CARLSBAD – Officials are hoping to seal off the south end of the Waste Isolation Pilot Plant’s underground salt mine, where radiation was accidentally released in 2014, to allay safety concerns and ensure workers have clean air and stable ground in the future.
“Lack of ground control during WIPP’s recovery from incidents in 2014 led to concerns regarding mine stability in this area, reinforced by several rock falls over several years,” said WIPP spokesman Donavan Mager. “DOE made a decision in late 2016 to close the south end to reduce potential worker risks.”
For better efficiency in sealing off the area, which includes six filled waste disposal panels and supporting access areas, the Department of Energy, which owns WIPP, and Nuclear Waste Partnership, which oversees the facility’s operations, proposed a permit modification through the New Mexico Environment Department to redefine how panels are permanently closed.
A public notice on the proposed modification was issued late last month by NMED, opening a 60-day public comment period until April 23.
The DOE and NWP first submitted a revised modification request to NMED on Nov. 10, 2016, records show, which included adjustments to WIPP’s Panel Closure Plan.
“This permit modification will allow DOE to deliberately and safely withdraw and seal the south end of WIPP,” Mager said. “The change greatly simplifies the process of closing these areas, isolating them from personnel access and eliminating the need for ongoing maintenance, ventilation and ground control.
“The goal is to redefine what has to be done in order to permanently close filled waste disposal areas.”
Originally, WIPP’s permit to seal the panels required the use of 12-foot-thick concrete walls to block off each panel, with a larger structure to prevent any additional airflow or ground movement.
Mager said recent testing indicated the walls were not needed for future closures, and that mined salt could be reused in the disposal process.
The decision to propose altering the process arose from testing at WIPP as to the accumulation of hydrogen and methane gases in a filled disposal panel. The rate of accumulation inside the filled panel was much lower than expected, Mager said, leaving the concrete structures unneeded.
Instead, metal bulkheads could be erected to close off the panels in place of the walls, and the panels could be backfilled with reused salt.
“Erecting bulkheads is inherently simpler and safer than the original concrete and cement block concepts,” Mager said.
Closure of the area where the radiation was released is essential for ongoing safety during WIPP operations, he said.
Blocking off the area will also increase airflow in the underground, allowing more workers in at a time.
“Closing filled areas allows the DOE and NWP to isolate them from personnel access, an important worker safety measure,” he said. “Finally, it will allow the DOE and NWP to meet requirements in their permit with the NMED to permanently close filled waste panels so the waste is isolated.”
The presence of radiation in the air in the panels to be sealed, Mager said, made it “extremely difficult” to achieve the previous design.
He said the proposed changes will allow workers to completely seal off the waste, while ensuring the safety of personnel.
Don Hancock, director of the Nuclear Waste Program at the Albuquerque-based Southwest Research and Information Center, said he agrees with sealing off the south portion of WIPP, even getting rid of larger secondary structures, but contended that bulkheads already proved they could fail during the 2014 incident.
The backfilled sand, he said, could leave a gap at the top of a room where airflow could further contaminate the site and provide fuel for an explosion.
The center will file comments during the public comment period, Hancock said, and request a hearing with the DOE.