MYRRHA is a flexible fast spectrum research reactor cooled by Lead-Bismuth. Conceived as an Accelerator Driven System prototype, it is able to operate in sub-critical mode. Operating in critical mode, MYRRHA serves as demonstrator for the Lead Cooled Fast Reactor (LFR) which is one of the Generation IV reactor concepts. This kind of nuclear system is highly economical, has enhanced safety, produces minimal waste and is proliferation friendly. In addition, such systems can be used to transmute transuranic elements in shorter-lived waste, thus lowering the burden on deep geological storage.
One of the key components of the reactor is the Primary Heat eXchanger: for improved safety, designers have opted for a double walled PHX, where the gap between the two walls is filled with a fluid that can be coupled to a leak monitoring system.
This solution must be extensively investigated for what concerns its thermal, mechanical properties and behaviour: preparatory tests are foreseen to take place in 2018, while full-scale experiments will be performed as of January 2019.