircraft carriers. Storage of the majority of naval SNF occurs at the Naval Reactors Facility located approximately 6 miles north of INTEC, although some naval SNF is stored in the wet fuel pools at CPP-666 at INTEC. As of the end of 2011, there were approximately 27 metric tons of naval SNF at Idaho National Laboratory — and the inventory is growing at a rate of approximately 1 to 2 metric tons each year. Naval fuel arriving at the Idaho National Laboratory is received for wet storage in fuel pools at the Naval Reactors Facility, and later transferred to dry cask storage. As of the end of 2011, there were approximately 50 dry casks of unknown manufacture stoing an unknown number of naval SNF assemblies. The casks are stored inside a large building at the Naval Reactor Facility. By the end of 2023, all naval SNF assemblies at Idaho National Laboratory is supposed to be placed in dry casks. By 2035 it is estimated that the inventory of naval SNF at Idaho National Laboratory will grow to approximately 65 metric tons in 350 dry casks.
- An independent spent fuel storage installation (ISFSI) is used for dry storage of fuel from Three Mile Island Unit 2 (TMI-2). The TMI-2 ISFSI was licensed by the U.S. Nuclear Regulatory Commission (NRC) in March 1999. Fuel debris from the damage TMI-2 reactor core was shipped to Idaho National Laboratory between March 1999 and April 2001. The TMI-2 ISFSI uses a modified NUHOMS storage system and a specialized 12T canister, both manufactured by Transnuclear. There are 30 modules each capable of storing of up to 12 canisters; however, only 29 modules are being used and they are currently storing 177 SNF assemblies from TMI-2. The ISFSI onsists of a single concrete pad approximately 200 feet long by 100 wide, surrounded by two security fences and a security perimeter, and the modules are oriented in two separate rows.
As of the end of 2011, there were approximately 246 metric tons of commercial SNF and approximately 59 metric tons of defense SNF stored at the Idaho National Laboratory.