The Idaho Department of Environmental Quality is reviewing Fluor Idaho’s plan to restart sludge waste repackaging at the site where four drums of radioactive waste overheated and blew off their lids at the Energy Department’s Idaho National Laboratory a year ago.
The state agency received formal submittal of the corrective action plan April 11, the one-year anniversary of the accident, and hopes to complete its review in the near future, Brian English, DEQ hazardous waste permits manager, said in a Monday email.
Fluor Idaho aims to resume packaging in the next few weeks.
“We want to make sure if we have any more surprises, they are ready for them,” English said by telephone Wednesday. Under its INL regulatory agreement with the Energy Department, the Idaho DEQ has less than 30 days to complete its review.
The four drums spilled radioactive material inside the Accelerated Retrieval Project No. 5 (ARP-5) facility within the lab’s Radioactive Waste Management Complex around 10:30 p.m. on April 11, 2018. In an October analysis, Fluor Idaho said the temperature inside the 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 55-gallon drums involved in the accident contained sludge waste generated decades ago at the old Rocky Flats nuclear weapons plant near Denver. The waste, buried on-site at the Idaho National Laboratory for years, was being repackaged inside the ARP fabric filter building.
This involves removing the contents from the old drums and placing them on tables or trays, then removing any potential sources of ignition before placing the material into new drums. The empty drums are later crushed and incorporated into the waste stream.
Usually if there is going to be oxidation, the “sparking” occurs quickly on the table or after the material is placed into the new drum, English said.
This April 2018 situation was different in that the oxidation happened several hours later. Officials have suggested poor record-keeping from Rocky Flats meant workers at Idaho lacked sufficient chemical data on potential sources of ignition inside the old drums.
The four problem drums that overheated all contained material from one old parent drum from Rocky Flats, English said.
In its filing with the state, Fluor Idaho said it plans more extensive thermal monitoring to spot temperature increases in sludge waste sooner. The automated thermal monitoring, which previously occurred for a few hours, will now extend to 24 hours after a container of waste is repackaged.
In addition, there will be more raking or slow stirring with equipment when the material from the old drums is placed on the sorting tables. The sorting tables will also be thoroughly cleaned before the contents of each old drum is disbursed.
There were about 41 old drums in the room at the time of the accident, English said. Fluor Idaho expects to complete the job by the end of June, he added.
Fluor Idaho did not comment by press time.
