MYRRHA is a flexible fast spectrum research reactor under development at SCK·CEN. MYRRHA is conceived as a demonstrator for the Lead Cooled Fast Reactor which is one of the Generation IV reactor concepts. This class of nuclear systems is highly economical, has enhanced safety, produces minimal waste and is proliferation resistant. Furthermore an accelerator driven system like MYRRHA with the core in sub-critical mode can be used to transmute transuranic elements thereby significantly lowering the burden on the deep geological storage. To large extent, these benefits are a consequence of the coolant used in MYRRHA: liquid lead-bismuth eutectic (LBE)
According to previous experience of lead-bismuth cooled systems operation, the coolant chemistry control is the key technology in the development of such systems. Particularly oxygen is the most important chemical element for LBE coolant management, because of its potential contamination of the coolant by forming solid oxide (PbO) and its main influence on the corrosion rate of the structural materials and core internals. The oxygen concentration must be adjusted to a specified value for corrosion control and to avoid production of PbO during service life time. In order to guarantee appropriate oxygen concentration in the entire system, the accurate prediction of oxygen mass transfer is very important. In order to the prediction, accurate measurement of oxygen diffusion coefficient in LBE is needed.