Engineers at Cambridge Atomworks have started experimental testing on the ODIN micro-reactor at a new site in Granta Park, Cambridge. The facility contains a dedicated high-bay workspace and chemical laboratories. The team will use these areas to build large non-nuclear test rigs and study the primary engineering systems of the reactor.
The ODIN reactor relies on specific mechanical and physical principles to remain compact and transportable. The system uses a liquid salt coolant rather than pressurized water. Liquid salt can absorb high levels of thermal energy while remaining at low operating pressures.
“The high fidelity required in the safety qualification of pressure vessels in more conventional water-based reactor concepts is a large safety and cost concern,” explained Cambridge Atomworks.
In contrast, low-pressure salt systems remove the need for such heavy containment structures. Inside the reactor core, the design places the nuclear fuel and the neutron moderator together in the same physical unit. This co-located layout uses internal space efficiently and reduces the overall volume of the core.
Testing the core concepts
The approach draws on a fuel concept first developed by General Atomics during the 1950s Atoms for Peace initiative. That fuel system was later deployed to research reactors across more than thirty nations.
Safety systems on the micro-reactor use ambient air as the final heat sink instead of large bodies of water. Because the plant does not need a nearby river or lake, operators can place it in remote or dry regions.
If power stops, natural convection continues to move the molten salt through the internal circuits. At the same time, the reactor auxiliary air cooling system relies on natural air circulation to carry residual heat away from the vessel walls.
To test these core concepts, researchers at Granta Park are studying the thermal and chemical properties of the coolant. The laboratory uses an STA-MS system to gather data on the salt.
“These properties, relating to fuel performance, are being characterised utilising a state-of-the-art STA-MS system which enables simultaneous thermogravimetric, heat flow, and mass spectrometry analysis,” noted the company in a press release.
Physical test rigs to study fluid movement
The team has also set up physical test rigs to study fluid movement and heat dissipation under realistic conditions. Engineers have assembled a prototype air-cooling rig to test the passive safety systems.
Data from these non-nuclear trials provides baseline measurements to check the accuracy of digital computer models. The team will soon add a corrosion rig to test candidate alloys against hot fluids over time. These tests will help engineers select verified materials for the reactor vessel before testing operational control systems.
“It will allow us the space and height to build our demonstrator rigs and the chemistry facility will give us the analytical platform to investigate the chemical processes inherent in our reactor system, which will accelerate the completion of the ODIN design,” concluded Ian Farnan, CEO at Cambridge Atomworks.