Organic kitty litter was partially to blame for a multimillion-dollar radiation leak at an underground . nuclear waste dump in New Mexico , scientists revealed this week . The US Energy Department report on last year 's accident at the Waste Isolation Pilot Plant near Carlsbad . showed that a drum of waste containing radioisotopes like . plutonium was improperly packaged at the Los Alamos National . Laboratory near Santa Fe before arriving for disposal . The improper mix in the barrel , including the wrong sort of . kitty litter used to absorb liquids , sparked a chemical reaction . causing it to heat up and generate gases that dislodged its lid , . spewing radioactive materials , investigators found . This barrel at the Waste Isolation Pilot Project near Carlsbad , New Mexico , ruptured a year ago , resulting in radioactive contamination that shut down WIPP indefinitely . Culprit : The waste drum contained 'chemically incompatible ' materials , including Swheat Scoop brand of organic kitty litter . Health scare : The accident at WIPP exposed 22 workers to radiation in amounts not expected to threaten their health . The radiation leak that began in the WIPP disposal chamber . half a mile below ground February 14 , 2014 , 'did not result from . a detonation , ' the 277-page report released Thursday concluded . The accident exposed 22 workers to radiation in amounts not . expected to threaten their health , according to Nuclear Waste . Partnership LLC , the contractor that operates the facility . The accident indefinitely suspended key operations at the . site , the Energy Department 's only permanent underground . repository for certain types of radiological waste tied to US nuclear labs and weapons sites . In September , Energy Department officials estimated the cost . of the initial recovery of the dump at $ 240million and said it . might be two years or more before it is fully operational again . ' I can not say how high a priority it is to get WIPP reopened and operating . In general terms , it is critical for everything we do in geologic disposal of nuclear materials , ' Energy Secretary Ernest Moniz said at a Senate Energy and Water Appropriations Subcommittee hearing earlier this week . The report confirms the agency 's preliminary theories about the cause of the costly mishap and also clarified that just one barrel of waste containing 'chemically incompatible ' materials - including Swheat Scoop brand litter , nitrate salts and a neutralizing agent - from Los Alamos was to blame . A worker drives a cart through a tunnel inside the Waste Isolation Pilot Plant No . 2 , 150 feet below the surface near Carlsbad , New Mexico . The improper mix of chemicals sparked a reaction causing it to heat up and generate gases that dislodged its lid , spewing radioactive materials . The drum of waste that caused the leak came from the Los Alamos National Lab ( pictured ) New Mexico slapped the Energy Department with $ 54million in . fines in December for violations 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 .
A single drum of waste caused accident at Waste Isolation Pilot Plant in a year ago . Barrel contained 'chemically incompatible ' materials , including Swheat Scoop brand litter , nitrate salts and a neutralizing agent . Accident exposed 22 workers to radiation in amounts not expected to threaten their health .