ALBUQUERQUE, N.M. (AP) — The reopening of the nation's only underground nuclear waste repository nearly three years after a radiation leak marks a key step toward cleaning up a decadeslong legacy of bomb-making and research, but the U.S. energy secretary said more needs to be done before a backlog of contaminated material starts heading to the New Mexico desert again.
The radiation release halted work at the Waste Isolation Pilot Plant and derailed a multibillion-dollar cleanup program, raising questions about oversight across the U.S. nuclear weapons complex and leading waste to build up at sites around the country.
Energy Secretary Ernest Moniz told The Associated Press that sweeping changes have been made to improve safety and that hard work by employees and technological advancements over the last three years should bolster public confidence in cleanup efforts following the 2014 leak.
"We are very, very excited about getting at least a resumption of operations," he said during an interview late Sunday. "I do want to caution we will not be at full speed yet for a few years."
Moniz, Gov. Susana Martinez, members of the state's congressional delegation and others gathered Monday to formally mark the reopening of the site in southern New Mexico.
Officials shut down the repository in February 2014 after a chemical reaction inside a drum of inappropriately packed waste caused the lid to burst, contaminating some disposal vaults, corridors and air shafts.
The facility is carved out of an ancient salt formation about a half-mile below the desert surface, with the idea that eventually the shifting salt will entomb the waste.
Moniz acknowledged that the closure caused a backlog of waste at sites including northern New Mexico's Los Alamos National Laboratory, the birthplace of the atomic bomb, and the Savannah River Site in South Carolina, where the basic materials used to fabricate nuclear weapons were produced.
The secretary is hopeful shipments can resume later this year, but work to move the waste underground takes more time now because of the extra clothing, respirators and heavy monitoring devices that workers must wear to protect against the contamination. Limited ventilation also slows the work.
While no schedule has been finalized, officials expect the repository will be accepting about five shipments a week later this year.
The radiation leak also triggered intense state and federal investigations that revealed mismanagement, lax oversight and a failure to follow existing policies.
New Mexico cited the Waste Isolation Pilot Plant and Los Alamos lab — where the drum was packed — for numerous permit violations, while federal investigators detailed a list of corrective actions. Negotiations eventually led to the largest settlement ever between the Energy Department and a state.
"Bottom line: We moved quickly to hold the federal government accountable," Gov. Martinez said in a statement.
She also thanked Moniz and the department for taking responsibility, noting the importance of the repository to the U.S. and the state's economy.
The leak has been costly, with cleanup expected to approach a half-billion dollars once a new, permanent ventilation system is installed. Watchdog groups also have accused the federal government of rushing to reopen the facility.
Following a series of reviews and an inspection by New Mexico regulators, workers last Wednesday moved the first two pallets of waste from an above-ground storage building underground.
Moniz said the department has learned a lot since 2014: the criteria for characterizing, treating and packaging waste has been overhauled and numerous technological advancements have been made as scientists worked to solve problems the agency had not encountered before.
"The workers had some really challenging environments to deal with because of the contamination," he said. "That really made for a tough period, but again ingenuity came to the fore."