New Mexico’s top environmental official is cautiously optimistic the Energy Department will make its self-imposed Dec. 12 restart date for the Waste Isolation Pilot Plant (WIPP).

In a statement emailed Monday to the Weapons Complex Morning Briefing, a week after WIPP prime contractor Nuclear Waste Partnership partially suspended recovery operations in the mine after a worker detected non-nuclear air-contamination in some corridors, New Mexico Environment Secretary Ryan Flynn said “while we believe a WIPP reopening in December 2016 is a realistic goal, our top priority is protecting the health and safety of the men and women who work at the facility and we will only allow operations to resume when we are satisfied that it is safe to do so.”

The safety pause, meanwhile, is expected to last at least several more days.

“The pause remains in effect to allow time to complete some procedure revisions, which will complete within the next couple of days,” a Nuclear Waste Partnership spokesperson wrote in a Monday email. “Briefings to the workforce will take place following the procedure revisions. We expect to come out of the Safety Pause, which only impacts work in the extreme north and south ends of the underground, within the week.”

WIPP has been closed to new shipments of so-called transuranic waste — equipment and material contaminated by radioactive elements — since an underground fire and unrelated radiation release in 2014.