Workers initially detected no free-floating contaminants as they re-entered a New Mexico atomic site evacuated in February, the Associated Press reports.
A pair of eight-person teams on Wednesday descended into the subterranean section of the Waste Isolation Pilot Plant and set up a central operating site in its storage area, the U.S. Energy Department said. The move involved deploying technology to facilitate communications, as well as additional sensor systems in the waste area more than 2,600 feet below ground, the agency indicated in a statement.
The entry by the personnel, who wore air masks and other protective equipment, marked the first human foray into underground corridors of the salt mine since February. Workers stopped entering the area after warning systems identified leaking radioactive particles; since the Feb. 14 incident, signs of radiation exposure have turned up in no fewer than 21 employees.
The escaped contaminants triggered the facility's detection equipment 10 days after a vehicle fire in the underground area. Contaminants have reached the surface only in trace quantities, but the extent of contamination inside the site remained unclear, according to recent reporting.
"Today's efforts were a critical first step toward future entries that will expand the clean base of operations and allow workers to travel farther into the mine to identify the suspected source of the radiological release," the Energy Department press release states.