ALBUQUERQUE, N.M. — Dozens of drums of radioactive waste at one of the nation's premier weapons laboratories are stable after some showed signs of chemical reactions over the past year, according to federal officials.
The drums are being closely monitored after a chemical reaction inside a container with similar contents caused a breach in February 2014, resulting in a radiation release and the indefinite closure of the country's only underground nuclear waste dump.
Investigators with the U.S. Energy Department confirmed during a recent town hall that there have been chemical reactions in the containers stored at Los Alamos National Laboratory, but the gases building up inside have decreased over the past several months.
"That would suggest that the reaction, if it is occurring, is slowing down. It's reached a steady state, and it has stopped," said John Marra, chief research officer for Savannah River National Laboratory and one of the investigators who reviewed the cause of the 2014 radiation leak at the Waste Isolation Pilot Plant in southern New Mexico.
Monitoring of the temperature and the gases — which can include hydrogen, carbon dioxide and nitrous oxide — has provided evidence of fluctuation inside the drums remaining at Los Alamos.
"Some of it is just normal oxidation, but some of it may be at a different rate than others. Every drum is unique," said Ted Wyka, head of the Energy Department's Accident Investigation Board.
Wyka added that none of the changes has been at the same level and rate as the drum that popped its lid after being placed into storage at Waste Isolation Pilot Plant.
Still, Marra and others warned during the public meeting in Carlsbad last week that managers at the Los Alamos lab will have to consider the hazards of handling the drums as they craft a plan for permanent disposal.
Any plan would have to be approved by the New Mexico Environment Department, and the cleanup of the Cold War-era waste is a long way off given the indefinite closure of the Waste Isolation Pilot Plant, officials have acknowledged.
The closure has delayed cleanup of legacy waste like contaminated gloves, tools and clothing from decades of bomb-making across the federal government's nuclear complex. In its 15 years of operation, the nuclear dump received shipments from more than 20 different sites as part of the Energy Department's multibillion-dollar-a-year cleanup program.
State environment officials said Monday that Los Alamos lab has been providing biweekly updates and written reports on the status of the drums, which include several dozen containers filled with nitrate salt residues, a neutralizing agent and organic cat litter meant to absorb moisture.
Investigators say the combination of those ingredients and the way they were placed inside the drum spurred the chemical reaction that resulted in the breach at the Waste Isolation Pilot Plant.
As a precaution, the remaining drums at Los Alamos were packed in protective waste boxes last May and placed in domed vaults that are temperature controlled and have filtration systems.
There have been no signs of concern in any of the drums, lab director Charlie McMillian told staff in a memo last week.