More than a grain of salt

A new computing project helps make molten salt reactors a viable technology.

By Jake Bartman | November 29, 2023

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Research at Los Alamos may help make molten salt reactors, which use liquid salt as a coolant, into a viable technology. Los Alamos National Laboratory

Currently, every commercial nuclear reactor in the United States uses water as a coolant. Over the decades, however, researchers have designed reactors that use other substances instead. Oak Ridge National Laboratory’s Molten Salt Reactor Experiment (MSRE), which operated from 1965 to 1969, used salt as a coolant. In reactors like the MSRE, salt becomes molten (liquified by heat) as nuclear material that is dissolved within the salt fissions. The mixture then circulates to a heat exchanger, which can harness the fission heat to power a turbine and generate electricity.

Although MSRE succeeded in showing that molten salt reactors can work, the experiment also demonstrated some of the challenges that such reactors face. Most notably, the hot, salty, radioactive conditions inside the reactors can cause the metal that the reactors are made of to crack or corrode. 

No molten salt reactor has been built in the United States since the MSRE. However, in recent years, the Department of Energy (DOE) has begun again to research molten salt reactors, which, among other advantages, have the potential to be safer and more efficient than a typical light-water reactor.

Today, researchers at Los Alamos National Laboratory are helping to develop metals that can withstand the punishing atmosphere inside a molten salt reactor. One Los Alamos-led project, which is a part of DOE’s Scientific Discovery through Advanced Computing (SciDAC) program, is drawing together researchers from across disciplines and institutions—including Idaho, Lawrence Berkeley, and Sandia national laboratories, and Carnegie Mellon University—to achieve this goal.

Los Alamos’ Laurent Capolungo, who leads the project, says that experts in electrochemistry, applied mathematics, nuclear physics, and materials science are all contributing. “I don’t think I’ve ever seen a project that is as multidisciplinary as this one,” he says.

Capolungo’s team aims to develop a modeling framework that can predict the simultaneous effects of salt and radiation on nickel-based alloys, and understand how well such alloys will withstand these effects over decades of use. Achieving this goal would allow for the creation of metals that can be deployed in molten salt reactors without the need for years-long tests, facilitating the kind of rapid deployment necessary if the United States is to achieve the Biden administration goal of a carbon-pollution-free power sector by 2035.

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Nobel laureate Glenn Seaborg, who chaired the Atomic Energy Commission from 1961 to 1971, visited the Molten Salt Reactor Experiment in 1965.

According to Capolungo, Los Alamos is the right institution to lead the project because of its expertise in the multiphysics modeling that is central to the project’s research. The project relies on computer codes developed at Los Alamos and builds off the Los Alamos Reduced Order Model for advanced nonlinear equations (LAROMance), which Capolungo helped develop. Like the SciDAC project, LAROMance used computing to explore the response of metals to extreme environments.

In the first of the project’s five years of funding, researchers are refining key computer codes and building a roadmap for the future. They’re also fostering interdisciplinary dialogue to better understand the obstacles that the project faces.

“Without SciDAC, what we’re doing would be science fiction, not science,” Capolungo says. “We’re developing a new modeling framework that will plant the seeds for the next 20 years of research.” ★


Learn more about fission in Fission forward.