Advanced Material Development and Assessment of Cementitious Filler Materials for Long-Term Disposal of Nuclear Waste

How can concrete materials (the most utilized material in the world) offer unique solutions to the nuclear fuel cycle? How can we leverage modern cement chemistries to tailor material properties to satisfy nuclear waste disposal infrastructure requirements? How do radionuclides and corrosion of metal canisters occur in nuclear waste disposal filled with unique cementitious materials? This project seeks to answer these questions by developing new Mg-Al-P cementitious fillers (CFMs) to isolate and contain nuclear waste in canisters for a million years - a critical feat to provide the U.S. with new nuclear waste disposal strategies.

The goal of this project is to develop innovative CFMs to extend the safe containment of nuclear waste in dual purpose canisters (DPCs) over long time spans with improved permeability, neutron absorption, and dimensional stability. Extending upon recent advancements in DPC cementitious fillers development, the primary aim of this project is to characterize and formulate novel Mg-Al-P CFMs with assessments of their rheology and neutron absorption. Given the need to further understand CFM performance in breached canister scenarios emplaced in complex repository environments (i.e., argillaceous sedimentary rock, crystalline rock), the project’s secondary aim is to understand the pore structural changes due to repository groundwater flow. Furthermore, this aim seeks to characterize both the radionuclide binding and potential corrosion of metal neutron absorbers of existing DPC designs – a critical step to understanding post-closure criticality control and the capability of DPC disposal to isolate waste. Upon completion, this project will deliver complete knowledge of the rheological behavior and neutron dynamics as well as the in-repository environment performance of DPC cementitious fillers to increase confidence in the robustness of deep-mined disposal concepts. To this end, the project leverages rheometry-validated multi-physics simulations to reproduce with high-fidelity the cementitious material filling of DPCs – essential for the safe and technical implementation of DPC disposal. These innovative outcomes are essential for the continued operation of the U.S. reactor fleet as it develops key and cost-effective DPC disposal solutions for national fuel cycle strategy implementation.

   The innovative aims of this scientific study will be accomplished with three main research phases, namely: (Phase 1) formulation and characterization of phase assemblages and physical properties (i.e., expansion ratio) of Mg-Al-P CFMs via x-ray diffraction, thermogravimetric analysis, and Gibbs Minimization thermodynamic modelling; (Phase 2) rheological characterization of Mg-Al-P CFMs with unique reactor-rheology equipment to validate multi-physics simulations of DPC filling processes; (Phase 3) thermal neutron absorption and attenuation of developed Mg-Al-P mortar fillers at Breazeale Nuclear Reactor Facility neutron irradiation source; and, (Phase 4) assessment of the physio-chemical reactive transport of radionuclides (i.e., ¹³⁷Cs, ⁹⁰Sr, ²⁴³Am, ²³⁷Np, ⁹⁹Tc, ¹²⁹I) and of high-risk repository geochemical conditions (i.e., brine and groundwater flow) within Mg-Al-P pore networks via time-resolved micro-computerized tomography (4D µ-CT). These phases will leverage unique multi-disciplinary research facilities at the Pennsylvania State University, such as the Center for Quantitative Imaging – world-leading facilities for the characterization of time-based pore structure degradation mechanisms. Lastly, this research is supported by the Responsive and Adaptive Infrastructure Materials Laboratory - a unique cement chemistry laboratory for the in-depth characterization of new low-CO2 and sustainable cementitious materials - as well as the Materials Characterization Laboratory - world-renowned materials characterization multi-user facility with 50,000 square feet dedicated to current and future generations of characterization and fabrication tools.

Applying for this position:

If you are interested in this research for your Ph.D., we are looking for creative, curious, and gritty student researchers to join our team. Send the PI, Dr. Juan Pablo Gevaudan (e: jp.gevaudan@psu.edu), an email with your CV and a 1-2 page research interest statement where you explain your main research interests, your research approach, and how Penn State can help this research. Include a paragraph about how the envisioned Ph.D. project links to your vision, personal motivation, or career ambition. This will allow us to assess your research and professional development as well as the curiosity, critical thinking, and creativity that you will bring to our research group.