The Energy Department has temporarily halted salt mining at the Waste Isolation Pilot Plant (WIPP) disposal site near Carlsbad, N.M. Mining has gone slower than expected since it resumed in January, DOE also recently told the Defense Nuclear Facilities Safety Board (DNFSB).
Mining is paused in the newest planned disposal area, Panel 8, until September so DOE and WIPP management contractor Nuclear Waste Partnership (NWP) can shift resources to address ground control issues in other areas of the underground transuranic waste site, according to the latest site report from the DNFSB.
Ground control is a mining term to refer to upkeep of underground shafts, by roof bolting and other means, to preserve evacuation routes and protect workers from being hurt or killed by falling rock.
“Unstable ground conditions are the biggest hazard to workers in the WIPP underground,” according to an Aug. 15 DOE presentation to the independent nuclear safety watchdog. The facility didn’t record any unplanned roof falls prior to 2014, but there have been four since then.
Two February 2014 accidents, a fire and underground radiological release, prevented WIPP from receiving waste for about three years. The accidents also limited access for months to areas of the underground mine where roof bolting was needed. This caused workers to fall behind on that work, although WIPP has now caught up.
In summer 2016, Energy Department officials decided to abandon operations in the far south end of the underground mine due to roof falls.
There are five roof bolting units at WIPP. Three are diesel powered and the two others are hybrids that can run on electricity or diesel fuel. Bolts must be constantly replaced — about 40 of them fail weekly at WIPP, DOE said in its presentation.
The Energy Department is spending $8 million to $9 million to mine Panel 8 and prepare it for waste emplacement in 2021. The agency had hoped to mine 50,000 tons of salt in fiscal 2018, but the facility is on pace to extract only between 35,000 and 40,000 tons.
There are various reasons. For one, only one mining machine is currently operating at WIPP, so progress halts with any maintenance or unexpected repair, DOE told the DNFSB. It is possible a second machine could be recovered from another area of the mine. The purchase of a used or refurbished machine from a local potash mine is also possible.
There is also now only enough airflow underground to accommodate two haul trucks, which are used to carry away the muck from salt mining. Panel 8 will need about 113,000 tons of rock salt to be mined and moved out prior to waste emplacement, DOE said.
WIPP Panel 7 is expected to be filled in March 2021. Panel 8 could start receiving waste containers in January 2021, Carlsbad Field Office Manager Todd Shrader said recently.
A contract for construction of a new permanent WIPP ventilation system could be announced in September. Current ventilation underground is about 114,000 cubic feet per minute. The new ventilation system, due to come online in 2021, should boost airflow to more than 500,000 cubic feet per minute.
The House Appropriations Committee has told WIPP to report to Congress within 60 days of final passage of the fiscal 2019 budget on underground maintenance issues at the underground mine, including roof bolting and development of new panels.
