A half-mile under the flat, scrubby desert in southeastern New Mexico, a warren of rectangular chambers is chiseled into a 250 million-year-old salt formation. For the last dozen years, forklifts have been filling these tombs with radioactive waste left over from the country's efforts to build nuclear bombs.
Sometime this year, the 10,000th shipment will arrive at the Waste Isolation Pilot Program, or WIPP, sealed in steel casks the size of elephants on the back of a flatbed truck hailing from one of 10 government nuclear development sites around the country.
The U.S. has been trying for decades to site and build a place much like this to hold a different type of nuclear waste _ spent nuclear fuel from the nation's commercial nuclear reactors. This effort has taken on a new urgency in the wake of the disaster at the Fukushima Dai-ichi nuclear station in Japan. Three-quarters of the 72,000 tons of spent nuclear fuel scattered across 35 states is packed into spent fuel pools likes the ones thought to have overheated and released radioactive material into the air and water around the stricken Japanese reactors.
The older fuel remains in some of those pools in part because the government has failed to fulfill a promise made 30 years ago to build a permanent disposal facility. A planned repository at Yucca Mountain, Nev., has been abandoned.
By the end of next month, a presidential commission appointed to recommend a new plan for spent nuclear fuel storage and disposal is to issue its draft report. And in the WIPP site, near Carlsbad, the commission may have found a template. An interim report it issued June 1 examines the history of efforts to build a nuclear waste repository in the U.S. and highlights WIPP as a "notable exception" to a long list of failures.
That there is no long-term plan for spent nuclear fuel in the U.S. is frustrating to utility executives, environmentalists and scientists because they say the United States has the geology, the space, and the technology to build a repository and it has been collecting money from electricity customers for nearly three decades to do so.
"I don't want to say it's a piece of cake, but it's a piece of cake," says Jim Conca, a geologist who helped design WIPP and the abandoned Yucca Mountain repository and who is now directing a nuclear waste program at the Department of Energy's Hanford site in Washington State. "You just have to let us do what we know how to do."
The problem, experts say, is political, not technical.
"The entire waste program has been pin the tail on the donkey," said Charles Forsberg, executive director of a 2010 study by the Massachusetts Institute of Technology that examined ways to handle nuclear fuel. "It doesn't matter, Republican or Democrat, the answer is, `Somewhere else.'"
WIPP has become the only long-term nuclear waste disposal site in the country in part because local officials in Carlsbad lobbied to have a repository built nearby to boost the local economy.
A 1957 report by the National Academy of Sciences recommended getting rid of waste in salt beds and domes as the "most practical immediate solution of the problem." Salt remains an ideal substance for protecting nuclear waste, experts say.
Water does not filter through salt, so it can't pick up radioactive material and spread it. The vast layers of salt underneath much of the U.S. Southwest are not prone to earthquakes. The formation near Carlsbad has been geologically stable for 250 million years.
Also, salt doesn't crack like granite. Instead, pressure makes it act like a plastic that heals its own fractures and fills voids. In New Mexico, the salt will close around the waste now being deposited at a rate of about three inches per year until it is sealed off.
"It's a big trash compactor," says Conca.
A first attempt at a salt repository in Lyons, Kan., failed in the early 1970s because of local opposition and problems including undocumented mining in the area and the site's proximity to another salt mine. But just as the Lyons project was failing, falling salt prices were hurting the economy around Carlsbad, which was dependent on salt mining. Carlsbad's mayor invited officials to consider siting the project there.
Despite local support, opposition elsewhere in the state delayed WIPP's opening 20 years. To eventually get it approved, policymakers promised New Mexico that the site would only store mid-level nuclear waste _ for example, tools, clothing or sludge contaminated with plutonium as the result of nuclear bomb-making. Lawmakers banned the site from accepting the high-level nuclear waste generated by commercial nuclear reactors, which is more radioactive, hotter and more difficult to handle.
WIPP started receiving waste in 1999. Miners have cut 56 huge rooms into the salt, arranged like a series of ladders laid on their sides. Each room has about 12,000 square feet of floor space and 13-foot-high ceilings. The rooms are separated by 30,000-square-foot pillars of salt. Each room is designed to hold the equivalent of 10,000 55-gallon drums of waste.
Most of the debris has been contaminated with plutonium and other radioactive elements, but it is not so radioactive that it is generating heat. About 5 percent of the waste to be disposed of at WIPP is hot enough that it must be handled with machines. At its most potent, it is in the lower range of the more radioactive waste like spent fuel from nuclear reactors.
"What the WIPP process affirmatively demonstrates is that with adequate patience, flexibility, and political and public support, success is possible," wrote the president's nuclear waste commission in its recent draft report.
Technical experts say that the salt formation under WIPP would be ideal for long-term disposal of spent fuel, though some worry that nearby oil and gas drilling deep below the salt beds could raise concerns. The government has 16 square miles of land in the salt flats available. When WIPP is full it will occupy one-half of one square mile.
Policymakers were led away from salt, and ultimately toward Yucca Mountain, for political and security reasons.
Spent nuclear fuel still contains huge amounts of untapped energy, but to process it into a useful form requires isolating plutonium, which is used to make nuclear weapons. The Ford and Carter administrations banned reprocessing out of concern that the plutonium could be stolen and used to make bombs.
Some then argued that the nuclear waste should be retrievable in case the nation decided someday to use the spent fuel as an energy source. One powerful proponent was former energy secretary James Schlesinger, who declined to be interviewed for this story.
The need for a site that could serve both as a dump that could be sealed off for thousands of years and an accessible storage locker made designing a facility far more difficult, and it led eventually to the troubled Yucca Mountain project. Yucca was picked in part because proposed sites in Texas and in Washington were in districts controlled by powerful politicians at the time. Texas Rep. Jim Wright was the Speaker of the House. Washington Rep. Thomas Foley was House majority leader. The legislation that led to Yucca was known as the "Screw Nevada" bill.
Yucca is near a seismically active zone, and it was designed to sit above the water table, which allows oxygen to circulate and corrode equipment. The fear is that over thousands of years, water could leak into the waste, pick up plutonium and other radioactive waste, and carry it into aquifers. Also, there is already more spent fuel in the nation's inventory than Yucca was designed to hold.
Yucca Mountain still has advocates, and the Obama administration's abandonment of it is being challenged in court.
Experts say salt is not the only option for a disposal site, and that with the right safeguards granite, shale or clay formations _ even Yucca Mountain _ could be selected. "If it's properly cited and designed there's no reason to think any of them wouldn't work," says Mark Nutt, who is working on a nuclear waste program at Argonne National Laboratory.
Regardless of what is ultimately chosen, scientists, environmentalists and utility executives are urging that something be decided soon. In a March summary of testimony it had heard, the president's commission wrote: "Several witnesses have stated that getting a disposal program back on track should be the highest priority of the commission."
And in the June interim report, the commissioners wrote: "The need for a disposal solution is, in our view, inescapable." The commissioners recommended underground storage as the "most promising and technically accepted option available."
Political and local opposition remains, as ever, daunting. During planning and design, WIPP was challenged in court by then-state Attorneys General Jeff Bingaman in 1981 and Tom Udall in 1991. Those two now represent New Mexico in the U.S. Senate.
Senate Minority Leader Harry Reid of Nevada, who helped kill the Yucca Mountain project, said in an interview he believes utilities should more aggressively move spent fuel into steel-and-concrete casks at the sites of power plants and wait for better technology to develop in the next decades. A long-term repository isn't needed, Reid said. "They're just so foolish in continually pushing that."