Repackaging of radioactive sludge waste at the site of an April 2018 drum breach at the Department of Energy’s Idaho National Laboratory is nearly complete, according to a monthly report filed with the Idaho Department of Environmental Quality.
Site cleanup contractor Fluor Idaho said in its June 27 update it has completed processing all material except three waste trays inside the Accelerated Retrieval Project No. 5 (ARP-5) facility within the lab’s Radioactive Waste Management Complex.
The contractor paused processing the remaining waste while the Energy Department conducted additional tests to ensure material in the trays is not too hot. The company expects to finish the remaining waste processing this month, the update says.
In addition, Fluor Idaho plans to file a hazardous waste permit modification with DEQ this month seeking permission to start repackaging material within a different room at the Waste Management Complex.
Waste from around 40 drums remained to be repackaged into new drums in ARP-5 Room 106 at the time of the accident, in which four drums overheated and blew off their lids, spewing sludge onto nearby walls and ceiling. At the end of the day of the 2018 accident Fluor had 27 trays in process with one drum per tray; and 37 drums awaiting processing, according to the Idaho DEQ.
During the processing, waste from old drums is placed onto trays and checked for material that might ignite before being repackaged into new drums that will ultimately be sent for to a disposal site such as the Waste Isolation Pilot Plant in New Mexico.
Fluor Idaho says the temperature inside the four ruptured drums increased to about 150 degrees Celsius after depleted uranium contacted air for the first time in years. Also, material from the drums generated methane, a flammable gas.
The sludge waste inside the 55-gallon drums involved in the accident was first generated decades ago at the Rocky Flats nuclear weapons plant in Colorado. The waste, buried on-site at the Idaho National Laboratory for years, was being repackaged inside the ARP fabric filter building.
The accident was unusual in that the overheating occurred hours after the waste was removed from the old drums and contacted the air. Typically, any overheating would happen within a few minutes, according to reports filed with the state and DOE about the accident.
Fluor Idaho and the Energy Department have implemented additional thermal testing since the 2018 drum breach. This includes more extensive checks for overheating or sparking on the tray tables, along with longer observation of the repackaged drums.
Defense Nuclear Facilities Safety Board Chairman Bruce Hamilton says spotty record-keeping from Rocky Flats did not give a full picture on what potential flammable material might have been inside the old drums.
Fluor Idaho holds the $1.5 billion Idaho Cleanup Project contract, which runs through May 2021. One of its chief tasks includes treating and shipping transuranic waste to WIPP. Since 2012, the Idaho Cleanup Project has processed and repackaged about 9,500 drums of sludge-contaminated waste that originated at the former Rocky Flats, Fluor Idaho said.
