Development of a hot cell test set-up for liquid metal embrittlement (LME) studies in lead-lithium and lead-bismuth

Liquid Metal Embrittlement (LME) is defined as the brittle fracture (loss of ductility) of usually ductile materials in the presence of a liquid metal. The sensitivity to LME is likely to increase with irradiation hardening as localised stresses can promote the aggressive action of a liquid metal. To investigate the mechanical response of irradiated materials in contact with a liquid metal, an instrumented hot cell is being developed. The testing machine installed inside will allow mechanical testing of active materials in liquid lead lithium and liquid lead bismuth under well controlled chemistry conditions. Typical mechanical tests that can be carried out are SSRT, constant load and rising load tests at temperatures from 150°C to 500°C. A special requirement of the hot cell set-up is that the irradiated samples can be retrieved from an irradiation rig without any supplementary damage. Therefore a dedicated dismantling set-up has been designed as well. The LME test set-up will consist of three vessels; besides the autoclave and loading unit two more vessels are used to prepare a test. The first vessel (melting tank) is only used to melt the lead mixture for the first time. Impurities and the always present oxide layer on top of the liquid metal can be removed. The second vessel (dump tank) is used to condition the liquid metal with a gas, for example hydrogen. After the conditioning, the liquid metal mixture is ready to be used for testing. Part of this set-up consists of a vacuum pump and an argon gas supply, which are used to prevent the contact of liquid metal with air and humidity. Tensile tests can be performed with a loading unit allowing strain rates in the range of 10-3 to 10-7 s-1 with a maximum load of 20 kN In this presentation we will focus on the technical design of the test set-up and the special features that have been developed to allow testing in a hot cell environment.