Yes, The Brand of Kitty Litter Does Matter

Radioactive kitty litter may have ruined our best hope to store nuclear waste

Some of the most dangerous nuclear waste in the US is currently scattered between 77 locations all over the country, awaiting permanent storage. Until February, many experts suggested that the best place to put it was a facility about 40 miles east of Carlsbad, New Mexico, called the Waste Isolation Pilot Plant (WIPP). For 15 years, WIPP has operated as the first and only permanent, deep geologic nuclear waste storage facility in the country, holding "low level" radioactive materials — mostly clothing and tools exposed to radiation from nuclear weapons production — in steel barrels more than 2,150 feet below the Earth’s surface.

But earlier this year two emergencies brought that suggestion — and WIPP’s future — into question. And now it seems kitty litter may be to blame.

WIPP is in a salt desert, and much of the work there involves burrowing through the salt and using huge elevators to deposit the stuff at surface level. The resulting underground caverns are then filled with radioactive waste and eventually closed shut, sealed forever.

...on Valentine’s Day, an alarm sounded, indicating that radioactivity was present in the air underground. No one was below ground at the time, but employees on the surface activated massive fans designed to ventilate the underground air. The next day, another monitor went off — this one on the surface — indicating airborne radiation. Employees who worked outside on the surface were told to take shelter inside buildings completely separated from storage operations. Valves allowing air to flow underground were sealed with high-density expanding foam. Everything came to a standstill, indefinitely.
. . .
Last month, DOE investigators went into the cavern. Pictures showed that the latter hypothesis was true; a waste container’s lid was unsealed, and dust around the lid had turned yellow from the unusual heat emanating from inside. Each barrel is labeled to track where it came from. The punctured barrel originated from Los Alamos National Labs.

Jim Conca, PhD, a geologist who worked for years at WIPP who now blogs at Forbesabout energy issues, believes he knows what blew the lid off at least one of WIPP’s radioactive barrels. The culprit, he wrote, was kitty litter.

As Conca explains it, inorganic cat litter has properties that make it ideal for stabilizing nitrates in radioactive material — for ensuring that it doesn’t dry out and become dangerously hot. So kitty litter is often mixed in barrels with the low-level waste that’s eventually sent to WIPP. What happened at WIPP, he believes, is that one of the radioactive shipments was mixed with organic instead of inorganic material. "‘Green’ cat litter," he writes, is "made with materials like wheat or corn. These organic litters do not have the silicate properties needed to chemically stabilize nitrate the correct way." The result: "solutions can ignite when they dry out."

Mixing organics with nitrates is one of the big no nos of  chemistry, unless you are deliberately trying to make something highly flammable, and possibly explosive. To think that this rooky error has shut down a multimillion dollar waste disposal site essential to national security verges on tragic, with highlights of comedy. But it shouldn't "ruin" our best hope to store nuclear waste.  Nothing can ever be absolutely fool proof, and we'll never run out of fools.