This article is part of a series covering Idaho National Laboratory (INL). Scroll visited different projects from INL, and this publication covers the MARVEL microreactor located west of Idaho Falls.

When Hurricane Florence made landfall in my small hometown in coastal North Carolina, we lost power within the first hour of the storm. The power outage lasted for six days as we sweltered in the heat of summer, with only an old generator to power a single fan and a small fridge used to keep my type-one diabetic brother’s insulin cold.

But imagine, along with the emergency response vehicles and personnel, there was a machine that could independently restore power in the area, and continue to power it for ten years.

INL is currently working on a first-of-its-kind technology called MARVEL that will play a leading role in advancing the research and development of nuclear microreactors that can be used to power communities like mine.

What is a microreactor?

A microreactor is a miniaturized version of a nuclear reactor. It is intended to make nuclear power a more portable and accessible energy source. This makes the concept ideal for military operations or remote communities that need to generate power on-site.

According to the INL website, “Microreactors are 100 to 1,000 times smaller than conventional nuclear reactors.” Microreactors are also self-regulating, meaning they need a much smaller crew of operators, have a higher safety profile, can operate for multiple years without refueling and can be used with other energy sources.

“Recently, there’s ​been ​a ​wave ​of ​excitement ​over ​microreactor ​technology ​because ​of ​everything ​it ​offers,” said John Jackson, the national technical director for the Energy Department’s microreactor program. “​It ​offers ​simplicity. ​It ​offers ​adaptability. ​It ​offers ​resilience. It ​offers ​a ​rapid ​path ​to ​specific ​energy ​solutions ​in ​the ​broader ​portfolio ​that ​includes ​light water ​reactors, ​the ​conventional ​reactors ​that ​you’re ​used ​to ​seeing predominantly ​in ​the ​Southeast ​of ​the ​United ​States … ​it’s ​a ​very ​​valuable ​piece ​of ​our ​energy ​portfolio.”

Rendering and design of MARVEL that is expected to be completed in the next few years. Photo credit: Idaho National Labratory

The work being done on microreactors by INL is critical for establishing the feasibility of implementing this technology.

“We ​do ​this ​for ​the ​benefit ​of ​the ​United ​States ​of ​America ​and ​for ​the ​tax-paying ​community,” Jackson said. ​”The ​bottom ​line ​is … ​there ​are ​no ​microreactors ​that ​are ​commercially ​deployed ​at ​this ​point. ​​So, ​it’s ​very ​beneficial ​and ​it’s ​the ​mandate ​of ​the ​national ​laboratories ​to ​step ​up and ​assume ​some ​of ​that ​inherent ​risk.”

What is MARVEL?

MARVEL stands for Microreactor ​Applications, ​Research, ​Validation ​and ​Evaluation. This is the microreactor that INL has been working on designing and developing since 2020.

“The ​primary ​goal ​is ​to ​build ​a real ​microreactor ​and ​make ​it ​operational ​as ​rapidly ​and ​as ​inexpensively ​as ​possible,” Jackson said.

While MARVEL is not the only microreactor being developed in the U.S., it does have unique components that set it apart from similar projects. Many reactors use water as a cooling component, like INL’s Advanced Test Reactor, but MARVEL will be a “liquid metal” or sodium-potassium-cooled reactor. It also uses off-the-shelf components, such as Stirling engines, as a power source.

Vintage signage at the EBR-I Atomic Museum that demonstrates precautions used in nuclear power facilities. Photo credit: Gabriela Fletcher

Standing at roughly 15 feet and 8 feet in diameter, MARVEL is a relatively small microreactor but will be expected to generate about 100 kilowatts of power. MARVEL will be built in the Transient Reactor Test Facility (TREAT) at INL and eventually will be used in coordination with wind and solar energy sources to power a small microgrid.

Current progress in MARVEL’s development

Recently, engineers reached a monumental milestone in the development of MARVEL.

“We ​achieved ​what’s ​referred ​to ​as ​90% ​final ​design,” Jackson said. “This ​is ​the ​first ​time ​the ​Department ​of ​Energy ​has ​taken ​a ​design ​to ​90% ​final ​design ​threshold, ​so ​we’re ​truly ​making ​history ​already ​with ​this … ​​We ​now ​have ​all ​the ​engineering ​drawings ​and ​all ​the engineering ​specifications ​necessary ​to ​construct ​and ​fabricate so ​it ​means ​MARVEL ​will ​become ​a ​reality.”

Reaching 90% final design means that there is now only a 10% margin of error left of work out any issues that may arise while bridging the gap between the idea for the design and the actual fabrication of MARVEL.

According to the Office of Nuclear Energy website, “INL built the full-scale, electrically heated prototype (of MARVEL), known as the primary coolant apparatus test or PCAT, last year.”

Rendering of MARVEL and how it will be installed at TREAT. Photo credit: Idaho National Labratory

The PCAT will be powered by electricity rather than nuclear fission to gain data on how MARVEL will function and what adjustments can be made to improve it.

There is no specific timeline for when the project will be completed. At this stage, Jackson says it is expected to come online in the next few years. According to an INL fact sheet on the project, it is anticipated to operate for about two years once the system begins running.

The role of nuclear power in clean energy

Nuclear power is fueled by uranium atoms being split in a process called fission, which generates heat and energy. This makes nuclear power a zero-emission energy source and a good option for clean and sustainable energy.

Uranium is an extremely dense fuel for nuclear power. According to the Office of Energy website, one 1-inch uranium pellet can produce an amount of energy equivalent to 120 gallons of oil or 1 ton of coal.

Data from Pew Research Center shows that the number of people in favor of more nuclear power is growing, and 57% showed interest in increasing the number of nuclear power plants for energy compared to wind and solar power.

Map of INL facilities in the area displayed at the EBR-I Atomic Museum. Photo credit: Gabriela Fletcher

“The ​problem ​with ​wind ​and ​solar ​is ​they ​are ​intermittent,” Jackson said. “​The ​reality ​is ​we ​need ​to ​utilize ​all ​of ​the ​energy ​sources ​that ​we ​have ​access ​to. ​The ​simple ​fact ​of ​the ​matter ​is ​that ​as ​we ​become ​more ​technologically ​advanced, ​we ​use ​energy ​in ​massive ​amounts. ​So ​in ​order ​to ​meet ​the ​demand, ​most ​people ​who ​look ​at ​the ​mathematics ​of ​this ​situation ​understand ​that ​you ​must ​utilize ​nuclear ​energy ​to ​get ​there.”