Transportable Modular Reactor

Image of HolosGen's technology

Manassas Park,
Project Term:
10/01/2018 - 12/31/2021

Critical Need:

Nuclear power provides about one-fifth of U.S. electricity generation, delivering reliable, low-emission, baseload power to the grid. However, the future of nuclear power is unclear; high costs and a rapidly changing grid—including growing renewable resources like wind and solar—present new challenges for existing and new nuclear plants. The next generation of nuclear plants require new technological advances to achieve “walkaway” safe and secure operation, extremely low construction capital costs, and dramatically shorter construction and commissioning times than currently available plants.

Project Innovation + Advantages:

HolosGen is developing a transportable gas-cooled nuclear reactor with load following ability. The reactor concept is essentially a closed-loop jet engine (Brayton cycle) with the typical combustor replaced by a nuclear heat source. The nuclear heat source is comprised of multiple subcritical power modules (SPMs) that only produce power when they are positioned in close proximity, allowing sufficient neutron transfer to reach criticality (steady-state). The modules will be positioned using an exoskeletal structure with fast-actuation technologies currently employed by the aviation industry. By controlling the flow of neutrons across the SPM boundaries, reactor output can be controlled. By using a closed Brayton cycle, a high-power-density engine with components connected directly to the reactor core, plant construction will be simplified and the reactor/generator can be packaged in a standard shipping container. This will make the reactor highly portable, leading to lower costs and shorter commissioning times. HolosGen’s reactor concept will provide low overnight cost, autonomous operations, rapid deployment, independence from environmental extremes, and easy electrical grid connection with near real-time load following capability. Under this MEITNER project, the ARPA-E/HolosGen team aims to demonstrate the viability of this concept using multi-physics modeling and simulation tools, with the thermal hydraulics validated by testing a non-nuclear simulator. The project will improve the understanding of the turbine efficiencies and the coolant flow within the nuclear reactor.

Potential Impact:

If successful, developments from MEITNER projects will inform the development of lower cost, safe, and secure advanced nuclear power plants.


Nuclear power plants contribute to grid stability by providing reliable baseload power.


Nuclear power has low life cycle emissions, making it a key source of clean electricity.


Nuclear power provides high-efficiency electrical generation for the U.S. grid. Reducing plant costs reduces exposure to price volatility.


ARPA-E Program Director:
Dr. Robert Ledoux
Project Contact:
Dr. Claudio Filippone
Press and General Inquiries Email:
Project Contact Email:


Argonne National Laboratory

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