Making Safer Nuclear Reactors

Rensselaer Polytechnic Institute is leading a $3 million research project that will pair two of the world’s most powerful supercomputers to boost the safety and reliability of next-generation nuclear power reactors.

The three-year project, funded by the U.S. Department of Energy, will call upon a team of researchers and institutions to create highly detailed computer models of a proposed type of nuclear reactor. These models could play a key role for the development of the new reactors, which meet stringent safety and nonproliferation criteria, can burn long-lived and highly radioactive materials, and can operate over a long time without using new fuel.

Running simulations of such a vast virtual model, where scientists can watch the reactor system perform as a whole or zoom in to focus on the interaction of individual molecules, requires unprecedented computing power. To take on such a task, researchers will use both Rensselaer’s Computational Center for Nanotechnology Innovations (CCNI)—currently the world’s seventh-most powerful supercomputer—and Brookhaven National Laboratory’s New York Blue—the world’s fifth-most powerful supercomputer.

Rensselaer nuclear engineering and engineering physics professor Michael Podowski, a nuclear engineering and multiphase science and technology expert who also heads Rensselaer’s Interdisciplinary Center for Multiphase Research, is project director and principal investigator.

Podowski said nuclear power should likely gain traction and become more widespread in the coming decades, as nations seek ways to fulfill growing energy needs without increasing their greenhouse emissions. Nuclear reactors produce no carbon dioxide, Podowski said, which gives it an advantage over coal and other fossil fuels for large-scale electricity production.

The main challenge of nuclear power plants, he said, is that they produce radioactive waste as a byproduct of energy production. But several world governments, including the United States, are working with universities, research consortia and the private sector to design and develop safer nuclear reactors that produce less waste. These reactors will be necessary in the coming decades as nuclear reactors currently in use reach the end of their lifecycles and are gradually decommissioned.

The type of reactor that Podowski’s team will be modeling, a sodium-cooled fast reactor (SFR), is among the most promising of these next-generation designs. Its primary advantage is the ability to burn highly radioactive nuclear materials, which today’s reactors cannot do, Podowski said.

Whereas current reactors source their power from uranium, SFRs can source their power from a mixture of uranium and plutonium. In particular, SFRs will be able to burn both weapons-grade plutonium and pre-existing nuclear waste, Podowski said. Thanks to their high temperatures, SFRs also will produce electricity at higher efficiency than current nuclear reactors.

To expedite the understanding of the physics of the system, Podowski’s team will construct a detailed computer model of an SFR.

The researchers will use simulations to study fuel performance, local core degradation, fuel particle transport, and several other aspects of SFRs. By better understanding how design and operational issues will affect the reactor at different stages in its life cycle, Podowski said, the study will help improve the design and safety of SFRs before the first physical prototype is built.

“Nuclear reactors are safe, but nothing is perfect,” Podowski said. “So the issue is to anticipate what could happen, understand how it could happen and then take actions to both prevent it from happening and, in the extremely unlikely instance of an accident, be able to mitigate the consequences.”  EC


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