Wrong kind of kitty litter blamed for $240m radiation leak at New Mexico nuclear waste dump

"Chemically incompatible" contents caused Drum 68660 to burst open, contaminating 21 people

An improper mix, including the wrong kind of cat litter, in a drum of nuclear waste caused the barrel to burst and release radioactive materials. (Getty Images)

A radiation leak at an underground nuclear waste dump in New Mexico was caused by the wrong kind of cat litter, an investigation has found.

Government scientists concluded on Thursday that last year’s major accident at the Waste Isolation Pilot Plant (WIPP) near Carlsbad was caused by “chemically incompatible” contents, including the wrong kind of kitty litter used to absorb liquids, which reacted inside a barrel of waste causing it to burst open and spew radioactive materials.

The incident on February 14 contaminated 21 people with low-level radioactivity.

The drum of waste, containing radioisotopes like plutonium, was improperly packaged at the Los Alamos National Laboratory near Santa Fe before arriving for disposal, according to a U.S. Energy Department Report.

A summary of the report said workers put the kitty litter brand “Swheat Scoop” in to Drum 68660. The improper mix caused the barrel to heat up and generate gas which caused it to rupture and release radioactive materials.

“Experiments showed that various combinations of nitrate salt, Swheat Scoop®, nitric acid, and oxalate self-heat at temperatures below 100°C. Computer modeling of thermal runaway was consistent with the observed 70-day birth-to-breach of Drum 68660,” the summary said.

The workers were exposed to radiation in amounts not expected to threaten their health, according to Nuclear Waste Partnership LLC, the contractor that operates the plant.

Energy Department officials estimated in September that the cost of the initial recovery of the dump would be $240 million. It may be two years or more before the dump is fully operational.

The report confirms the agency’s preliminary theories about the cause of the costly mishap and also clarified that just one barrel of waste from Los Alamos was to blame.

New Mexico slapped the Energy Department with $54 million in fines in December for violation of state hazardous waste permits tied to WIPP and the Los Alamos lab.

Also last year, a team of federal inspectors released a report that cited chronic lapses in safety procedures at Los Alamos that contributed to the radiation leak.

The lab’s “waste processing and safety-related control procedures should have prevented the addition of these potentially incompatible materials,” the inspectors said of the ruptured waste barrel.

The Energy Department could not be reached immediately for comment late Thursday.

Additional reporting by Reuters