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Seaborg to collaborate with TU Delft Reactor Institute (NL) on molten fuel salt chemistry  

TU Delft Reactor Institute (the Netherlands) and Seaborg Technologies recently started a one-year project on the investigation of molten fuel salt chemistry for the development of an innovative molten salt nuclear reactor design. The aim of the project is to provide a deeper understanding and modelling of the liquid fuel thermodynamic and physicochemical properties. 


“At TU Delft we are very much looking forward to working together on this promising project. Particularly, we are excited to develop modelling tools that go beyond state-of-the art and can serve the needs of MSR developers”, says Anna Smith, Principal Investigator at TU Delft. 


“At Seaborg we strongly see the academic world as a key player in the deployment of modern nuclear, and we are thrilled to start this collaboration with TU Delft. The results we hope to obtain are 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 support 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. 

Project Approach: Fuel Chemistry

One main challenge for developing of the Seaborg CMSR technology and its commercialisation 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-month Post Doc project, 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 a model is essential for design purposes, for the licensing process, and for 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.  

The Attractive Design of the CMSR 

The CMSR is an advanced, small modular reactor (SMR) with promising inherent 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’s 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 commercialised due to a handful of technical difficulties that Seaborg believes are solved with their patented sodium hydroxide moderator. The choice of liquid moderator allows for a very compact design, 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 it’s delivering process heat for industrial purposes, electricity into the grid of an existing coal port, or power the production of hydrogen and ammonia. 

Read more about Seaborg's technology here.

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.  

Read more about Anna Smith here.

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. 

About Seaborg

Seaborg started in 2014 in Copenhagen with three physicists. Today the company employs around 120 people – from nuclear engineers and chemists to business developers and safety officers. Seaborg owns and operates a couple of laboratories and are well underway to license the next generation of nuclear reactors. 


Seaborg Technologies

TU Delft Reactor Institute


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