Assessment of RANS at low Prandtl number and simulation of sodium boiling flows with a CMFD code

Finally, preliminary computations have been carried out in an assembly constituted of 19 pins equipped with a wrapped wire where partial experimental results are available. Computations have shown a pressure drop at the end of the heated length due to the sudden increase of the hydraulic diameter. Thus, the pressure can drop below the vapour pressure leading to liquid vaporization. This first result supports the assumption of boiling in the upper subassembly zone which could possibly lead to a sodium boiling stabilization.