Fossil free fuels for floating power plants

News - 22 November 2022 - Communication TNW

TU Delft, the Netherlands and Seaborg Technologies, Denmark, started a one year project on the investigation of fuel molten salt chemistry for the development of an innovative molten salt nuclear reactor design. The researchers at TU Delft are Dr Anna Smith (Associate Professor) and Lukasz Ruszczynski (Postdoc). Seaborg Technologies’ vision is to deliver clean, cost-competitive, and safe energy with their promising Compact Molten Salt Reactor (CMSR) concept.

Attractive design
The CMSR is an advanced, small modular reactor (SMR) with promising inherently safety characteristics. The CMSR uses molten fluoride salt both as uranium fuel carrier and coolant. Uranium is an integral part of the fluoride salt composition and is circulated in the molten salt matrix in and out of the reactor core. In the CMSR, the fuel salt enters the core at around 600°C, where it is circulated in proximity of Seaborg patented, molten sodium hydroxide moderator technology, enabling fission. The fuel salt reaches 700°C at the reactor core exit and transfers energy in the form of heat via a heat exchanger to an additional non-radioactive loop of molten salt that heats water to eventually deliver steam. 

The molten salt reactor technology was originally developed in the US in the 1950’s and 1960’s but it was never commercialized due to a handful of technical difficulties, that Seaborg believes are solved with their patented sodium hydroxide moderator. The choice of liquid moderator results in a very compact design, which is advantageous for the maritime deployment Seaborg is seeking: a floating power plant, the CMSR Power Barge. 

A floating power plant
The CMSR Power Barge comes as a turn-key product, assembled and commissioned at the shipyard, and ready to be moored at an industrial harbour. Seaborg has partnered with Samsung Heavy Industries to achieve high volumes of production for their power barge.

The Power Barge design is modular and delivers from 200 to 800 MW-electric for a 24-year lifetime. The CMSR Power Barge is designed to be cost-competitive, whether to deliver process heat for industrial purposes, plug into the grid of an existing coal port, or power the production of hydrogen and ammonia.

Seaborg, The Reactor

Project approach: fuel chemistry
One main challenge for the development of the CMSR technology and its commercialisation in the near future is a thorough understanding and modelling of the liquid fuel thermodynamic and physicochemical properties, i.e., solidification temperature, density, viscosity, heat capacity, thermal conductivity, and vapour pressure. The reference fuel salt for the CMSR design of Seaborg is a fluoride NaF-KF-UF4 eutectic mixture. However, the data available on this system are very limited to this date, and a comprehensive thermodynamic assessment is missing.

In this 12 months Post Doc project of Lukasz Ruszczynski, the focus will be on the development of a coupled model of the structural and thermodynamic properties of the salt system from a microscopic to a macroscopic scale, combining experimental measurements, atomistic simulations, and a thermodynamic modelling approach. 

Such model is essential for design purposes, for the licensing process, and safety assessment of the fuel performance during reactor operation and accidental conditions. The multi-scale modelling approach itself goes beyond the state-of-the-art of traditional modelling tools, focusing on the structure-property relationships. The intention is to provide better predictive capabilities of fuel performance compared to the current methods. 

About the cooperation Seaborg-TU Delft
 “As TU Delft we are very much looking forward to working together for the development of this promising project the Compact Molten Salt Reactor (CMSR), and are excited to work on the development of modelling tools that go beyond the state-of-the art and can serve the needs of MSR developers”, says Anna Smith, Principal investigator at TU Delft.

“At Seaborg we strongly believe the academic world is a key player in the deployment of modern nuclear, and we are thus thrilled to start this collaboration with Anna Smith and TU Delft. The importance of the results we hope to obtain in this project is two-fold. We want to pave the way for more advanced modelling of fission products in the fuel salt, and we want publication of peer-reviewed data to signal the need for transparent and open cooperation between developers across public and private sectors”, says Luca Silvioli, Chemical Process R&D Team Lead at Seaborg.

About Seaborg
Seaborg started in 2014 in Copenhagen with three physicists. Today they employ around 120 people – from nuclear engineers to business developers. They own and operate a couple of laboratories and are well underway to license the next generation of nuclear reactors.

Seaborg, The Reactor

About Anna Smith
As an associate professor at TU Delft, Anna Smith specializes in nuclear materials chemistry including fuel and fission products, and their interaction with cladding and coolant, both for current and next generation (Generation IV) nuclear reactors. In the project with Seaborg, she will supervise the Post Doc working on the unravelling of the thermochemical and thermophysical properties of the molten fuel salt and the relationship between structural and macroscopic properties. 

TU Delft, Radiation Science & Technology, Anna smith

About TU Delft Reactor Institute (RID) and department of Radiation, Science & Technology (RST) 
For more than 50 years, the TU Delft Reactor Institute and the scientific department RST have formed the Dutch knowledge centre for research and education in the field of radiation and nuclear techniques. With our knowledge and expertise, we make an important contribution to fundamental and applied scientific research, using neutrons, positrons, electrons, protons, gamma radiation or radioisotopes. A large part of the research focuses on medical applications, such as the production of medical isotopes and the detection, diagnosis, and treatment of cancer. In addition, new materials are developed for sustainable energy such as solar cells, batteries and efficient cooling/heating, and research is carried out into clean and safe nuclear energy.

More information
Seaborg, Mikkel Veje Rønsbo, Media and Public Affairs Specialist

TU Delft Reactor Institute Femke Werkman, Advisor Communication
M +31 (0)6 43287791