CFD analysis of the co-axial MYRRHA windowless spallation target design

The MYRRHA project aims for the realisation of an Accelerator Driven System (ADS) demonstration facility for R and D purposes. Among the applications foreseen in MYRRHA are the demonstration of the ADS concept and the demonstration of the performances of ADS for minor actinides transmutation. The MYRRHA spallation neutron source is formed by coupling a high intensity, medium-energy proton beam from a cyclotron to a windowless liquid lead-bismuth spallation target. It is expected that for the 5 mA, 350 MeV proton beam of MYRRHA, 20% of the 1.75 MW beam power will be removed as neutron kinetic energy. The remaining 1.4 MW of beam power is deposited as heat in a zone of approximately 500 cml adjacent to the free surface at a power density of 3.5 kW/cm3. Efficient removal of this heat is a condition for controlling the temperature in the target and poses a major challenge to the thermal-hydraulic design of the MYRRHA target. In order to obtain adequate cooling, the free surface has to be stable and stagnant zones must be avoided. To determine the feasibility of these requirements, an experimental setup was build of the co-axial MYRRHA design. In this experimental setup water and air were used as simulants for lead-bismuth and vacuum. In order to gain more insight in the stability of the free surface and the behaviour of the fluid flow near the free surface, NRG has performed Computational Fluid Dynamics (CFD) analyses. 10 refs