The federal government injected billions of gallons of radioactive and chemically hazardous liquid nuclear waste directly into the Snake River Aquifer until public pressure, led by the Alliance, halted that practice in the mid-1980s. Additionally, until 1970, the Idaho National Laboratory buried the plutonium-contaminated waste in unlined pits and trenches, and radioactive and hazardous chemical pollution from the burial grounds reached the Snake River Aquifer. The Rocky Flats Plant, a U.S. manufacturing complex that produced nuclear weapons parts near Denver, Colorado, sent hundreds of thousands of barrels, cardboard boxes, and wooden crates of plutonium-contaminated waste to Idaho (Colorado, unlike Idaho, had strict disposal requirements for such dangerous material).

Reprocessing is the must-take step between a nuclear reactor and a nuclear bomb. It is a series of chemical operations that separates plutonium and uranium from other nuclear waste contained in used fuel from nuclear power reactors (known as spent fuel). The separated material can be used to fuel reactors, but also to make nuclear weapons. Reprocessing is the source of the most dangerous nuclear waste.

The U.S. started reprocessing during the Manhattan Project to remove plutonium from irradiated reactor fuel. President George H.W. Bush stopped reprocessing in 1992. Up to that point, the reprocessing plant was the single largest air polluter at Idaho National Laboratory. Each year in the United States, nuclear power reactors produce about 2,000 tons of spent nuclear fuel. This radioactive waste, which will remain dangerous for hundreds of thousands of years, is currently stored at the reactor sites where it is generated. Spent nuclear fuel can only be disposed of in a deep geologic repository where it can be isolated from the environment, but the U.S. government has still not managed to build a permanent repository for this material.

At Idaho National Laboratory, spent fuel, much of it from the U.S. Navy, was reprocessed by dissolving it in heated, liquid acid to extract the highly-enriched uranium. The government shipped the highly-enriched uranium to Oak Ridge, Tennessee, where it was made into driver fuel for nuclear bomb production reactors in South Carolina. As a result, millions of gallons of highly radioactive liquid remained in Idaho. Much of the liquid was calcined, or dried. More than 4,000 cubic meters of calcine are stored in stainless steel and concrete bins. Before it was dried, the waste was stored in 11 300,000-gallon buried tanks. The piping around the tanks leaked, causing substantial soil pollution at the tank farm. Some of the liquid waste (about 900,000 gallons) was never calcined. The Department of Energy intended to abandon some of it in the tanks at INL and much more in tanks in Washington and South Carolina. A court challenge by the Shoshone-Bannock Tribes, the Yakama Nation, Natural Resources Defense Council, and Snake River Alliance forced improvements in that plan and ultimately led to cleaner tanks in Idaho. Almost all of the 900,000 gallons was supposed to be removed from the tanks and dried by the end of 2012 in a facility called the Integrated Waste Treatment Unit. Unfortunately, the facility has not yet successfully completed a single test run using non-radioactive, surrogate waste, and its price tag is approaching $1 billion.

The U.S. Navy tested the prototype for the reactor used in the USS Nautilus, the world’s first operational nuclear-powered submarine, in the middle of the Arco Desert. The Navy built four nuclear prototypes at the Idaho National Laboratory and used them to train thousands of navy personnel. Today, there are no reactors at the Naval Reactors Facility, but Idaho National Laboratory remains the nuclear navy’s final port of call, with all irradiated, or “spent,” fuel from naval vessels continuing to come to Idaho. All planned cleanup at the Naval Reactors Facility is complete.

INL currently stores approximately 300 metric tons of spent nuclear fuel from the U.S. Navy, domestic and foreign research reactors, commercial nuclear reactors (including the core debris from the Three Mile Island nuclear accident in 1979), and the plutonium trigger factory at Rocky Flats, Colorado (plutonium-contaminated waste sent from Rocky Flats after 1970 is stored above ground). Additionally, parts from Idaho National Laboratory’s own reactors, parts of the irradiated fuel assemblies from the nuclear navy, and the sludge from the Idaho National Laboratory’s most contaminated spent fuel storage pool remains buried.

INL has an ambitious program to exhume the plutonium-contaminated waste buried before 1970 and to stabilize and repackage the waste that was stored above ground after 1970. INL sent more than 40,000 cubic meters of the plutonium waste to the Waste Isolation Pilot Plant in New Mexico until a fire and a contamination leak in 2016 shut down that facility. After the Waste Isolation Pilot Plant reopened in 2019, INL resumed efforts to ship the waste to New Mexico. INL continues to stabilize and isolate its plutonium-contaminated waste to protect the Snake River Aquifer.