By Laura Zuckerman
(Reuters) - A second container of plutonium-contaminated debris may have contributed to a radiation leak that has led to the indefinite suspension of operations at an underground nuclear waste dump in New Mexico, a U.S. Energy Department official said on Thursday.
Preliminary findings from an investigation of a Feb. 14 accident at the Waste Isolation Pilot Plant near Carlsbad that sent high levels of radiation into a salt mine half a mile (0.8 km) below ground where nuclear waste is stored suggested the culprit was a single ruptured barrel that originated from Los Alamos National Laboratory near Santa Fe.
"What has come out insinuates we have another potential drum," Joe Franco, manager of the Energy Department field office in Carlsbad that oversees the plant, told a public meeting.
Franco said further investigation of the underground suggests the rupture of an additional barrel of nuclear waste deposited in a separate waste panel.
Early investigation findings indicate at least one barrel of waste whose contents included nitrate salts, organic matter and lead underwent a chemical reaction generating heat and ruptured the container.
Don Hancock, head of the watchdog group Southwest Research and Information Center, told Reuters after the public meeting on Thursday that key questions remain unanswered.
"They still don't know the cause. They still don't know if there's more than one breached drum. They still don't have a recovery plan available to the public," he said.
The accident, which contaminated 22 workers with small amounts of radiation not expected to harm their health, was the worst mishap on record at the facility since it opened in 1999.
Government scientists have not been able to replicate the chemical reaction suspected in the radiological release and the Energy Department declined to say if that would be necessary before the plant could reopen to accept waste from U.S. nuclear labs and weapons sites.
It may be years before the dump in the Chihuahuan Desert of southeastern New Mexico is fully operational but recovery of the plant is a top priority, Energy Department officials have said.
(Reporting by Laura Zuckerman in Salmon, Idaho; Editing by Eric M. Johnson, Lisa Shumaker, Robert Birsel)