Thermal hydraulics analysis of once-through steam generator

A steam generator used in the nuclear power plant is the key component to connect the primary loop to the secondary loop. The concept of the once-through steam generator (OTSG) is developed for the integrated advanced nuclear reactor because superheated steam is generated by it and thus the moisture separator is not necessary. The structure of the nuclear reactor would become compact and the reactor safety would also be improved. The OTSG mounted vertically inside the reactor pressure vessel is a countercurrent heat exchanger consisting of annulsar tubes heated bilaterally. We established the homogeneous one-dimensional flow model for analyzing the thermal hydraulic characteristics of the OTSG during the steady and transient states. For obtaining the thermal hydraulics parameters of OTSG appropriate heat transfer and friction coefficients empirical correlation equations in the different heat transfer regimes are utilized. The enthalpy and temperature profiles of the primary and secondary coolants in the steady and transients states are calculated using the simulating code developed by the model. Other important values such as wall temperatures of the inner and outer tubes are also obtained. The important issues related to the structure design and safety of the OTSG are also discussed. (authors)