Industry partners advance nuclear tech with molten salt

Idaho National Laboratory, MicroNuclear LLC, The University of Idaho, and other partners are advancing nuclear reactor technology with newly developed testing — and plans for a future product — using molten salt as heat and fuel.

The University of Idaho (Idaho Falls) has designed and tested a testing device that closely simulates how molten salt behaves, including in nuclear reactors. The next step is to test it at a larger scale. By advancing the testing, project members said, this will expedite and improve the development of nuclear reactors powered by molten salt.

INL and MicroNuclear will help with the testing and creation of devices.

“We’ll be using the real stuff, to see the real effects,” said Piyush Sabharwall, senior research scientist at INL. Testing at a larger scale is important, he added, because “We still need to prove quite a few things.”

And, questions could arise.

“If it didn’t work at a bigger scale, why didn’t it work,” Sabharwall posed, because the physics remain the same. It is more efficient and cost-effective to make changes at this level, project members said, and avoids complication further in development.

Sabharwall is confident that significant progress will be made in the anticipated few years of model testing.

“Experiments are very essential to validate the models,” Sahbarwall said.

The group is hopeful for grant approval from the U.S. Department of Energy that would help fund creation and testing of devices using the molten salt technology. If approved, the grant would fund 80% of the project’s costs. Project members expect to find out in December or January.

“If the grant is awarded, then the plan would be that a reactor would be built,” said Rich Christensen, U of I, Idaho Falls nuclear engineering director. An intermediate model and final model are planned to be built and tested at INL.

If the project does not receive the grant funding, “We do not intend on giving up,” Christensen said.

“This is a reactor system that is very simple, safe, and we’d pursue other funding mechanisms,” Christensen said. “We anticipate pushing forward because we feel it has great promise and it can add to the portfolio the country has today.”

One aspect that makes this testing technology important is the versatility it has across industries (not just nuclear energy) and research institutions. Seven other universities are on board in supporting, and using, the testing technology.

The testing device, designed by Christensen, uses “ohmic heating” to evenly heat liquid via an electric current, according to a press release. The fluid itself is heated, rather than the traditional approach of heating a solid object that then heats the fuel.

“The Ohmic Heating concept used in the testing actually flowed from the review of a technical Journal Article focused on food processing,” MicroNuclear CEO Paul Marotta said in an email. “So, I would characterize MicroNuclear’s role as concept initiator, or, idea generator, then worked in close collaboration with a tremendously talented group of colleagues to make it a reality.”

It acts as a reactor surrogate, project members explained in the press release, mimicking the internal heat generation that would occur within a reactor through fission, or the splitting of an atom’s nucleus.

“Having this device lets us go in and ascertain exactly what the fluid is doing inside the reactor,” Christensen said. “That lets us make our designs a little bit more exact, by making (the device) more exact, then they are safer.”

The nuclear energy reactor, referred to as the Molten Salt Nuclear Battery, would generate heat and produce electricity.

In the Molten Salt Nuclear Battery, heat released during the ohmic heating testing process causes the molten salt fuel within the battery to rise in a central cylinder, the press release stated. 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, Inc., also allows researchers to easily physically validate computer simulations, according to the release, which reduces overall testing cost.

A patent is pending.

“There is a lot of value nuclear provides,” said Sabhawall. “I’m really passionate about this field because of the value it has for the future.”

The passion behind the project

One of the values in the Molten Salt Nuclear Battery technology is the autonomy it would provide to military bases, hospitals and similar institutions.

“All these institutes … they have critical infrastructure that they don’t want to go down, or they don’t want to have that facility out of commission, and right now most of the military bases are connected to the standard grid,” Christensen said. “You need a backup power source, that you control, and if the whole grid goes down, you still have power.”

Military operations often rely on diesel fuel backup generators, and that fuel could cause hang-ups, Christensen and other experts say. The molten salt nuclear battery would provide fuel for about 10 years of operation.

When compared to similar projects at INL, this testing device and ultimate Molten Salt Nuclear Battery would operate with much higher temperatures, Sabharwall said.

“They’re all reactors, it’s their footprint, how much capacity do they have; each has their own role; they are all valuable,” Sabharwall said. “We need all of them.”

“It’s hard to see sometimes, but this project demonstrates that the core ability to create and innovate is alive and well in the U.S.,” Marotta wrote. “We just need to facilitate more of it.”

Sabharwall added he hopes people will keep an open mind when they look at nuclear reactor technology, as “the most important thing behind any project is the intention.” And, he invites open dialogue.

He quoted previous leadership within the energy industry, who stated wind, solar, nuclear each have a role to play; there’s no competition.

And, for those like Sabharwall, when they all come together, and everyone believes in each other, everyone wins.

“We are responsible to the future generations,” Sabharwall said. “We have to look at the role we can play going beyond today.”