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Special Session: Basis for the design of multiscale/multiphase materials for nuclear waste management - 1
Time:
Thursday, 09/Nov/2023:
1:45pm - 2:45pm
Session Chair: Agnès GRANDJEAN Session Chair: Alban Gossard
Location:Lecture Hall
Session Abstract
Special Session: Basis for the design of multiscale/multiphase materials for nuclear waste management (organised by Agnes Grandjean, CEA, Marcoule France)
The goal of this session is to exchange information and discuss the challenges and limits of novel hierarchical structure materials for the creation of safe, efficient, and stable waste forms for fission products and transuranic elements. The efforts to generate the scientific basis for such waste forms will be presented including materials synthesis, characterization, modeling, and radiation effects. The long-term behavior of nuclear waste form materials under high radiation fluxes and the reliable containment of radionuclides within their structure are key issues for safe and successful nuclear waste management. The development of waste form materials with structural flexibility at various scales (from atomic to micrometer) for targeted compositions and phases offers a unique opportunity to achieve the safe and sustainable storage of nuclear waste. This is enabled by advances in the chemical/structural understanding of innovative hierarchical structure motifs able to incorporate transuranic or fission products elements, such as salt inclusion materials, metal organic frameworks, tunnel structures, and multi-scale porous structures. The activities of necessity include investigation and development direct and indirect synthesis routes to obtain structure motifs for hosting specific elements these will be discussed as will fundamental transport process in multi-scale porous and hierarchical materials. The expected scientific exchange will allow the advancement of the understanding of waste form materials, will strengthen the research potential, and ultimately generate solutions to meet the existing challenges of advanced waste forms.
Presentations
1:45pm - 2:15pm
Metal Organic Frameworks for Off-gas Management
Praveen K Thallapally, Patricia D Paviet
Pacific Northwest National Laboratory, United States of America
Separation of volatile radionuclides including Iodine and noble gases from the off-gas streams of a used nuclear fuel reprocessing facility or advanced reactors has been a topic of significant research. The current technology uses energy intensive cryogenic distillation, which is expensive. Another downside of this approach is the accumulation of ozone due to radiolysis of oxygen. Therefore, alternate technologies, and associated materials, are needed for separation of noble gases selectively over other gases including CO2, N2, O2 and Ar. Pacific Northwest National Laboratory is exploring a new class of materials called metal organic frameworks for separation of noble gases selectively at near room temperature. Our laboratory results demonstrate the removal of these gases with high adsorption capacity and selectivity compared to benchmark materials, such as zeolites and activated carbons. The high selectivity towards noble gases over other gases at low concentration indicates the perfect match between the pore size and the kinetic diameter of the gas species. In this talk I will focus on recent results from our laboratory on separation of noble gases at near room temperature using porous metal organic frameworks.
2:15pm - 2:45pm
Crystal Growth of Actinide Materials as Potential Nuclear Waste Forms
Hans-Conrad zur Loye
University of South Carolina, United States of America
A nuclear waste form is a stable, solid matrix for the immobilization of radioactive and hazardous constituents present in nuclear waste. There are a variety of waste forms currently in use and many more being studied for potential use. Or center is developing new materials as potential waste forms. To achieve this goal we are preparing and testing numerous actinide containing materials. I will present some of our efforts focussing on the crystal growth of uranium and transuranium containing phases via two different crystal growth routes, mild hydrothermal and high temperature solution flux growth and their evaluation as potential waste forms. The mild hydrothermal route works extremely well for crystallizing complex fluoride phases, such as Na3GaUIV6F30, Na3AlNpIV6F30, andNa3FePuIV6F30, while the high temperature flux route works well for crystallizing oxide phases, such as Cs2PuIVSi6O15 and Na2PuVO2(BO3). The synthesis and structures of these phases as well as a series of new chalcogenides will be discussed, along with our appraoch of identifying potential compositions that we can pursue synthetically.
