Transuranic waste containers at LANL are loaded for transportation to WIPP. Photo Courtesy LANL
BY MAIRE O’NEILL
The Defense Nuclear Facilities Safety Board told Energy Sec. Dan Brouillette in a Sept. 24 letter that DNFSB has reviewed transuranic waste storage, handling and processing across Los Alamos National Laboratory facilities and found that safety bases for both National Nuclear Security Administration and Environmental Management facilities at LANL do not consistently or appropriately consider a potential energetic chemical reaction involving transuranic waste.
The Board alleges that LANL hazard analyses lack systematic evaluations of the chemical compatibility of transuranic waste streams.
“These analyses are needed to fully identify potential chemical reaction hazards associated with waste constituents,” the letter, signed by Acting Board Chair Thomas A. Summers, states.
The Board says accident analyses are not bounding, assume inappropriate initial conditions and “do not defensibly estimate the quantity of radioactive material that may be released due to an energetic chemical reaction”
“As such, additional credited safety controls may be necessary to protect workers and the public,” the letter states.
Some facilities store transuranic waste without any engineered controls beyond the waste container, the Board notes.
“The radiological release events that occurred at the Waste Isolation Pilot Plant and Idaho National Laboratory have demonstrated the importance of incorporating multiple layers of protection to reduce the consequences of an accident,” the letter says.
The Board asked DOE provide a report within 120 days that describes whether the hazards associated with the current waste contained population at LANL are consistently and adequately controlled and DOE’s basis for this position, and whether or not a revision to DOE Standard 5506 will address the broader implications of the Board’s concerns as they are applicable to other DOE sites.
DNFSB staff evaluated how DOE analyzes hazards and implements controls at facilities that generate, process and store nuclear waste following the events at WIPP and INL in which waste drums released radiological materials due to energetic chemical reactions involving the waste.
The Board says it has identified the need for chemical compatibility evaluations for waste containers stored at waste generator sites that have not yet been certified for shipment to WIPP; the need to develop a defensible release fraction for energetic chemical reaction events based on the amount of material released in recent radiological release events; the need for improvements to control strategies to protect against energetic chemical reactions; and the need to revise DOE Standard 5506 to address these deficiencies.
The facilities studied by DNFSB staff in the report include the Plutonium Facility (PF-4), the Transuranic Waste Facility (TWF) and the Chemical and Metallurgical Research Facility (CMR), all of which are operated by Triad National Security, LLC, and Area G operated by N3B Los Alamos. The report found that the safety bases for these facilities do not appropriately analyze the hazards from potential energetic chemical reactions and reaction events involving transuranic waste.
The report states that LANL facilities safety bases do not contain a bounding analysis that accounts for the types of potential chemicals that could be present in waste drums or the amount of radiological material that could be released from an energetic chemical reaction event. Therefore the safety bases may not identify adequate safety controls to protect workers and the public.
Safety bases do not approach these issues in a consistent manner across LANL. Applying the assumed release fraction used in PF-4 and CMR to a maximally-loaded drum stored at TWF or Area G pending shipment to WIPP leads to a possible dose of 760 rem to a collocated worker and at Area G, a dose of 300 rem to the nearest members of the public.
Some 1,500 Area G containers have not undergone a chemical compatibility evaluation, the report claims, and some 2,000 containers do not meet WIPP acceptance criteria and will require remediation. The Area G safety basis is outdated and was developed in accordance with a DOE standard that requires less rigor for safety bases, the report says, and N3B has no immediate plans to update the safety basis to modern DOE requirements.
The report notes that some facilities rely primarily on the waste container to provide safety but that radiological release events that occurred at WIPP and INL demonstrated the importance of incorporating multiple layers of protection.
“Some LANL facilities such as PF4 and CMR provide multiple layers of protection including a confinement ventilation system and a fire suppression system to mitigate the consequences of a radiological release event. Other LANL facilities such as the outdoor transuranic waste storage pads at PF-4 and the fabric domes at Area G lack these safety systems,” the report says.
The report suggests that LANL could store higher risk waste containers such as poorly characterized waste, waste with high quantities of material at risk, waste that has not undergone a chemical compatibility evaluation or waste with incompatible chemical constituents in locations with more robust control sets and judiciously apply other types of controls such as over-pack containers, lid restraints and detection capabilities.
The full report may be viewed at https://www.dnfsb.gov/sites/default/files/document/21886/Tech-46%2C%20Potential%20Energetic%20Chemical%20Reaction%20Events%20Involving%20Transuranic%20Waste%20at%20LANL%20%5B2020-100-055%5D.pdf