Tenglong Cong

Development and Application of a UTSG Thermal-Hydraulic Analysis Code

Structural integrity of steam generator should be maintained during operation, since it performs as the pressure and heat transfer boundary of primary side coolant. Localized thermal-hydraulic parameters of secondary side are essential for the analysis of tube wastage, fatigue and failure. In this paper, a three-dimensional thermohydraulics analysis code, named STAF, is developed based on FLUENT. With STAF code, three-dimensional thermohydraulics of secondary side of AP1000 steam generator are generated. This code is developed based on the porous media theory. In this code, the drift flux two-phase model coupled with a simplified flow boiling model is utilized to present two-phase flow among the U-tube bundle. Downcomer, tube bundle, support plates and primary separators in steam generator are considered in STAF code. The calculated results are compared with a general steam generator thermohydraulic analysis code ATHOS, which is developed by EPRI steam generator group. The comparison indicates that STAF code performs well in evaluating thermal-hydraulic parameters in steam generator. The results show that the flow field varies significantly at different position in AP1000 steam generator. Flow vapor quality at the inlet of primary separators varies significantly, which is a severe challenge to the capacity design of separators.Copyright

Three-Dimensional Steady Simulation on Two-Phase Flow in Secondary Side of Steam Generator

Steam generator (SG), as the primary-to-secondary heat exchanger and pressure boundary of primary loop, should be integrated and performs well in heat transfer ability. Flow characteristics of the secondary side fluid of SG are essential to analyze U-tube wastage caused by the flow-induced vibration and thermal stress. In this paper, secondary side two-phase flow was simulated based on the porous media model. Additional momentum and energy source terms were appended to the momentum and energy equations of porous media region, respectively. The additional momentum source contained the resistances of downcomer, tube bundle, support plate and separator. The additional energy source included the heat transfer from primary side to secondary side fluid. Solving the control equations by ANSYS FLUENT solver yielded the distributions of velocity, temperature, pressure, density and quality, which can be used in the analysis of flow-induced vibration and separator.Copyright

Transient and Safety Analysis Code for TP-1 Sodium Cooled TWR

As a new concept of reactor, traveling wave reactor (TWR) is under fundamental research. In this paper, we modeled the main parts of primary loop of TP-1 sodium cooled traveling wave reactor, which was designed by TerrraPower Co., and developed a Transient and safety Analysis code for Sodium cooled TWR (TAST) with Fortran program. We first performed a steady analysis based on this code to evaluate the accuracy of this code. The calculated results agreed well with design parameters. After this, this program was used to simulate the loss of flow accident and reactivity insertion accident separately. The transient safety analysis indicated that TWR can work safely under these two accident conditions.Copyright