British engineering firm Cambridge Atomworks has launched experimental testing for its ODIN nuclear microreactor at a new facility in Granta Park, Cambridge.
Engineers at the site are assembling large non-nuclear test rigs to evaluate cooling, heat dissipation and advanced materials for the prospective reactor before any nuclear material is introduced.
Liquid salt cooling and reactor size
A central feature of the ODIN design is the use of liquid salt as a coolant instead of water. Molten salts transfer large quantities of heat at relatively low operating pressures, allowing developers to eliminate heavy high-pressure equipment, decrease overall structural mass and build a more compact, transportable reactor.
To reduce core dimensions further, the reactor layout integrates nuclear fuel and a neutron moderator into a single structural component. The fuel concept relies on designs originally created by American company General Atomics during the U.S. Atoms for Peace initiative in the 1950s, which were later adapted for research reactors worldwide.
Microreactors are small, factory-assembled nuclear power units designed to supply portable electricity and heat to remote communities, industrial sites and off-grid locations. Granta Park, located near Cambridge, is a major science and technology cluster housing research laboratories. Unlike conventional light-water reactors that require massive high-pressure containment vessels, molten salt systems operate safely near atmospheric pressure, significantly simplifying transportation and construction logistics.
Passive safety and air cooling systems
The design prioritises passive safety mechanisms so that heat removal does not depend on continuous electrical power or active pumps. If power supply fails, the liquid salt coolant is engineered to maintain circulation through natural convection alone.
The reactor relies on surrounding air as its ultimate heat sink. An auxiliary cooling system uses natural air circulation around the reactor vessel, eliminating the need for proximity to rivers, lakes or major water sources and enabling deployment in arid or isolated areas.
Engineers at Granta Park have constructed a prototype air-cooling system to verify passive heat removal performance. At the same time, researchers are analyzing the chemical and thermophysical properties of the salt coolant using a specialized laboratory installation that simultaneously measures sample mass changes, thermal behavior and the chemical composition of released gases.
Corrosion testing and future development
The next phase of testing involves building a dedicated corrosion test rig where candidate metal alloys will undergo long-term exposure to hot working fluids to identify suitable materials for the reactor vessel and internal systems.
Data gathered from physical experiments will be used to calibrate and refine computer simulation models of the ODIN system. Following validation of the models, developers plan to progress to testing control systems.
The current program consists entirely of non-nuclear engineering trials intended to validate structural principles and finalize the ODIN design, according to report details published by Interesting Engineering, before any nuclear reactor startup takes place.
