Metal nitrate salts plus wheat equals a half-billion dollars

Also in this week's C&EN,  Jessica Morrison interviews Savannah River National Laboratories chemist David Hobbs, who has been one of the researchers of the 2014 Waste Isolation Pilot Plant runaway reaction problem. I have known a little bit of the story, but it is rather devastating to read it all in one place:

...Hobbs, who doesn’t own a cat, is one of the researchers who studied the nuclear waste mixture that in 2014 led to a drum failure and radiological release at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, N.M. The accident shut down the facility for three years... 

...But an April 2014 accident investigation report by the Department of Energy came to a different conclusion. It says the radiological release likely stemmed from a single breached drum. Plus, photographs taken in May 2014 show an open container with heat damage to the surrounding area. This suggests that a thermal event inside the drum caused the container to fail. 

The drum came from Los Alamos National Laboratory (LANL). It contained a reactive mix of radioactive nitrate salt waste, a neutralizing liquid, and organic cat litter, which had been used as a sorbent. 

An October 2014 report from the Department of Energy’s Office of Inspector General points to a change in the packaging procedure at LANL that specified organic cat litter, when an inorganic sorbent was likely intended. Investigators traced a series of internal communications in which the specifications for “kitty litter/zeolite clay” were transformed into “kitty litter (clay),” the report says. 

Combined with inadequate technical review, this resulted in LANL workers filling waste containers with a mixture of nitrate salts and sWheat Scoop, a cat litter that is 100% wheat, according to its manufacturer. 

“It would have been much clearer if they had said an inorganic zeolite sorbent,” Hobbs says. “It’s been a very expensive mistake, costing at least half a billion dollars.” (emphasis mine) 

...Inside the drum was “a complex, heterogeneous mixture of materials with the potential for multiple reaction sites and reaction chemistries,” Hobbs and his team said in a March 2015 DOE report. 

The contents of the drum, which included metal nitrate salts, the sWheat Scoop litter, and a neutralization reagent, were incompatible, the report says. The mixture likely underwent a series of exothermic reactions, including hydrolysis, oxidation, and nitration of the organic components, the report says. The reactions produced a thermal runaway condition in which increasing internal heat and pressure caused the waste container to break open and release radioactive material. 

Hobbs says questions remain about why only one drum failed. LANL generated nearly 700 drums with a similar waste mixture that includes the organic cat litter. Drums with similar mixtures were isolated and are monitored, DOE says....

As a chemist who works in manufacturing, who works on larger scales and writes specifications, I can only hope beyond hope that I will never be responsible for such a massive, costly failure. Good heavens.