WATERFORD, Conn. (AP) — It is critical to find a solution for storing the nation's spent nuclear fuel, U.S. Energy Secretary Jennifer Granholm said Friday during a visit to a nuclear power plant in Connecticut.

Granholm was invited to tour Millstone Nuclear Power Station in Waterford by Democratic U.S. Rep. Joe Courtney, the local congressional member. They are both working to change how spent nuclear fuel is stored nationwide to solve a decadeslong stalemate.

Spent fuel that was meant to be stored temporarily at current and former nuclear plant sites nationwide is piling up. Some of it dates to the 1980s.

"It is important for us as a nation to say we are finding a place to store nuclear waste in one place, so that communities are not bearing this responsibility and we are consolidating the waste," Granholm said at Millstone in front what appeared to be a concrete bunker that stores spent fuel.

There's renewed momentum to figure out a storage site, or sites, to free up the land where the waste is currently being stored and move it away from population centers, fault lines and flood plains. The Biden administration and many state officials view nuclear energy as essential to reducing greenhouse gas emissions and staving off the worst effects of a warming planet.

To responsibly use nuclear power, Courtney said, "We have to move on this issue."

The Energy Department is working to develop a process to ask communities if they are interested in storing spent nuclear fuel on an interim basis, both to make nuclear power a more sustainable option and figure out what to do with the waste.

Granholm said it's the best way to finally solve the issue. A plan to build a national storage facility northwest of Las Vegas at Yucca Mountain has been mothballed because of staunch opposition from most Nevada residents and officials.

There is roughly 89,000 metric tons of used commercial fuel at nearly 80 sites in 35 U.S. states, according to the Nuclear Energy Institute, the industry's trade association. At 20 of the sites, there's no longer an operating reactor, the institute said.

All of that spent fuel, in storage containers, could theoretically fit into a large distribution warehouse for a big box store, said Rod McCullum, the institute's senior director of decommissioning and used fuel. It could be much more efficiently managed if it was consolidated, he added.

Millstone seals its spent nuclear fuel in massive stainless steel canisters on what used to be a parking lot and keeps it in pools that cool it. There is room for 135 casks. Fifty-two casks have been installed, of which 47 are full, according to plant owner Dominion Energy.

Robert Blue, president and chief executive officer of Dominion Energy, said that while Millstone can continue safely storing the waste, it's a national issue that ought to have a national solution.

Courtney's district also includes the site of the former Connecticut Yankee Nuclear Power Plant in Haddam Neck. Connecticut Yankee closed in 1996. Spent fuel is still stored on valuable waterfront real estate.

"The frustration in Waterford and Haddam Neck, it has been off the charts," Courtney said. "People feel, you know, this was not the deal when these plants were built."

Courtney is part of a bipartisan congressional caucus working to change how spent nuclear fuel is stored. Its members believe the current system is not sustainable, particularly for sites that could be redeveloped. Many are along the coastline, in flood plains — the worst geology for spent fuel to be stranded, Courtney said.

Congress has provided about $40 million to fund the consent-based siting process that would be used to identify sites to store the nation's spent nuclear fuel, and the administration asked for $53 million more for fiscal 2023, Courtney said.

Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists, said his main concern is that planning for consolidated interim storage could undermine efforts to figure out a permanent storage repository underground.

If there's a place to ship fuel, there won't be the political momentum to site an underground repository, which is the only plausible, safe, long-term solution for this waste, he said Friday.

Millstone is one of only two commercial nuclear power plants operating in New England. One of its reactors is licensed to generate power until 2035; another is licensed until 2045.