Engineers improve reinforced steel to contain high-level nuclear waste



$ 2.5 trillion is spent globally to assess, mitigate and repair infrastructure corrosion, according to Penn State Assistant Professor Juan Pablo Gevaudan. He leads a team studying how to prevent its pervasive degradation.

Metals embedded in concrete can erode, rust and weaken until the concrete splits and the structure it supports falls. Such corrosion is considered one of the main issues that compounded the damage that led to the Surfside, Florida condominium collapse on June 24, 2021, according to the U.S. Department of Commerce. National Institute of Standards and Technology (NIST).

This corrosion is one of the biggest global challenges for infrastructure sustainability in all fields, according to Juan Pablo “JP” Gevaudan, assistant professor of architectural engineering and principal investigator of a grant of $ 800,000 over three years. of the US Department of Energy (DOE) University Nuclear Energy Program that will further explore the science of electrochemical corrosion degradation of concrete as it applies to high-level nuclear waste (HLNW).

Defined by the DOE as any radioactive material requiring permanent isolation, HLNWs can result from the treatment of nuclear fuel and produce radionuclides, radioactive atoms that are intrinsically unstable and harmful to life. Currently, HLNW is packaged in metal cans and embedded in concrete. Gévaudan collaborators include Andrea Argüelles, assistant professor of engineering and mechanics, and Rebecca Napolitano, assistant professor of architectural engineering.

“Understanding and preventing corrosion, especially in infrastructure, is one of our great global sustainability challenges,” said Gevaudan. “The science of concrete degradation applies to many areas of engineering, and we all want to improve our infrastructure. “

According to Gevaudan, when he and his collaborators learned about the challenges of end-of-life nuclear fuel cycles, they immediately saw a synergy between the goal of architectural engineering of improving the sustainability of the built environment and the The DOE’s goal to study corrosion in HLNW metal containers to extend the life of nuclear waste storage infrastructure. To extend this synergy across University Park, Gevaudan said, the team has already met with professors from the nuclear engineering department of Ken and Mary Alice Lindquist to identify areas where their work could align, and they plan to continue. their discussions on areas of convergent research. .

Ultrasonic-electrochemical impedance spectroscopy apparatus

The research team led by Gevaudan designed the world’s first ultrasonic electrochemical impedance spectroscopy device, known as UT-EIS, to non-destructively assess the corrosion resistance between new cement buffer materials. and containers for high-level nuclear waste. Credit: Penn State / Juan Pablo Gévaudan

“In this unique project, our goal is to create a new material capable of protecting HLNW metal containers, which contain the waste by-products of reactions that occur in nuclear reactors,” said Gevaudan. “We hope that we will develop a new cement-based buffer material that can immobilize harmful radionuclides which, in a critical situation, could escape from HLNW containers and prevent waste from reaching the environment and humans, thereby would be a disaster. ”

For this project, Gevaudan will leverage recent advances in its research group, the Responsive and Adaptive Infrastructure Materials (Re-AIM) research group, using organic and inorganic chemical interactions to develop modern and precisely engineered concrete materials. . To predict the degradation over time of these new buffer materials, Napolitano will create digital twins of systems to model proposed solutions and test potential results. Argüelles will use ultrasonic testing of the metal interface in a bespoke arrangement to non-destructively assess the corrosion potential of different formulations of buffer materials. Together, the team plans to spend the first 18 months of the grant period, which begins in October, developing concrete capable of binding the harmful wastes escaping from a reactor metal cartridge. Over the next 18 months, they plan to improve the buffer material to help prevent corrosion of the metal cartridge in the first place.

“They say reinforcing steel and concrete are best friends,” Gevaudan said. “The microstructural properties of concrete allow steel to develop a passive layer, a kind of protective shell that protects it from corrosion, but it can break down due to age or environmental stressors. The material we are developing will create a passive layer that will prevent corrosion for thousands, if not millions of years. “

To help achieve a durable and efficient material, Gevaudan said, the team is purchasing an automated reactor from Mettler Toledo, a company that produces precision instruments for a range of fields. With the reactor, researchers can synthesize modern cement materials with the desired properties under precisely controlled conditions with high repeatability. The machine also helps track the phases formed in new cements, allowing researchers to learn more about specific mineral configurations that change as the cementitious material is created.

“We will be able to quickly identify which phase best binds the radionuclides of interest, which will help us accelerate the development of the material,” said Gevaudan. “This grant allowed us to bring this cutting edge technology to cement research, which has traditionally used methodologies blocked in the past.”

The grant will also help fund student researchers who will work on the project as they complete their degrees in architectural engineering, chemical engineering, engineering, mechanics and acoustics, and other related disciplines. Gevaudan said the team is planning to grow and is particularly interested in students who are traditionally under-represented in engineering and pursue graduate studies.

“Besides the science, one of the most rewarding aspects of this project is building our team,” said Gevaudan. “This project symbolizes a group effort led by three early-career faculty members who are all under-represented in engineering. We have worked hard to secure this grant, and I am proud of the work we have done and will continue to do to combat steel corrosion in all disciplines, one of the most prevalent degradation problems that we have to meet.

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