The Department of Energy is requiring over a dozen of its cleanup sites to conduct extensive evaluations of their radioactive waste holdings and safety practices, in hopes of preventing a repeat of the April 2018 sludge release at the Idaho National Laboratory.
The facilities overseen by DOE’s Office of Environmental Management (EM) have until Sept. 30 to finish their site-specific extent of condition reviews.
The reports will be used to produce a full complex review focused on “radioactive or mixed waste streams and waste drums with uncertain or unknown components that could pose pyropheric or reactive conditions similar to those encountered at Idaho,” the Environmental Management office said in a safety alert distributed to site managers on May 28. “These are expected to be primarily legacy waste streams, given that newly generated waste streams typically have more complete process documentation and characterization before packaging.”
Copies of the safety alert were provided Thursday to attendees of a Defense Nuclear Facilities Safety Board hearing in Washington, D.C., on safety in Energy Department storage and processing of radioactive waste. Four senior officials from the Office of Environmental Management and DOE’s semiautonomous National Nuclear Security Administration testified regarding lessons learned and operational improvements following the Idaho incident and a February 2014 radiation release at the Waste Isolation Pilot Plant (WIPP) in New Mexico.
The Environmental Management office on Friday did not discuss a schedule for the complex-wide review. “The need and timeline for any additional actions or guidance to sites will be determined based on the outcomes of the review,” it said in a statement to Weapons Complex Monitor.
The Idaho National Laboratory and other DOE facilities around the nation are charged with treatment, packaging, and shipment of radioactive waste from decades of nuclear weapons operations, some of it dating to the Cold War. Much of it is transuranic waste like that involved in the Idaho incident – material with more than 100 nanocuries of alpha-emitting transuranic isotopes per gram of waste with half-lives exceeding two decades – that is ultimately sent to WIPP for permanent disposal.
On April 11, 2018, four drums of sludge waste overheated and blew off their lids hours after the contents were exposed to air during repackaging at the Idaho lab’s Accelerated Retrieval Project 5 (ARP 5) facility. The waste, stored for decades on-site in Idaho, originally came from the Rocky Flats nuclear weapons plant in Colorado. Some of the sludge was released from the drums into the surrounding area.
Lab cleanup contractor Fluor Idaho conducted the incident investigation, which identified two specific mechanisms for the accident, according to the safety alert: oxidation of pyropheric non-roaster-oxide depleted uranium metal powder and fine material over eight hours; and production of “substantial amounts of methane through beryllium carbide hydrolysis.”
The actual event derived from two longer-term root causes: inadequate controls for treatment of waste that did not arrive with documents clearly showing its origin or process data, along with failure by leaders over a period of years to develop the site safety culture. Contributing causes included the absence of a documented disposal plan and failure to apply lessons learned from a pyropheric incident at another Idaho National Lab facility in December 2017.
After remediation of the impacted site was completed, Fluor Idaho resumed sludge repackaging this spring in ARP 5.
The safety alert, with the requirement for the site condition of review, was sent to the managers of DOE nuclear cleanup offices at Idaho, the Los Alamos National Laboratory in New Mexico, the Oak Ridge Reservation in Tennessee, the Hanford Site in Washington state, the Paducah Site in Kentucky, the Portsmouth Site in Ohio, the Savannah River Site in South Carolina, the Energy Technology Engineering Center in California, the Moab UMTRA Project in Utah, the Nevada National Security Site, and the Separations Process Research Unit and West Valley Demonstration Project in New York state.
The sites’ reviews must include, among other information: a description of the schedule and frequency in which waste drums are tested for concentrations of flammable gas; controls establish to avert or blunt “deflagration hazards”; a full accounting of waste drums in storage that are known to or believed to hold metal carbides; and identification of the source and inventory of waste drums in storage in which available data is not sufficient to determine the danger of flammability or other reactions.
The safety alert also provides seven recommendations for cleanup site managers, including incorporating lessons learned from the Idaho incident into their own operations, ensuring effective controls in management of waste with “uncertain pedigree,” and reviewing procedures for repackaged waste.
In addition, the Office of Environmental Management is revising its 12-year-old Standard 5506 document, on preparation of safety basis documents for facilities that hold transuranic waste, officials said Thursday.
The waste generator sites and WIPP all have specific safety bases for determining their potential hazards and identify measures to prevent or mitigate accidents, DNFSB Technical Director Chris Roscetti noted to the three board members. Energy Department contractors use Standard 5506 in determining which event scenarios to analyze and how they should be evaluated, he said.
The DOE revision dates to 2015, board member Joyce Connery said. The DNFSB last year issued a technical report laying out deficiencies with the standard as it exists now, she added. For one, according to the board, the Energy Department has yet to revise the document to address the potential for chemical events to produce larger than anticipated radiation releases.
The current document over more than a decade has met its objectives in creating a set standard for analyzing potential dangers associated with transuranic waste treatment and storage, said Dae Chung, EM deputy assistant secretary for safety, security, and quality assurance. He added that it is just one aspect of a broader set of safety measures for waste sites.
“We do have a suite of directives and resulting controls that we apply during our day-to-day operations,” he told the board.
Completion of the updated Standard 5506 was delayed to ensure DOE fully understood the Idaho incident and conducted some testing, Chung said. The office on Thursday issued its project review justification and expects to publish the revision in 2020.
