A Scientist Bought the Wrong Brand of Kitty Litter, Caused a Nuclear Accident

​On Valentine's Day of last year, workers at the only permanent underground nuclear waste storage facility in the United States had to be evacuated after an explosion caused radiation to leak into New Mexico's Waste Isolation Pilot Plant. And it was all caused because a nuclear security employee bought the wrong brand of kitty litter.

Kitty litter is used as a stabilizing agent in nuclear storage—silicates in cat litter stabilize radioactive nitrate salts. If the salts aren't stabilized before they dry out, they can eventually overheat and release dangerous gases. (In this case, it seems the barrel in question sat for months before causing problems.)

A report released Thursday by the Department of Energy suggests that an organic brand of cat litter, Swheat Scoop, was used to pack a drum of nuclear waste stored at the facility. But organic cat litter doesn't contain silicates found in normal cat litter, meaning it didn't have the same stabilizing effect. After a few months, the nitrate salts within the barrel heated up, began giving off dangerous hot gases, and eventually pierced the drum, causing the emergency, in which 21 workers were exposed to radiation.

The DoE says that the levels of radiation the workers and the environment received are not dangerous, long-term.

"The combination of the nitrate salt residues, organic sorbent (Swheat Scoop®), and neutralizing agent (TEA) represents a potentially reactive chemical mixture of fuels and oxidizers," the DoE report reads.

The report is the result of roughly a year's worth of investigation into the incident, but the outcome wasn't unexpected: The DoE already suspected that organic kitty litter may have had something to do with the explosion, but lab tests and recreations were done to confirm what government researchers had already proposed. The incident has created the odd situation in which a kitty litter manufacturer's name is mentioned 400 times in a 277-page report.

Storing nuclear waste is tricky business—it lasts at least 24,000 years, so we don't want it seeping into the ground, and incidents like this always call into question the sustainability of any permanent storage facilities.

In a sense, user error is good news for the future of the plant. James Conca, a former employee of the plant, wrote in an editorial at Forbes that if kitty litter was indeed responsible for the explosion, it's a bad mistake, yes, but it doesn't say anything about the overall safety of the facility.

"WIPP and the salt host rock had nothing to do with the drum that burst," Conca wrote. "So, as far WIPP itself goes—no health concern, no environmental concern, no safety concern, and now no operational concern. The performance basis of WIPP is still excellent."