Nuclear energy materials

Overview

The ability to predict the radiation tolerance of materials in extreme environments plays a key role in research at LLNL regarding strategies to extend the lifetime of our nation’s nuclear power plants—and identify materials for the next generation of nuclear reactors and fusion power plants.

With this aim in mind, our materials science experts use research instruments at CAMS to emulate the damage that materials in nuclear reactors and in fusion power plants could experience in response to radiation. Following the experiments at CAMS, scientists examine microstructural and bulk physical property changes to the materials, enabling them to better understand the mechanisms of radiation damage on the materials and how microstructural changes caused by radiation might impact long-term safety and performance.

Conventional reactor materials

LLNL scientists and collaborators study how the extreme conditions found in nuclear reactors affect the strength and structure of materials used in these reactors, including steel and nickel-based alloys, causing the materials to become brittle and more likely to fracture. The ion irradiation techniques available at CAMS enable scientists to study how radiation affects the structural components of a nuclear reactor over time, and how an accumulation of defects can impact the material’s microstructure—thereby impacting the plant’s performance and lifetime.

For example, we study how material responds to various radiation doses, which can cause the material to soften and deform. We leverage the ion-beam irradiation capabilities at CAMS to simulate the environment found in nuclear reactors, including temperatures and radiation doses. In addition, our research teams use transmission electron microscopy and atom probe tomography to characterize changes to the material, along with scanning electron microscopy testing, to help identify correlations between the material’s instability and resulting deformations. With this data, we can explore the types of defects caused by the radiation, as well as changes to specific microstructural features, such as grain boundaries.

In related work, we study how steel material used in nuclear reactors performs at elevated temperatures. Steel material is frequently used in reactors’ heat exchangers and steam generators, and researchers are therefore interested in understanding its long-term performance in high-temperature environments. LLNL scientists and their collaborators conducted micro-compression testing of steel materials at elevated temperatures to quantify its mechanical properties and observe deformation mechanisms. We first irradiated samples using ion beams at CAMS, and then we performed micro-compression testing of the samples at different temperatures.

Key collaborator: Our research regarding nuclear reactor materials involves collaborators from several other national labs, as well as researchers from the University of Michigan and two University of California campuses. Many of our collaborators benefit from access to CAMS through the Nuclear Science User Facilities (NSUF) network, funded by the U.S. Department of Energy.

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Fusion energy materials

LLNL scientists are studying the radiation tolerance of materials used in extreme fusion energy environments. For example, our research teams are exploring how alloy complexity and operating conditions affect the survivability of materials used in fusion power plants. We combine experimental efforts and predictive simulations to study radiation defects in complex alloys (e.g., swelling and hardening), as we focus on discovering and designing radiation-tolerant materials with the stability and structural integrity needed to survive in fusion chambers.

We leverage experimental capabilities at CAMS to conduct irradiation experiments on new types of alloys, and then characterize the radiation’s impact on the materials. Data generated by these experiments at CAMS is fed into our models to accelerate discovery of possible solutions—materials with the microstructure needed to survive in fusion power plants.

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