Flow and temperature distribution evaluation on sodium heated large-sized straight double-wall-tube steam generator

Kisohara, Naoyuki ; Moribe, Takeshi; Sakai, Takaaki

The sodium heated steam generator (SG) of the commercialized FBR being designed in the Feasibility Study is a straight double-wall-tube type and it is large-sized to reduce the manufacturing cost by economics of scale. This paper addresses the temperature and flow multi-dimensional distributions at steady state to obtain the prospect of the SG. Large-sized heat exchanger components are prone to have non-uniform flow and temperature distributions. These phenomena might lead to tube buckling or tube to tube-sheet junction failure in straight tube type SGs. The flow adjustment devices installed in the SG are optimized to prevent these issues, and the temperature distribution properties are uncovered by analysis methods. The analysis model of the SG consists of two parts, a sodium inlet distribution plenum (the plenum) and a heat transfer tubes bundle region (the bundle). The flow and temperature distributions in the plenum and the bundle are evaluated by the three-dimensional flow code "FLUENT" and the two dimensional thermal-hydraulic code "MSG". The MSG code is particularly developed for sodium heated SGs in JAEA. These codes have revealed that the sodium flow is distributed uniformly by the flow adjustment devices, and that the lateral tube temperature distributions remain within the allowable temperature range for the structural integrity of the tubes and the tube to tube-sheet junction.