For the second time in a week, heavy blocks of salt rock fell from the ceiling of a restricted underground corridor at the Waste Isolation Pilot Plant, prompting questions about the readiness of the nation’s only deep-mined nuclear waste storage facility to reopen in December.
An employee of the U.S. Department of Energy’s field office in Carlsbad said Wednesday the incidents do not pose a safety threat or represent a violation of regulatory requirements because they happened in areas devoid of waste drums or people.
Meanwhile, WIPP officials scheduled a town hall meeting next week in Carlsbad to discuss maintenance measures and efforts to ensure that other potential collapses don’t threaten workers’ safety.
The storage facility was closed in February 2014, halting nuclear waste shipments from around the country. The shutdown came following a truck fire and resulting smoke that forced workers to crawl out on their hands and knees. Soon after, a waste drum burst, releasing radiation into underground chambers and into the outside air through vents.
Efforts by mine operators to reopen the facility have stalled on several occasions, and some watchdogs said Wednesday that the rock collapses indicate the repository is far from ready to reopen in just two months.
The Department of Energy employee, who cited department policy for not wanting to be identified, said salt rock collapses are occurring more frequently now because necessary maintenance work has been compromised by limited ventilation and the presence of radioactive contamination in parts of the mine since 2014. A similar collapse occurred in May. Prior to that, there had not been an incident since January 2015.
WIPP includes storage areas 2,000 feet below the Earth’s surface that were hollowed out of a salt bed formation and are secured by a mesh cage and metal bolts. Project managers expect salt eventually will enclose thousands of drums of transuranic nuclear waste within the cavern.
Tim Runyon, a spokesman for WIPP, said in a statement that both collapses were attributed to natural “salt creep,” or movement within the underground formation. He also said the incident happened far from where waste will be stored when the mine reopens.
“The fact that WIPP salt naturally and continuously closes in on open spaces is why it was selected for a waste repository,” Runyon said.
On Sept. 27, crews discovered a mound of collapsed salt rocks in an entry chamber for Panel 4, a storage area officials say has been filled to capacity since 2010.
Runyon’s statement said no one had accessed the area in the past six months.
On Tuesday, a second rock fall was found in Panel 3, another restricted area. Photos show that large planks of salt rock crumbled to the mine floor, filling the corridor and ripping open a metal chain-link cage meant to hold the ceiling in place.
A news release explained that no maintenance work had been done on bolt heads that secure the salt roof since access to the area was restricted in November 2014.
Don Hancock with Southwest Research and Information Center called the incidents “entirely predictable” and said he doubts WIPP will be ready to open for many months.
“This is a continuing problem that is likely only going to get worse,” he said.
Hancock said Department of Energy contractors initially expected the rate of salt creep would be an inch a year. But in April, he said, department officials said the salt formation can shift as much as 6 inches per year, making the work of maintaining the mine’s integrity a more rigorous task.
Because of lingering radioactive contamination and a still-compromised ventilation system, Hancock said, “They can’t do everything they need to do, therefore the facility is unsafe and getting more unsafe.”
Meanwhile, radioactive waste has been sitting at national laboratories, with new waste added to the backlog daily as laboratories work to revitalize the nation’s aging nuclear arsenal.
Contact Rebecca Moss at 505-986-3011 or firstname.lastname@example.org.