HOUSTON, May 16 (Xinhua) -- Officials have pinpointed the source of a radiation leak at an underground nuclear waste repository in the U.S. state of New Mexico to a container shipped from a national laboratory manufacturing nuclear weapons, U.S. media reported Friday.
The U.S. Department of Energy said in a statement released on Friday that pictures from the latest entry into the Waste Isolation Pilot Plant (WIPP) near Carlsbad in southeastern New Mexico confirm that a container from Los Alamos National Laboratory has a cracked lid and evidence of heat damage, local media KOB reported.
It was not the first time that the department linked the radiation release to the waste containers from Los Alamos. Earlier officials said they believed a chemical reaction happened inside the waste drums which were shipped from the laboratory and stored at the underground vault in WIPP.
Investigators suspect a change of "kitty litter" used to absorb liquid in the waste may have led to the chemical reaction. But there is no final word as crews were investigating the cause of the leak, which has shuttered the dump for more than two months and exposed 21 workers.
The Los Alamos laboratory, also located in New Mexico, has halted its shipment of the waste containers in question to a storage site in Texas, a temporary place the lab used to discard its waste after the WIPP was shut down.
The nuclear weapons manufacturer said Friday that it "is fully cooperating" with state and federal officials and has taken extra precautions to ensure that similar waste drums at the lab and those sent to Texas "are in a safe and controlled configuration."
The nuclear leak happened on Feb. 14 when sensors detected unusually high levels of radioactive particles in the underground dump. It has been kept shuttered since then. Officials said last week that it could be up to three years before full operations resume at the underground facility.
The WIPP stores "transuranic waste" leftover from nuclear weapons research and testing from the nation's past defense activities, according to the Energy Department's website. The waste includes clothing, tools, rags and other debris contaminated with radioactive elements, largely plutonium.