The U.S. Department of Energy and the contractor that runs the federal government's troubled nuclear waste repository say it could be more than three years before all operations resume at the Waste Isolation Pilot Plant in southern New Mexico.

The repository has been closed since February 2014, when a canister of waste from Los Alamos National Laboratory leaked in one of its underground storage rooms. Twenty-two workers were contaminated, and the indefinite closure has stalled efforts around the nation to clean up tons of Cold War-era waste.

The Energy Department and Nuclear Waste Partnership detailed the timeline Wednesday for decontaminating parts of the repository and resuming waste disposal.

While limited operations are expected to resume sometime in 2016, officials said a new ventilation system and an exhaust shaft would need to be installed before shipments of waste could be accepted again by the plant. That work could take until 2018 to complete.

Managers have already missed one of the first deadlines in the recovery plan — the New Year's Day target for closure of a storage bunker affected by the radiation leak. It could be April before that happens since more radiological surveys are needed and other safety precautions have to be taken.

Watchdog Don Hancock, who attended Wednesday's meeting in Carlsbad, said officials confirmed that workers would have to wear protective clothing and use breathing equipment while sealing the bunker.

"The initial closure of Panel 6 was supposed to be one of the quick and easy things to be done. It's not done. It's not quick. It's not easy. There are going to be risks to workers just to do that," he said.

"This is in fact unprecedented and very hard and it's taking longer and it's going to cost more than what they've generally wanted to talk about," Hancock said of the overall recovery effort.

Despite delays and added costs, Hancock said WIPP's reopening shouldn't be driven by any particular date. He said alternatives need to be considered and the public and technical experts should be part of that process.

Joe Franco, manager of the DOE's Carlsbad Field Office, said Thursday in a statement that officials are still aiming for limited operations in 2016 but acknowledged that adjustments in the schedule are to be expected given the complexity of the project.

Officials said the main elevator used to take employees below the surface was cleared this week to resume normal operations. Previously, only equipment was allowed on the elevator.

Crews are also using a video camera attached to a special mechanical arm to get a better look at the area where the drum from Los Alamos ruptured. That work is expected to be complete in about two weeks, clearing the way for investigators to finish their final accident report.