TRUEX

TRUEX
Name	TRUEX
Type	solvent extraction process
Developer	Argonne National Laboratory
Application	nuclear waste separations
Introduced	1990s
Country	United States

TRUEX

TRUEX is an advanced solvent-extraction process developed to separate transuranic elements and selected fission products from high-level radioactive wastes. It was designed to complement other partitioning schemes and to reduce the long-term radiotoxicity and heat load of waste destined for geological repositories. The technology integrates chemical engineering, radiochemistry, and separations science to target actinides such as plutonium and americium while allowing facile integration with processes used at sites such as Hanford Site, Savannah River Site, and Idaho National Laboratory.

Overview

TRUEX was developed to enable partitioning of actinides from acidic aqueous waste streams into an organic solvent phase for subsequent recovery and conditioning. The process is rooted in principles established by earlier programs at Oak Ridge National Laboratory, Los Alamos National Laboratory, and Brookhaven National Laboratory and was advanced at Argonne National Laboratory in collaboration with the U.S. Department of Energy. It is often discussed alongside other separation schemes such as the PUREX process, TALSPEAK process, DIAMEX process, and SANEX process in literature addressing nuclear fuel cycle management. TRUEX can be interfaced with vitrification campaigns at facilities like West Valley Demonstration Project and research campaigns at Institut Laue-Langevin and CEA laboratories.

Process Chemistry

TRUEX chemistry exploits complexation and solvating extraction using organophosphorus and nitrogenous extractants dissolved in hydrocarbon diluents. The principal extractant is octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO), often combined with tri-n-butyl phosphate (TBP) or diisopropylbiphenyl diluents studied at Chevron and ExxonMobil laboratories for solvent stability. The aqueous phase is typically a strong nitric acid matrix similar to streams from La Hague and Sellafield reprocessing campaigns. Metal ions such as plutonium, americium, curium, and certain lanthanides form neutral or cationic complexes with CMPO and co-extract depending on oxidation state and complexing agents. Chelators like ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) have been explored in related processes at Los Alamos and Oak Ridge to modulate distribution ratios. Redox control using agents characterized in studies at Argonne National Laboratory and Pacific Northwest National Laboratory is critical to keep plutonium in extractable oxidation states. Back-extraction (stripping) methods employ complexing agents or pH adjustment techniques developed in coordination with researchers from MIT and University of Tokyo.

Applications

TRUEX has been applied in pilot-scale campaigns for partitioning transuranic elements from legacy wastes at sites including Rocky Flats Plant, Hanford Site, and Savannah River Site. It serves as a candidate unit operation in proposed advanced fuel cycles discussed by organizations such as the Nuclear Energy Agency and International Atomic Energy Agency. Beyond waste minimization, TRUEX principles inform programs in radioisotope purification for medical isotopes produced at facilities like Brookhaven National Laboratory and Los Alamos National Laboratory. The process has been evaluated for integration with molten salt reactor fuel reprocessing concepts studied by Idaho National Laboratory and reactor fuel cycle proposals from Electric Power Research Institute and national laboratories in France and Japan.

Performance and Efficiency

Laboratory and engineering-scale studies at Argonne National Laboratory and Pacific Northwest National Laboratory have quantified distribution coefficients, separation factors, and loading capacities for TRUEX solvents. Performance metrics indicate high decontamination factors for actinides relative to bulk fission products such as cesium-137 and strontium-90 when coupled with upstream cesium removal systems like AMP/PEI or Crystalline Silicotitanate sorbents. Solvent phase stability, phase disengagement time, and radiolytic degradation rates were benchmarked in interlaboratory exercises involving Oak Ridge National Laboratory, Lawrence Livermore National Laboratory, and industrial partners such as Areva and Westinghouse. Process efficiency depends on solvent composition, contact stages, and hydrodynamics modeled using tools developed at University of California, Berkeley and Imperial College London.

Safety and Environmental Considerations

TRUEX operations must address criticality safety concerns for fissile actinides, following standards promulgated by Nuclear Regulatory Commission and technical guidelines from American Nuclear Society. Radiolysis of organic solvents and generation of secondary wastes require mitigation strategies informed by research at Argonne National Laboratory and industrial radiochemistry divisions of Shell and BP. Solvent fires and flammability are managed through engineering controls similar to those at Sellafield facilities, and process emissions are regulated under frameworks associated with Environmental Protection Agency and international accords addressed by International Atomic Energy Agency. Life-cycle assessments comparing partitioning schemes to direct vitrification have been performed by teams at MIT, Northwestern University, and University of Manchester.

Development and History

TRUEX emerged from 1980s–1990s research initiatives at Argonne National Laboratory building on extraction science from Oak Ridge National Laboratory and collaborative programs funded by the U.S. Department of Energy. Pilot demonstrations and interagency studies involved researchers from Los Alamos National Laboratory, Brookhaven National Laboratory, Pacific Northwest National Laboratory, and academic partners including University of Michigan and Colorado School of Mines. International interest prompted evaluations by agencies and companies in France, Japan, United Kingdom, and Germany, with comparative studies versus DIAMEX and SANEX processes. Continuing work addresses solvent formulation, radiolytic resilience, and integration into advanced fuel cycles championed by consortia including the Generation IV International Forum and the Nuclear Energy Agency.

Category:Radioactive waste management