Enabling Load Following Capability in the Transatomic Power MSR

Project Term:
06/28/2018 - 09/30/2021

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:

The University of Illinois, Urbana-Champaign (UIUC) will develop a fuel processing system that enables load-following in molten salt reactors (MSRs), an important ability that allows nuclear power plants to ramp electricity production up or down to meet changing electricity demand. Nuclear reactions in MSRs produce unwanted byproducts (such as xenon and krypton) that can adversely affect power production. In steady, baseload operation, these byproducts form and decay at the same rate. When electricity production is ramped down, however, the byproducts start to be produced at a greater rate than they decay, leading to a buildup within the reactor. When power production must be once again increased, the response rate is slowed by the time needed for the byproducts to reach their equilibrium level (determined by the radioactive decay half-life, which is on the order of hours). Thus, buildup of these unwanted byproducts resulting from ramping down inhibit proper load following for molten salt reactors. Fortunately, MSRs transport fuel in a flowing molten salt fuel loop, which means that a section of the reactor, outside the core, can be leveraged for fuel processing and “cleanup.” The team will determine the feasibility of removal of these unwanted byproducts and design a fuel reprocessing system, removing a major barrier to commercialization for molten salt reactors.

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 lifecycle 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. Caleb Brooks
Press and General Inquiries Email:
Project Contact Email:

Related Projects

Release Date: