New process speeds up development of molten salt nuclear battery

20 May 2021

The US University of Idaho said on 17 May that researchers had verified a new process to save millions of dollars and speed up development of the world’s first Molten Salt Nuclear Battery (MsNB). Generating energy from nuclear fuel dissolved in molten salt offers improved safety and efficiency, and research is ongoing to bring this technology to market. Salt is not combustible and has a low volatility, removing risk of vessel rupture from pressure build-up.

“This is a monumental step in the molten salt reactor design process,” said University of Idaho Engineering Director Rich Christensen, “So many military bases, hospitals and communities rely on secure, continuous energy from a standard grid. If that grid goes down, all these critical areas suffer.” He added that the MsNB provides a small, distributed energy source, bringing autonomy to institutions once dependent on a central power source.

A new testing device physically validates the MsNB as an improved, more reliable and cost-effective molten salt reactor for its ability to naturally circulate liquid fuel. The device was conceived by Tennessee-based nuclear power company Micro Nuclear CEO Paul Marotta, Idaho National Laboratory (INL) Research Scientist Piyush Sabharwall and Christensen. It is expected to save millions in testing costs and to reduce MsNB’s development timeline by two years.

The testing device uses ohmic heating to evenly heat liquid via an electric current. It acts as a reactor surrogate, mimicking the internal heat generation that would occur within a reactor through fission, or the splitting of an atom’s nucleus. In the MsNB, heat released during the ohmic heating testing process causes the molten salt fuel within the battery to rise in a central cylinder. Once at the top, the fuel moves to a heat exchanger, where it is cooled and falls back down the space between inner and outer cylinders. This natural circulation eliminates the need for valves and pumps, improving the reliability and simplicity of the reactor design.

The ohmically heated reactor surrogate, constructed by Blackfoot contractor Premier Technology, also allows researchers such as Christensen and University of Idaho students to easily physically validate computer simulations, reducing overall testing cost. A patent is being filed on the concept’s application to natural circulation in NPPs. With a 10-year lifespan, the MsNB would allow for easy factory construction and transport of reactors to remote areas to support critical infrastructure with electricity and heat. When the battery dies, Christensen said, the device can be shipped back to the factory to be recycled or for disposal.

A US Department of Energy grant proposal has been submitted by Micro Nuclear, Premier Technology, INL and a consortium of eight universities led by University of Idaho. If awarded, funding will go toward validation and completion of an initial MsNB design, including manufacturing at Premier Technology.

“This is a collaborative effort to develop advanced nuclear technology that can support critical health and security infrastructure,” said Ashley Finan, National Reactor Innovation Centre (NRIC) director, “NRIC is ready to partner with the team to make this demonstration a success.”

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