Limets 6: advanced materials research for lead-cooled SMR
The development of EAGLES-300 requires materials that will continue to be reliable under the challenging conditions imposed by liquid lead as a coolant. The high temperature and corrosive environment pose a particular challenge for the material. Only by testing potentially suitable materials (on a long-term basis) in this demanding environment can we chart how they will behave.
That is why the SMR_LFR team has officially started using ‘Limets 6’, an advanced test rig that builds on more than 25 years of experience and is the successor of Limets 1 to Limets 4 inclusive. Designed specifically to characterise material properties such as tensile strength and fracture toughness in an environment of liquid lead (the coolant used in EAGLES-300), the rig helps us chart how different materials behave under these challenging conditions.
How Limets 6 will help us perform more advanced materials research
Limets 6 will enable us to answer crucial questions with regard to reactor design. How does material X, Y or Z behave when subjected to (long-term) loading and exposure in liquid lead at a temperature of 500 °C?
- May we even use the material at all?
- Does it retain its properties as expected?
The results will provide indispensable knowledge that will inform material and design choices and reduce uncertainties during the ongoing development of EAGLES 300.
The test set-up in detail
Test autoclave
Test pieces are placed in the test autoclave, are tightly secured and then heated to 500 °C in the presence of liquid lead. We then perform tensile or fracture toughness tests, in which the material is slowly stretched until it gives way. This allows us to measure the static strength of materials, both with and without pre-applied fissures. By ‘static’ we mean that the load is applied to the material slowly and constantly.
Dump tank
The dump tank collects the liquid lead when the test autoclave is opened. The tank remains continuously heated to 380 °C and is flushed with hydrogen-containing gas to control the oxygen content. By doing this, what we are creating, therefore, is a controlled, corrosive environment that allows us to investigate the behaviour of materials during long-term exposure to liquid lead.
Together, these components are what makes Limets 6 a unique research set-up that is capable of applying forces of up to 50 kN to the various prospective materials.
Looking ahead: Limets 5 coming up
Limets 5 will also follow in late 2025. This installation will focus on dynamically oriented properties, or how materials respond to repeated or sudden loads, such as oscillations or shock. It does this by using a hydraulic piston to alternate the transmission of power. Like Limets 6, this installation closely matches the specific material needs of EAGLES-300.
💡 Did you know that the name LIMETS stands for Liquid Metal Test Station? This is a reference to the unique test environment with liquid lead.
Limets 1, 3 and 4 were specially built to conduct materials research in an environment of heavy liquid metals. Limets 2 was originally developed to test materials in a Pb-Li environment for fusion applications, but was later repurposed to support reactors cooled with lead or lead alloys.
