Research by City College of New York recently published in the journal of Nuclear Engineering and Design sheds new light on what happens when helium and air mix inside the reactor cavity of a high temperature gas reactor.
May 22, 2024
minute read time
Research recently published in the journal of Nuclear Engineering and Design sheds new light on what happens when helium and air mix inside the reactor cavity of a high temperature gas reactor.
According to the study, helium pipe breaks that occur higher up in a reactor cavity could reduce the likelihood of oxygen entering the core and causing damage.
The research findings will be used to inform the design and safety analysis of gas-cooled reactors.
The project was led by the City College of New York (CCNY) and builds on previous research supported by the U.S. Department of Energy (DOE).
Helium on the Rise
The CCNY research team built an experimental facility to mimic the performance of a gas-cooled reactor to test different helium pipe break scenarios.
Gas-cooled reactors offer enhanced safety features over current reactors and use robust TRISO fuel that can’t melt in commercial reactors. The reactors are designed to reach output temperatures as high as nearly 1,380 degrees Fahrenheit to efficiently produce heat for electricity generation or industrial applications.
Gas-cooled reactors use helium as a cooling agent and graphite to help stabilize the fission process inside the core. Graphite can withstand high temperature environments but could damage and oxidize if it’s exposed to air or water caused by pipe breaks or leaks.
Reactor pressure vessels are built to withstand design-basis events. However, reactor developers evaluate multiple layers of protection to ensure a complete understanding of a potential break in the pressure boundary.
Researchers found that pipe breaks higher up in the reactor cavity resulted in less heated helium and air mixing, resulting in lower concentrations of oxygen surrounding the location of the break that could reach the core.
Pipe breaks lower in the cavity resulted in higher mixtures of helium and oxygen and greater concentrations of oxygen near the pipe break that would increase the risk of potential core damage.
“By improving the understanding of helium coolant behavior in the reactor cavity under accident conditions, better high temperature gas reactor designs can be developed,” said Dr. Masahiro Kawaji, a nuclear engineering professor at CCNY. “This study will help reduce uncertainties in the evaluation and analysis of air-ingress scenarios.”
The project’s data will be submitted to the Nuclear Research Data System that reactor developers can access to help validate their computer codes that simulate how their designs will fare in similar helium pipe break scenarios.
The research was completed in collaboration with Idaho State University, Framatome, Idaho National Laboratory, University of Pittsburgh, Kansas State University and Purdue University.
The project received $800,000 in funding from the U.S. Department of Energy’s (DOE) Nuclear Energy University Program, which has provided more than $1 billion to U.S. colleges and universities to advance nuclear energy research, development and training since 2009.
The CCNY-led project complements earlier funded work through the program focused on heat transfer and natural circulation in high temperature gas reactors.
High temperature gas reactors are one of several concepts being supported through the Department of Energy’s Advanced Reactor Demonstration Program. Some designs could be deployed as early as this decade to support the nation’s economic and climate goals.
Learn more about our Nuclear Energy University Program.