Officials at the Waste Isolation Pilot Plant are preparing to dispose of nuclear waste in a newly-mined panel in the underground repository, altering air quality requirements due to the new area’s differing dimensions.
At WIPP, transuranic (TRU) nuclear waste is emplaced in panels mined about 2,000 feet underground in an underground salt formation. So far, drums of TRU waste were disposed of in seven panels with mining recently completed in the eighth and final panel.
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The previous seven panels were 13 feet high, but Panel 8 was mined to a height of 16 feet to address concerns about the stability of the panel’s ceiling.
This means allowable concentrations of volatile organic compounds (VOCs) allowed in the air in Panel 8 will be lower due to increased volume, and the U.S. Department of Energy submitted a request to modify its operations permit at the facility to account for the change.
Mining of Panel 8 was underway but not completed when a mispackaged drum of waste ruptured in the underground, leading to a three-year interruption of mining and waste emplacement until 2017.
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Work to mine Panel 8 didn’t resume until a year after that, when it was determined the eighth panel would need to be taller.
It’s the only dimension being altered, as Panel 8 will be 300 feet long and 33 feet wide like the others.
“When we resumed mining, there were some concerns about the stability of the ceiling,” said WIPP spokesman Bobby St. John. “To ensure the long-term stability of the panel, the decision was made to change the height to a new mining horizon.”
The Permit Modification Request (PMR) was submitted Oct. 15 to the New Mexico Environment Department (NMED), and WIPP officials held a required public meeting Tuesday via Zoom.
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Public comments could be submitted to the NMED until Dec. 20 to Ricardo Maestas at NMED either via mail to 2905 Rodeo Park Dr. E, Building 1, Santa Fe, N.M. 87505 or via email to [email protected].
During the meeting, Josh Vajda, an engineer with Regulatory Environmental Services (RES) – a division of WIPP contractor Amentum that oversees permitting at the facility – said the change would not affect WIPP’s VOC monitoring program but was needed to maintain worker safety while in Panel 8.
“The PMR proposed to revise permit restrictive test, applicable figures and applicable tables associated with the room-based limits of VOCs for Panel 8,” he said. “This modification does not reduce the ability of the permitee to protect public health and environment.”
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But the three additional feet of height impacted the allowable volume of nine of 10 VOCs monitored in the underground, reducing their concentrations by about a third.
Chlorobenzene, flammable VOC, maintained its concentration due to its “flammability” limit, Vajda said, while the others were reduced based on the hazard they posed directly to human health.
“The concentrations that are based on the health based limit are decreasing because they are volume dependent,” he said. “Therefore, if we have a taller headspace to ensure we have the proper worker protection they will decrease.”
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St. John said the change in VOC volume was intended to maintain the safety of workers emplacing waste and performing maintenance activities in Panel 8.
“The safety of our workforce is always our No. 1 priority,” he said. “That’s why we’re doing this.”
Bob Kerman, another engineer with RES said the DOE was not required to notify NMED when re-mining Panel 8 but needed the modification to update language in the WIPP permit.
“No notification was required. The permitees were already authorized to mine Panel 8,” he said. “It was authorized in the last (permit) renewal.”
Panel 8 was recently completed and was expected to receive a shipment of TRU waste in April 22, when Panel 7 was predicted to be full, per WIPP officials.
The panel and its seven rooms were still awaiting electrical components like mine phones and air monitors.
“We are all focused on working safely and productively in order to see Panel 8 in use next year,” said Reinhard Knerr manager at the DOE’s Carlsbad Field Office. “It’s been a long time coming, but Panel 8 will be ready just when we need it. My congratulations to all who made this moment occur.”
Adrian Hedden can be reached at 575-618-7631, [email protected] or @AdrianHedden on Twitter.