Nuclear plants store decades of spent fuel on-site because there’s nowhere else to put it

Nearly every nuclear reactor that has ever operated in the United States is still holding onto the fuel it used decades ago. The federal government promised a permanent underground repository for that material more than 40 years ago, but the project never opened, so plant operators have had to improvise long-term storage on their own property instead. The result is a patchwork of steel-and-concrete storage systems parked next to reactors across the country, holding radioactive material that in some cases has been sitting in the same spot since the 1970s.

Why Spent Fuel Can’t Just Be Thrown Away

Fuel rods pulled from a reactor core remain both thermally hot and highly radioactive for years afterward, a combination described in detail in the overview of spent nuclear fuel. The fission process leaves behind isotopes that keep decaying and generating heat long after the rods stop producing usable electricity, which means the fuel has to be actively cooled and shielded rather than simply hauled away like ordinary industrial waste. That physical reality, not just politics, is why every reactor site needs a dedicated storage system from the moment it starts operating, and why that system has to keep functioning safely for decades rather than months.

The isotopes involved decay at very different rates, which is part of why there is no simple deadline after which the material becomes ordinary trash. Some of the shorter-lived byproducts fade within years, while others remain hazardous for far longer, so engineers design storage systems around the slowest-decaying components rather than an average. That is also why the fuel has to be handled behind thick shielding and monitored continuously instead of being sealed away once and forgotten, and why every storage method used at a reactor site, whether a pool or a cask, is built to be inspected and maintained indefinitely rather than treated as a one-time disposal step.

Spent Fuel Pools Are the First and Longest Stop

The first stop for freshly removed fuel is a deep, water-filled pool built into the reactor building itself. According to the Nuclear Regulatory Commission, most spent fuel in the country is still stored this way, in specially engineered pools at individual reactor sites, because water is effective at both cooling the rods and blocking radiation from escaping. Fuel typically remains in the pool for at least a year before it has cooled enough to be moved anywhere else, and many plants keep fuel there far longer than that simply because the pool has room and no other destination exists.

Dry Casks Take Over Once the Pools Fill Up

When a plant’s pool starts running out of space, operators shift older, sufficiently cooled fuel into dry cask storage, sealing it inside steel cylinders that are then reinforced with concrete or additional steel for radiation shielding. The NRC’s own history of dry cask storage traces the practice back to the late 1970s and early 1980s, when pools at many reactors began filling up faster than expected; the first dry storage system was licensed in 1986 at the Surry Nuclear Power Plant in Virginia. Those casks, grouped into what regulators call independent spent fuel storage installations, now sit in fenced concrete pads at reactor sites nationwide, including at plants that stopped generating electricity years or even decades ago.

Why Yucca Mountain Never Opened

Congress designated Yucca Mountain in Nevada as the country’s single deep geological repository for spent fuel back in the 1980s, intending it to eventually take in waste from every reactor site and end the need for on-site storage entirely. Funding and political support for the project stalled years ago, and it has never received fuel, leaving Yucca Mountain in a kind of legal limbo: it remains the only site named in federal law as a permanent disposal option, yet it is not licensed, built, or operating. That standoff is the direct reason every plant has had to keep expanding its own pools and cask pads instead of shipping waste offsite as originally planned.

The stalemate has also become a recurring legal fight rather than a settled question. Utilities that pay into the federal fund meant to cover permanent disposal have argued in court for years that the government is failing to meet its own legal obligation to take the fuel away, while Nevada officials have resisted efforts to revive the Yucca Mountain site specifically. That standoff means neither side has a clear path to resolving where the waste ultimately goes, which is part of why federal planners shifted their attention toward interim storage options that do not require reopening the Yucca Mountain fight from scratch.

The Government’s New Answer: Consolidated Interim Storage

With a permanent repository still stalled, the Department of Energy is now pursuing a different fix. U.S. reactors have generated roughly 90,000 metric tons of spent fuel since the 1950s, currently stored at more than 70 power plant sites, according to the Department of Energy’s Office of Nuclear Energy. Twenty of those sites no longer have an operating reactor at all, meaning the waste is the only reason the location still needs to be secured and monitored. The department has approved an initial step toward building a federal consolidated interim storage facility, licensed by the NRC and designed to eventually hold around 15,000 metric tons of fuel moved away from reactor sites, with the location to be chosen through a community-driven siting process rather than imposed on a particular state.

What the Delay Means for Communities Near Aging Waste

Until a consolidated site or a permanent repository actually opens, the practical situation stays the same as it has been for years: spent fuel keeps accumulating in pools and cask pads at reactor sites, including at plants that shut down long ago and communities that no longer get any electricity from the facility in exchange for hosting the waste. Utilities have to keep funding security, monitoring and maintenance for storage systems that were never meant to be permanent, and federal taxpayers continue to absorb liability tied to the government’s unmet obligation to take the fuel away. The consolidated storage project offers a potential path to finally moving material off the oldest, most exposed sites, but it remains in an early planning stage, so for now the decades-old pattern of storing spent fuel exactly where it was created continues largely unchanged.

For a decommissioned plant, that pattern can outlast the facility itself by decades. Reactor buildings, turbine halls and cooling towers can all be dismantled once a plant retires, but the fenced pad holding dry casks generally stays in place, staffed and secured, because there is still nowhere else licensed to receive the material. Nearby residents are left living beside a former power plant that, in practice, has been reduced to a single ongoing job: keeping several decades’ worth of spent fuel safely contained until the country finally builds the permanent or consolidated storage system it has been planning, on paper, since the 1980s. Until that system exists, the fuel stays exactly where it has always been, cooling in the same pools and casks, on the same small parcels of land, decades after the reactors around them stopped producing a single watt of power.

This article was produced with the assistance of AI and reviewed by Morning Overview editors.

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