Novel Cementitious Materials for the Next-Generation Infrastructure of Nuclear Waste Immobilization and Disposal.

The current design of repository infrastructure to safely contain, isolate, and dispose of high-level nuclear waste, such as heat-generating spent nuclear fuel (SNF), is limited in part by the materials available to construct this specialized infrastructure. Buffer materials, such as bentonite, surround the SNF metal canister to reduce interactions with the surrounding geological repository and limit the transport of any accidental radionuclide release. This crucial role is therefore an important consideration in the design of repository infrastructure. Bentonite clays have been considered good buffer materials; however, these limit infrastructure design due to their failure at temperatures above 100 °C. To mitigate this risk, costly practices have been adopted, such as surface storage of SNF packages, which requires 200-540 years to cool nuclear waste to acceptable levels. Thus, in addition to other bentonite limitations, there is a critical need to develop novel buffer materials that can enable robust repository designs.

With the goal to improve the safe containment, isolation, and disposal of SNF waste, this project aims to develop a novel cementitious buffer material (CBM) that can prevent corrosion of SNF packages and also immobilize fugitive radionuclides over long timescales (>106 years) in generic disposal concepts in salt, crystalline rock, or clay/shale repositories. To achieve this, the primary aim of this project is to identify and develop novel magnesium aluminophosphate (Mg-Al-P) CBMs, complete with assessments of their repository material stability as well as their transport and immobilization capacity of radionuclides. Additionally, given the accelerated corrosion of HLNW canisters, the secondary aim of the project is to employ advanced monitoring systems to understand the corrosive failure between the canister and CBM. The developed CBM and degradation science knowledge will contribute to the longterm performance understanding of the waste container-package through the creation of reliable digital twin models. Ultimately, this project will make significant strides to advance the robust design of the U.S. waste disposal infrastructure with greater capabilities to isolate and contain nuclear waste.

About the Responsive and Adaptive Infrastructure (Re-AIM) Research Group at The Pennsylvania State University:

The Responsive and Adaptive Infrastructure Materials (Re-AIM) research group led by Dr. Juan Pablo Gevaudan has the vision of helping achieve a symbiotic relationship between the built and natural environments by interrogating

(1) fundamental degradation mechanisms

(2) novel manufacturing routes

(3) durability engineering of cementitious materials. Our research aims to diversify the current choices of concrete technology by advancing fundamental and applied material science aspects for specific applications, such as extra-terrestrial buildings. Together we will “re-aim” the current paradigm, which prioritizes the use of prescriptive concrete technology, and develop “responsive” cementitious materials capable of adapting to harsh and local degradation conditions.

We are recruiting highly motivated students from a wide variety of fields to join the team (Architectural, Civil, or Environmental Engineering, Materials Science, Physics, Geochemistry, Architecture, Mechanical Engineering, and Chemistry). More specifically, fully funded opportunities are available to both national and international students. The team is looking for motivated students that have research experience in thermodynamic modelling, programming, and reactive transport for the development of digital twins of infrastructure. Underrepresented minority students in STEM are highly encouraged to apply.