| Scope |
Scope: To increase the Corrosion Resistance of Nuclear Waste Forms’ Materials in permanent and temporary storage to Restrict Radionuclides Escapes in subterrain waters.
The symposium will enclose two topics:
1) Improvement of Nuclear Waste Immobilization Glasses’ (Borosilicate, Iron Phosphate, Aluminophosphate Glasses) Long-term Durability at their final disposal at the Geological Repository (GR), through fully understanding their Aqueous Corrosion Behavior and the relevant Mechanical Properties (especially Toughness and Strength) to Corrosion, for increasing and predicting their Aqueous Corrosion Resistance. We seek studies of the Parameters that control Glass’s Mechanical Properties of interest, as they arise from Composition, Processing and Structure. Research on means to increase nuclear waste loading, formability, radiation stability and radiation shielding of the environment are of interest. Consideration of the whole permanent storage system at the GR, and the processes taking place within, including the aqueous corrosion of the waste forms due to infiltrated water, the waste forms geochemical interactions with the host rocks, as well as the near-field evolution is sought for.
We consider two different Nuclear Waste Forms Systems at the Geological Repository:
a) Stand-alone vitreous waste forms made of Iron Phosphate Glass that also in the meantime immobilizes the nuclear waste.
b) Borosilicate, Iron Phosphate or Aluminophosphate Glass immobilizing the Nuclear Waste enclosed in Metallic Canisters.
2) Improvement of Metallic Canisters’ Nuclear Waste Forms:
a) For temporary storage, Stainless Steel Canisters for Spent Nuclear Fuel, understanding Chloride Induced Stress Corrosion Cracking (CISCC) and means to mitigate it: such as cold sprayed with the same type of steel used for canisters or with Ni and Ti coatings on Stainless Steel 304L, or polymer derived ceramic coatings: SiON and SiOCN on AISI 304 Stainless Steel. Evaluate comparatively the susceptibility to CISCC of 316L Stainless Steel Welds produced by different welding techniques methods such as Gas Tungsten Arc (conventional high heat) and Laser (modern high density, low heat input methods), which result in very different alteration of Microstructure and Residual Stresses. Measurement of the Residual Stress in Welds of Stainless-Steel Canisters produced by Additive Manufacturing, suitable for large and complex structures, such as Wire Arc Direct Deposition and by classical technology. Increasing and predicting the SS Canisters’ resistance to CISCC.
b) For permanent storage, Corrosion Resistant Alloys (CRA): Stainless Steel, Ni based alloys, such as Ni-Cr alloys, through atomic understanding the underlying physics that controls the aqueous corrosion of metals, means to mitigate it, models to reliably predict the transition from passivation to corrosion. Looking on a radionuclide transport mechanism upon a hypothetical leakage from the metallic canister at the GR, at its interaction with the host rock formation, at the influence of the geochemical environment, including understanding the near-field components and processes in their evolution: canister-bentonite interactions and corrosion evolution.
Correlation Composition-Processing-Structure-Properties are sought for.
Modelling Corrosion and Mechanical Properties by Atomistic Simulations, Quantitative Structure-Property Relationship (QSPR) analysis, Machine Learning (ML), Physics based, and Artificial Intelligence (AI). Designing Nuclear Waste Forms, including through Informatics-driven approach for waste forms to immobilize waste streams for water cooled, and especially molten salts nuclear reactors, which are under continuous development at the present time. Designing Iron Phosphate Vitreous Forms as Stand-alone Containers, and Borosilicate, Aluminum and/or Iron Phosphate Glasses Nuclear Waste Forms to be contained in Metallic Containers for final storage and Improving Stainless Steel Canisters for temporary storage.
Experimental work to further investigate details of the Materials’ Corrosion process, as well as details of the structure of Glasses that immobilize radionuclides and Evaluate and Investigate means to Improve relevant (to corrosion) mechanical Properties of the Vitreous Waste Forms.
Developments in the Characterization Techniques of the Nuclear Waste Forms’ Microstructure and Atomic Structure and their Changes during the Corrosion process, such as Neutron Diffraction (also for Measurement of the Residual Stress in the Waste Forms), High-energy X-ray Diffraction (HEXD), , X-ray Diffraction (XRD), Nuclear Magnetic Resonance (NMR), Spectroscopy (Raman, Infrared, Terahertz, Mosbauer, X-ray Absorption Spectroscopy (XAS) with subsets Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES), Energy Dispersive, X-ray Photoelectron (XPS)), Electron Microscopy (including 4DSTEM), Atom Probe Tomography vs. NanoSims for unraveling glasses’ aqueous corrosion mechanism. |