Testing is underway for an electric-powered prototype of the MARVEL microreactor developed by the U.S. Department of Energy at Idaho National Laboratory (INL) to help advance new reactor technologies.
September 20, 2023

Testing is underway for an electric-powered microreactor prototype developed by the U.S. Department of Energy.
The 12-foot-tall machine is a full-scale replica of the Department’s MARVEL microreactor, which is being built to help advance new reactor technologies.
MARVEL will be the first new reactor at Idaho National Laboratory (INL) in more than four decades and is targeting to be operational in 2025.
Testing the PCAT
The primary coolant apparatus test, also known as PCAT, fired up for the first time at Creative Engineers Inc.’s manufacturing facility in New Freedom, Pennsylvania.
The company installed the PCAT back in May and loaded the system with sodium-potassium and lead-bismuth coolants to demonstrate heat removal from its electrically heated core.
DOE is now working toward collecting new data on the system’s temperatures and coolant flow to ensure the MARVEL reactor will perform as expected.
"The MARVEL project underscores the potential of human innovation to address pressing energy security and climate challenges facing modern society," said Yasir Arafat, chief designer and project lead for MARVEL. "This PCAT demonstration is an important step in that process and will help validate and benchmark tools we use to accurately predict how the reactor will perform."
The MARVEL Microreactor
MARVEL is a sodium-potassium-cooled microreactor that is anticipated to generate 85 kilowatts of thermal energy.
It will operate within INL’s Transient Reactor Test Facility and be connected to the lab’s first nuclear microgrid.
MARVEL will be used to test microreactor applications, evaluate systems for remote monitoring, and develop autonomous control technologies.
The reactor could be operational as soon as the end of next year.
What’s Next?
PCAT testing will unfold in phases and initially focuses on demonstrating natural circulation, a critical heat removal mechanism within the system.
DOE is close to finalizing the MARVEL design and is in discussion to procure key long-lead components for fabrication, such as Stirling engines and nuclear fuel.