Background
Microreactors have revolutionary potential to open a range of new applications such as microchip manufacturing, petrochemical production, healthcare, desalination, hydrogen production, data centers and beyond.
Microreactors are compact nuclear reactors defined by their ability to be built in a factory and transported by truck, rail or plane, and are self-adjusting. Due to their small size, microreactors are uniquely suited to service nontraditional energy markets such as off-grid communities, remote locations, military bases, and disaster relief missions. These markets currently face economic and energy security challenges that can be uniquely addressed by this new class of innovative nuclear reactors.
Program Overview
The Microreactor Application Research Validation and Evaluation (MARVEL) is a sodium-potassium-cooled microreactor that is being developed by the U.S. Department of Energy. It will generate 85 kilowatts of thermal energy and approximately 10 kilowatts of electricity. It will be located at the Transient Reactor Test Facility at Idaho National Laboratory.
The MARVEL microreactor is expected to serve as a nuclear test bed to demonstrate microreactor operations and end-use applications, paving the way for unleashing private sector innovation in nuclear energy technology.
Operation of MARVEL will result in lessons learned for commercial developers and will also create momentum, champion rapid technology maturation, and engage microreactor end-user companies directly.
MARVEL directly supports the Trump Administration’s goal of expanding nuclear energy production by accelerating the testing of microreactor technologies for eventual deployment and commercialization.
Current Opportunities
MARVEL Expression of Interest
DOE is currently seeking an Expression of Interest (EOI) from industry providers to suggest potential tests and experiments that leverage the MARVEL microreactor.
The goal of this effort is to provide a platform where the private sector can gain access to an operational microreactor to demonstrate innovative new use cases for microreactors.
MARVEL can be used for a wide range of applications including, but not limited to, novel nuclear-generated heat or electricity applications, novel safeguards, advanced controls, and data validation.
Promising concepts submitted through the initial EOI will be invited to respond to a potential notice of opportunity at a later stage. The EOI will close at 5 p.m. EST on August 30, 2025.
For more information on the MARVEL EOI, please visit SAM.gov or REGISTER for DOE's upcoming webinar on July 14, 2025.
Announcements
- Fuel Fabrication Starts for MARVEL Microreactor (February 2024)
- TRIGA International to Supply Fuel for MARVEL Microreactor (December 2023)
- MARVEL Microreactor Reaches Final Design Step (October 2023)
- MARVEL Prototype Starts Testing (September 2023)
- Idaho National Laboratory Builds Full-Scale Prototype for Microreactor Project (February 2022)
- MARVEL Environmental Assessment (November 2021)
- MARVEL Final Environmental Assessment (June 2021)
- New MARVEL Project Aims to Supercharge Microreactor Deployment (April 2021)
What is MARVEL and why is it important?
MARVEL is a sodium potassium-cooled microreactor that uses uranium zirconium hydride fuel, a version of TRIGA fuel that is similar to what is used in university research reactors across the country. The microreactor will employ natural circulation cooling and operate at a temperature range of 500-550°C. Process heat applications can expect to receive an inlet fluid temperature upwards of 300°C. MARVEL is capable of producing 85 kilowatts of thermal energy and approximately 10 kW of electricity.
MARVEL is a first-of-a-kind microreactor test bed intended to pioneer the integration of nuclear generated power into non-traditional applications.
What can MARVEL be used to power?
MARVEL can be used to power a wide range of different applications. Example applications for electricity use-cases include powering a microgrid, small data center node, or charging station. Example heat use-cases could be synfuel production, chemical processing, or novel heat application.
How small is MARVEL?
MARVEL is approximately the size of a sedan car. The reactor is around 15 feet tall and will be housed in the TREAT underground pit.
Where will MARVEL be located?
The reactor is slated to be installed at the Transient Reactor Test (TREAT) facility located at Idaho National Laboratory. TREAT is within the Materials and Fuels Complex (MFC) at the INL site.
What is the current deployment timeline for MARVEL?
Key components of MARVEL are already under fabrication with several systems (e.g., guard vessel) already completed and in storage. Assembly for the reactor is expected to complete in 2026 with installation in TREAT starting in late 2026. Dry initial criticality is anticipated to occur in 2027 with transition to full power operations in 2028. The first stage of operation will consist of electricity generation with the second stage, likely in 2029, transitioning to process heat generation.
How long will MARVEL operate?
MARVEL is currently expected to be in operation for two years from 2028 to 2030. An experiment testing plan will be released at the conclusion of the EOI and notice of opportunity process to determine the sequence of demonstrations during the operational timeline. The reactor is currently anticipated to operate primarily during “off-shifts” at the TREAT facility when the other TREAT reactor is not operational. This typically extends from Friday through Sunday. However, depending on needs, continuous week-long operations can be accommodated.
How is MARVEL funded?
MARVEL is funded under the U.S. Department of Energy, Office of Nuclear Energy, Microreactor Program within the Advanced Reactor Technologies Program.
Could MARVEL one day be commercially deployed?
The MARVEL design itself is not intended to be a commercial product. However, the project is keen to work with stakeholders on commercialization of different aspects of the technology and supporting the maturation of novel concepts being pursued by industry.
How does DOE define “novel” applications? What does this mean?
Novel applications consist of use cases that have never been previously demonstrated with a nuclear reactor or proven applications with limited data. For instance, nuclear energy has never been previously shown to power a data center directly, or to provide heat for chemical processes. Preference will be given to applications that have never been previously coupled to a nuclear reactor, but applications that have seen limited demonstration time but lack data are also encouraged.
Potential use cases that are eligible include connecting an electrical application to the reactor, connecting a thermal storage system to the process heat system, coupling the process heat system to a chemical process, conducting a specific transient within the allowed safety basis with the reactor, or demonstrating novel controls paradigm.
What are examples of applications that are not eligible for the EOI?
Any application that requires drastic changes to the reactor, which is already under fabrication, or the safety basis will not be considered. Examples include fitting a sensor that will require a modification to the reactor vessel, inserting novel fuel or material inside the core, or drastically altering the balance-of-plant.
Who is eligible to apply?
Responses must be led by the private sector and be a U.S. based company. Preference will be given to end users of nuclear energy. Specifically, interested parties who can leverage the energy produced by a reactor. University or national labs can be listed as supporting entities.
Do interested parties need to reply to the EOI to be eligible for the subsequent notice of opportunity?
Failure to respond to the EOI will not disqualify eligibility to the subsequent notice of opportunity, however respondents to the EOI will be favored.
When will the MARVEL notice of opportunity be issued?
The notice of opportunity is expected to be issued in calendar year 2026, following the review of EOI submissions. It will be made publicly available on SAM.gov.
Does DOE anticipate any funding tied to the notice of opportunity?
While there are no direct financial awards related to the anticipated notice of opportunity, funding is expected to be provided in the form of a cost-share with the end user. The majority of funds provided by DOE will be leveraged to cover national laboratory staff hours in support of the end user application.
If there is no direct financial award tied to the future notice of opportunity, why should industry be interested? What is the benefit of participating in a self-funded MARVEL application test case?
Stakeholders who are self-funded can greatly benefit from the demonstration of novel nuclear applications that can be commercialized in the future. Tests conducted with MARVEL can result in substantial experimental data that can prove to be invaluable for scale-up commercial demonstrations in the future. Applications can significantly de-risk novel technologies and help secure follow-on funding in the future.
Furthermore, proprietary intellectual property (IP) generated as part of these demonstrations can be protected subject to contractual agreements between the different stakeholders.
What are the anticipated steps toward ultimate demonstration of a novel MARVEL application?
Following the response to the EOI and to the subsequent notice of opportunity, successful end users will conduct a feasibility assessment of their proposed application in collaboration with a DOE national laboratory. This will then form the basis for any follow-up notice of opportunity to then deploy the physical demonstration within the 2027 to 2030 timeline.