LANL Releases FTWC Final Report Volume 2 on Sampling, Plume Modeling

Los Alamos National Laboratory has released the second volume of its Flanged Tritium Waste Container Final Report, titled "Radioactive Air Emissions Summary, Volume 2, Environmental Sampling and Expanded Plume Modeling" (LA-UR-26-20967), documenting environmental sampling tied to the depressurization of four FTWCs that began on September 15, 2025 and took place over several days. The report presents soil sampling data, ambient air measurements taken during and after operations, and expanded plume modeling scenarios that compare stack emissions with air concentrations at downwind locations.

Volume 2 analyzes multiple plume-modeling variants, including different time frames of evaluation, different plume modes, and different age range scenarios, and explicitly compares modeled stack emissions to measured downwind air concentrations. The report states operational emissions for the entire depressurization were less than 123 curies and that a calculated off-site dose to a hypothetical Maximally Exposed Individual was less than 0.012 millirem; the laboratory materials note that a cross-country round-trip airplane flight results in about 3.7 mrem for context.

LANL’s Environmental Stewardship group, EPC-ES, led the soil sampling program and coordinated analytical work following EPC-ES procedures. Sampling began with early summer 2025 collections to represent pre-operational conditions, continued with weekly samples during the operations that started September 15, 2025, and concluded with a final set of samples after operations ended. The soil monitoring report, "Flanged Tritium Waste Container (FTWC) Soil Monitoring Methods and Results" by Gaukler, Shannon et al., was finalized December 8, 2025 and sent to RAEM staff. According to Volume 2 and the soil report, "None of the samples showed detectable tritium in the soil."

Air monitoring at LANL Airnet stations showed no change in tritium vapor concentrations during the FTWC activities, and the report’s conclusions state, "There were no measurable environmental effects from FTWC operations. There was no soil deposition measured, no change in tritium vapor concentrations measured at Airnet stations, [...]" Volume 2 also addresses requests from Environmental Protection Agency staff, responds to questions raised at FTWC public meetings, and fulfills criteria set by the New Mexico Environment Department.

NMED’s temporary authorization letter dated September 4, 2025, titled "Approval with Modifications of Temporary Authorization Request, Class 2 Permit Modification for Waste Treatment, Storage, and Repackaging of Four Flanged Tritium Waste Containers, HWB-LANL-19-033" and addressed to Theodore Wyka and Steven Coleman, required LANL to "publish a final report documenting the treatment process and all analytical results, including summaries of activities, lessons learned, and photographic documentation of the process." An independent technical review for the project conducted document reviews, onsite observations, and discussions with LANL tritium operations staff to weigh alternatives and inform operational planning; the review language clarifies terminology: "This report uses the term ‘depressurize’ to describe the controlled process to relieve pressure in the FTWCs headspace, i.e., controlled venting, and ‘vent’ to describe the unplanned, unmitigated release of pressure from the FTWCs."

LANL has said Volume 1 and other FTWC project documents are available on the LANL FTWC webpage, and LANL/NNSA indicated they will hold virtual and in-person public meetings to discuss the new report within the next couple of weeks; the lab directs inquiries to its public affairs office at media_relations@lanl.gov. LANL earlier noted Volume 2 would be issued in 2026, and the new LA-UR-26-20967 volume is now reported as complete and available to the public.