Evaluation on the size of steam generator of Pb-Bi cooled FBR (1); Analyses by one dimension steady thermal-hydraulic calculation code

not registered ; not registered  ; Soman, Yoshindo

Compared to a sodium cooled FBR, the cost ratio of a steam generator(SG) to the total cost of Pb-Bi cooled FBR plant is relatively high, because the main piping, pumps and IHXs are eliminated in the natural circulation Pb-Bi FBR. Then, reducing the size of the SG has a greatly influence on the total construction cost in Pb-Bi cooled FBR. In this study, the size of the SG of the natural circulation Pb-Bi cooled FBR was evaluated by using one dimensional steady thermal-hydraulic calculation code (POPAI-6) to obtain more benefit of the plant construction cost. Raising Pb-Bi temperature and adopting heat transfer promoting tubes (which provide grooves inside) to the SG are considered to be the effective method of reducing the heat transfer area. However, another study revealed that Pb-Bi is inferior to sodium in the wetting to the tube surface and this property leads to the less thermal convection. Thus computer code POPAI-6 indicated these effect on the heat transfer area of the SG. Raising Pb-Bi temperature and adopting heat transfer promoting tubes achieve a 23% and 15% decrease of heat transfer area respectively. And both methods enable to diminish 34% of the heat transfer area. However, the less wetting of Pb-Bi to the tubes surface considered, the heat transfer area was estimated to increase by 14%. This effect must be considered in designing the SG and Plant system.