US Oak Ridge National Laboratory (ORNL) has developed its first-ever custom glass test cell to observe how gases behave inside a molten salt reactor. The test cell will be used to better understand the complex chemistry that can occur in molten salt fuelled reactors. The data will be used to help verify existing computer codes and modelling software to better predict their overall performance.
Molten salt reactors are among several new systems under development that could be commercialised early next decade. Some designs will operate on liquid fuel, where the fissile materials are directly dissolved into a molten salt solution that is also used to cool the reactor.
Nuclear and chemical reactions from these designs can result in gases that bubble out of the molten salt. These can impact reactor neutronics and thermal hydraulic performance. To investigate this behaviour, ORNL researchers have designed and developed a customised glass test cell at the lab’s glass shop that can hold up to one litre of liquid molten salt.
The team then injected small helium and krypton bubbles into the cell to observe how they moved through the column. The experiment allowed researchers to observe and measure gas bubble velocity, size distribution, and interactions with neighbouring bubbles using high-speed cameras. This provided unique insights to help improve and validate simulation tools for molten-salt-fuelled systems.
“Understanding gas generation and transport in molten salt reactors is essential to optimising their performance and safety,” said Daniel Orea, ORNL’s lead R&D associate. “This unique glass test cell allows us to overcome certain engineering challenges caused by the high temperature and composition of salt and its two-phase liquid glass system.”
The research project was supported through the Department of Energy’s Molten Salt Reactor Programme that works to accelerate the research, development, and deployment of molten salt reactor technologies in the US.
