Testing is underway at an electric-powered microreactor prototype developed by the US Department of Energy (DOE). The 12-foot-tall machine is a full-scale replica of the Department’s Marvel microreactor, which is being built to advance new reactor technologies. Marvel will be the first new reactor at Idaho National Laboratory (INL) in more than four decades and is aiming to be operational in 2025.

The non-nuclear prototype, which weighs 2,000 pounds was completed by Creative Engineers Inc (CEI). The Microreactor Applications Research Validation & Evaluation (Marvel) Project entails the design, development, construction, and start-up of an INL test microreactor, funded by DOE through the Microreactor Programme (MRP). The aim is to establish an operational nuclear applications test bed that can generate combined heat and power to enable integration and R&D with end-user technologies. It will also allow microreactor technologists to test next-generation control systems.

DOE said the primary coolant apparatus test (PCAT) has fired up for the first time at CEI’s manufacturing facility in New Freedom, Pennsylvania. INL built PCAT in 2022, and in May it was loaded onto a truck and transported from INL to CEI’s manufacturing facility in New Freedom, Pennsylvania. CEI installed the PCAT into a two-story frame and loaded it 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. "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." PCAT testing will unfold in phases and initially focuses on demonstrating natural circulation, a critical heat removal mechanism within the system.

The Marvel microreactor is a thermal reactor utilising uranium zirconium hydride (UZrH) fuel with review and authorisation by the DOE Idaho Operations Office (DOE-ID) for National Environmental Policy Act (NEPA) compliance, safety review, and supplemental readiness assessments for start-up and operation. To speed up deployment, Marvel will be established in INL’s Transient Reactor Test (Treat) Facility and will make use of an existing operating Category B reactor facility, approved facility safety basis, operating crews, and recent re-start experience.

The Marvel team consists of INL, Argonne National Laboratory, Los Alamos National Laboratory, Walsh Engineering, Qnergy, Munro & Associates, and CEI. The DOE Microreactor Programme supports research and development of technologies related to the development, demonstration, and deployment of very small, factory-fabricated, transportable reactors to provide power and heat for decentralised generation in civilian, industrial areas.

DOE has conducted an environmental assessment (EA) as part of the NEPA process, which analysed the potential environmental impacts of constructing Marvel inside INL’s Transient Reactor Test Facility. DOE has issued a final EA with a “finding of no significant impact” for the project. A safety design strategy has also been approved by DOE. Marvel is in Final Design Phase, with 90% construction planned complete this year, and fuel load and initial criticality set for 2024.


Image: Testing is underway at the PCAT replica of the Marvel microreactor at Creative Energy's manufacturing facility in Pennsylvania (courtesy of DOE Office of Nuclear Energy)