After a suspension of several months, Fluor Idaho is again excavating a tranche of Cold War waste at the Energy Department’s Idaho National Laboratory.
The Idaho Cleanup Project contractor voluntarily suspended the work in the lab’s Accelerated Retrieval Project 8 space following an April 11 breach of four drums at the Accelerated Retrieval Project 5 site. ARP 5 is at the east end of the lab’s Subsurface Disposal Area (SDA) and ARP 8 is at the west end, according to Idaho officials.
Following a safety review of the waste exhumation, Fluor Idaho implemented more safety controls, which include thermal monitoring and raking the old sludge waste before repackaging.
The extra wait time after additional raking ‘allows potentially slower reactions to be detected,” Daryl Koch, a manager with the hazardous waste unit of the Idaho Department of Environmental Quality, said in a Thursday email.
Raking is a process performed with the bucket on the excavator by the operator in the cab wearing anti-contamination clothing and supplied air. It’s already done at a couple of locations at the ARP after the waste containers have been opened. It’s always been done on substances which might spark or material containing depleted uranium. “What is new to the process is an additional 24 hour “wait” time after raking to see if a slower reacting exothermic reaction will take place,” Koch added.
Corporate and regulatory officials in Idaho are evidently searching for chemical or radiological traits in the material, which could cause a release of heat similar to the one that resulted in the drum breach episode in April.
While ARP 8 is exhuming buried waste and ARP 5 is repackaging stored waste from the Advanced Mixed Waste Treatment Project at INL, both waste streams originated at the former Rocky Flats nuclear weapons plant in Colorado, Koch said.
The material being unearthed was shipped to the lab from the 1950s through 1970, according to Fluor Idaho. Years ago, the Idaho National Laboratory was the designated disposal location for Atomic Energy Commission wastes from Rocky Flats.
Idaho, the Energy Department, and the U.S. Environmental Protection Agency reached agreement in 2008 for DOE to clean up about 6 acres of buried sludge material including uranium, plutonium, and solidified solvents. After being repackaged at Idaho, the material is ultimately shipped as transuranic waste to DOE’s Waste Isolation Pilot Plant in New Mexico.
In recent years workers have removed buried waste containing plutonium, solidified solvents, and uranium, also called “roaster oxides,” from a combined area of 1.54 acres of ARP 8, which is about 90 percent complete, according to Fluor Idaho. Altogether there are nine retrieval enclosures within the Accelerated Retrieval Project. The ARP is part of the 97-acre SDA landfill within the Radioactive Waste Management Complex.
Fluor Idaho has yet to determine the cause of the April 11 incident, in which the 55-gallon drums of radioactive sludge overheated and ejected their lids, causing waste to spill onto the floor and walls of the room in which they were located. The contractor has told state officials it expects to issue its investigative report in November.
The accident happened at Airlock 5 of the Accelerated Retrieval Project 5 facility, where exhumed waste drums are opened, treated to remove banned items, and repackaged. The four breached drums had not yet been certified for transport to WIPP.
Fluor Idaho has a five-year, $1.4 billion contract for cleanup operations at the lab.
