The New Mexico dump which holds the nation's dirtiest laundry from nearly 70 years of nuclear weapons production was supposed to be a an accident-proof underground vault that would entomb radioactive waste in a 2,000-foot thick layer of salt for at least 10,000 years.

It's not working out that way. And like most things related to nuclear waste, it looks like the news is going to get worse—and a hell of a lot more expensive—before it gets any better.

Now, officials with the U.S. Department of Energy say that it appears a second drum of plutonium waste has the potential of bursting—if it hasn't already—at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, possibly contributing to a leak from another ruptured drum that left 21 workers exposed to small amounts of radiation earlier this year.

On February 14, a drum of plutonium-contaminated waste from Los Alamos National Laboratory overheated and burst open from an apparent chemical reaction between bags of nitric acid (used in the plutonium-extraction process), organic matter and lead—sending radiation up a half-mile long air vent to the surface, where it contaminated the workers.

DOE official Joe Franco told state and local officials at a hearing in Carlsbad on Thursday that the second drum was located in an underground waste panel separate from the original ruptured drum. The agency was expected to release details about their plans to cleanup the facility, but the full plan was still under review by officials in Washington.

Investigators with LANL say that they still haven't been able to duplicate the exact chemical reaction that led to the rupture, although they say it may have been caused by a discarded glove box. According to the Carlsbad Current-Argus, investigators say that the two drums contained material dating back to 1985 from the now-defunct Rocky Flats Weapons Plant near Denver.

The two drums contain transuranic (i.e. any elements with an atomic weight heavier than uranium—in this instance plutonium) waste material that was originally stored in one drum at the Colorado facility. Investigators say that temperatures inside the waste drums would have to hit 572 to 662 degrees Fahrenheit to cause a chemical reaction like the one that caused the leaks.

Investigators testified at the public hearing the cardboard glove box contained lead—which reacts with nitric acid at a lower temperature.

That reaction could have heated the drum up to a point where it would then react with kitty litter that was used as an organic absorbent in the drum, causing it to split open from the heat and leak out the toxic radioactive filling.

The contamination was not expected to have any impact on the health of the exposed workers—of course nobody expected the supposedly radiation leak-proof dump in the Chihuahuan Desert to fail as quickly as it did, either.

According to former DOE officials, the facility was designed so that a release of any radioactivity into the atmosphere was supposed to be a 1-in-every-200,000 year event.

In reality, it only took about 15 years for the facility—opened in 1999—to fail.

In a preliminary report issued following the February accident, investigators said that the facility didn't have an adequate radiation safety plan in place, and it had a workplace culture where employees were reluctant to report safety issues or complain about failing equipment or unsafe conditions.

Now, according to the Los Angeles Times, WIPP officials say that it's going to take some 7,000 steps to clean up the mess from February's accident—at a cost estimated by outside experts of at least $1 billion, if not substantially more.

…the Energy Department must drill a new ventilation shaft, repair a broken waste hoist, clean up debris and soot, stabilize the mine walls that have gone unattended for nine months, put new batteries in vehicles, install a new ventilation system, erect a bulkhead to seal off the room with the ruptured drum and seal surfaces that are contamined (sic) with radioactive dust…

Officials say that WIPP will be closed until at least 2016, but nuclear watchdogs say that even that time estimate is probably too optimistic until more is known about how much nuclear waste needs to be cleaned up at the site.

In addition, nuclear waste is backing up at DOE cleanup sites around the nation—adding even more to the eventual overall price tag.

Still, local politicians around Carlsbad continue to support the facility, which employs about 1,200 people and has—at least prior to the accident—an operating budget of around $200 million.

At Thursday's hearing, Republican New Mexico State Rep. Cathryn Brown actually said she felt better knowing that (at least as far as anybody knows) there are only two problem drums at the facility.

"I think it's good news that they have isolated it to only two drums. I would have thought there would have been more," Brown said.

There still very well could be, as the DOE originally identified 678 waste drums matching the signature of the one that ruptured in February, the Current-Argus reports.

According to the DOE, 113 drums are being held at a temporary facility in west Texas, 55 drums are still in the storage panel with the drum that leaked, 453 drums are in the storage panel with the second suspect drum and another 57 still need to be processed at Los Alamos.

That's an awful lot of potentially toxic places for an empty cardboard glove box to hide.

Image via AP