Officials at the Waste Isolation Pilot Plant nuclear waste repository near Carlsbad said they are making progress on improvements to the facility’s airflow systems to support continued operations.
At WIPP, transuranic (TRU) nuclear waste is disposed of via burial in an underground salt deposit in a network of mined rooms and panels.
To be able to continue emplacing the waste, mining new space and maintaining the underground repository, managers of the facility hope to increase airflows through two ongoing projects: a new air intake shaft and a series of air filtration devices known as the Safety Significant Confinement Ventilation System (SSCVS).
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In total, the two projects are expected to cost about half a billion dollars, and be complete in 2026, increasing air available in the underground from 170,000 cubic feet per minute (cfm) up to 540,000 cfm.
Airflow was restricted in the underground since an accidental radiological release in 2014 contaminated parts of the facility, even after a three-year halt of WIPP’s primary operations in the repository.
The Department of Energy on Tuesday announced subcontractors Shaft Sinkers of South Africa and Colorado-based Harrison-Western reached a depth of 1,818 feet in sinking the new shaft, of a goal of 2,275 feet.
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It will be the site’s fifth air shaft and its largest at 26 inches in diameter.
To continue sinking the shaft, crews used explosives emplaced in boreholes in its walls.
The resulting rubble is removed by remote-controlled mechanical arms on the bottom of a work platform known as the Galloway, which is lowered into the shaft.
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Debris is dumped into buckets and lifted to the surface through the Galloway, dumped into chutes and into a front-loader that carries the rock into a truck which then hauls it away from the site.
Subcontractor for the SSCVS the Industrial Company reported 38 of 44 concrete walls were poured for the plenum of the New Filter Building, where air is held before being pushed through high-efficiency particulate air (HEPA) filters using 1,000-horsepower fans.
The building will use six fans with four operating simultaneously, one kept in reserve and another rotated in and out of service for continual maintenance.
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Four of the fan assemblies were delivered to the site, and are currently in storage.
Workers also poured 13 elevated concrete decks at the filter building, along with all of the 117 walls and interior columns.
All six of the filter units at the SSCVS’ Salt Reduction Building were installed.
That building will “prefilter” the air before it goes to the filter building, misting the air to cause salt to fall to the ground, collecting the resulting brine water and sending it to a collection pond.
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After the air passes through the HEPA filters in the New Filter Building, it is exhausted out of the system in a 125-foot-tall exhaust stack.
Sean Dunagan, president of Nuclear Waste Partnership (NWP), WIPP’s primary operations contactor said he expected the ventilation upgrades at the site to improve WIPP operations as it continues to operate.
“It’s exciting to see the process get underway,” Dunagan said. “The crews are making great progress and doing it safely and compliantly.”
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Concerns with underground airflow were expressed in a monthly report from government watchdog agency the Defense Nuclear Facilities Safety Board.
In its latest report on WIPP, dated July 8, the board reported NWP found a potential airflow configuration for the soon-to-open eighth disposal panel, could inhibit the ability of air monitors to detect a radiological release in Panel 7 – the area where the 2014 release occurred.
After additional analysis, NWP reported the concerns were allayed as they pertained to an airflow configuration that would not be used.
This scenario would involve a bulkhead being removed, the doors to Panel 8 open, and the man-door to another bulkhead being propped open while the mine’s airflow was run in unfiltered ventilation mode.
“This reverse air-flow would inhibit the ability of the continuous air monitors to detect a potential radiological release in Panel 7,” read the report. “NWP performed an additional analysis and showed that this initial concern does not create a reverse air flow.”
The Defense Nuclear Facilities Safety Board said it continued to evaluated NWP’s conclusion on the airflow configuration.
Adrian Hedden can be reached at 575-628-5516, [email protected] or @AdrianHedden on Twitter.