One-dimensional design approach to integrated steam generator with helical-coil tube bundles for a sodium-cooled fast reactor

Abstract

A potential of a sodium-water reaction in a steam generator (SG) has been known to result in a drastic increase of the capital cost of a sodium-cooled fast reactor (SFR). This is mainly because an essential risk of potential sodium-water reaction (SWR) at the pressure boundary between water/steam and liquid sodium in the SG unit of an SFR. To prevent the SWR event during the whole plant lifetime, the novel design of an integrated steam generator (ISG) concept was proposed and its creative thermal-hydraulic design approach was developed as well. The ISG design for an SFR is based on the concept of combined SG unit with an intermediate heat exchanger (IHX) to make the chance to contact of water vapor with liquid sodium very few. However, it requires far more heat transfer area than that of an existing design with both IHX and SG unit due to the lower thermal conductivity of an alternative intermediate heat transfer medium. In order to minimize the heat transfer area of ISG, its thermal-sizing analyses using three representative design parameters, such as the number of tubes, tube bundle arrangement, and tube inclination angle, were conducted by a one-dimensional analysis code. In this study, the optimal design condition of the integrated steam generator for the reference plant of KALIMER-600 was obtained and the required heat transfer area of the ISG unit was compared to that of the existing SG unit and IHX unit in KALIMER-600. It was found that the proposed ISG design requires 2.25 times of heat transfer area to transport the same amount of heat as the conventional two heat exchanger system.