Progressive Solutions to Improve Corrosion Resistance for Nuclear Waste Storage: On-Demand Alternative Nuclear Waste Storage Materials and New Imaging Neutron Microscopy Technique for Nuclear Waste Storage Glass Corroded in Aqueous Solution
Sponsored by: TMS Corrosion and Environmental Effects Committee, ACerS Glass & Optical Materials Division
Program Organizers: Madeleine Jordache, Stevens Institute of Technology; Gary Pickrell, Virginia Tech
Friday 8:00 AM
October 22, 2021
Room: On-Demand Room 9
Location: MS&T On Demand
Session Chair: Madeleine Jordache, Stevens Institute of Technology; Gary Pickrell, Virginia Tech
Introductory Comments: Madeleine Jordache1; 1Stevens Institute of Technology
Invited
Particulars of Crystallization of Glass-ceramics for Nuclear Waste Storage: Edgar Zanotto1; 1Federal University of Sao Carlos
Safe nuclear waste storage (NWS) is a crucial problem related to the increasing world demand for sustainable energy. Glasses and glass-ceramics are top candidates for NWS, with over 4,000 studies performed since 1959. Reported crystal phases include pyrochlore, zirconolite, powellite, oxyapatite, NaZr2(PO4)3, ZrP2O7, FePO4, sphene, and CaTiO3.They must have a formidable combination of properties: adequate glass-forming ability to suppress spontaneous crystallization, crystallize into phases and a residual glass of high chemical durability, dissolve high amounts of different radioactive elements in the crystal phases, and be stable against further crystallization during storage. In this talk, we will show positive features and difficulties regarding the application of nucleation and growth models to understand, describe and predict the crystallization kinetics and crystallization pathways of elaborate, non-stoichiometric oxide formulations such as those intended for NWS. We will discuss some relevant open issues: crystallization-induced pores, spontaneous cracking, thermal and microstructural gradients in monolithic pieces.
Invited
Neutron Microscope Based on Wolter Optics for Imaging Hydrogen Distribution in Glass: Boris Khaykovich1; Daniel Hussey2; Suzanne Romaine3; Kiranmayee Kilaru4; Brian Ramsey4; 1Massachusetts Institute Of Technology; 2NIST; 3Harvard-Smithsonian Center for Astrophysics; 4NASA
Neutron radiography is particularly suitable for elucidating the spatial distribution of hydrogen in samples with spatial resolution down to a few micrometers. However, neutron sources are inherently very weak, while neutrons are difficult to focus so that neutron imaging beamlines are built as pinhole cameras. While the spatial resolution scales as D/L (D~1 cm is the pinhole diameter and L~10 m is the pinhole-to-detector distance), the neutron fluence rate at the sample position scales as (D/L)2. Therefore, achieving a resolution of a few microns may require many hours of exposure precluding measurements of materials with fast hydrogen mobility or comparing samples with variable compositions. Focusing mirrors promise to solve these problems by improving the time resolution of the method by at least a factor of 1,000. I will describe the Wolter optics system that will be first available at NIST in 2022, and neutron imaging at the MIT Nuclear reactor.