(A) gas turbine code for off-design performance and transient analysis of high-temperature gas-cooled reactors

Abstract

This study presents the development of dynamic models for a high-temperature gas-cooled reactor (HTGR) through direct coupling of a gas turbine analysis code with a system analysis code. For the off-design analysis, we developed an improved streamline curvature analysis code based on the Newton-Raphson numerical application (SANA), which performs a detailed two-dimensional analysis by means of throughflow calculation incorporated with industry-standard loss correlations for gas turbines. The new numerical method overcomes the weakness of the conventional throughflow calculations such as unstable and gradual convergence resulting in its limited applicability to off-design performance and the transient behavior. To evaluate the steady-state and transient performance of HTGRs, we developed GAMMA-T by implementing the SANA in the transient system code, GAMMA, which is a multidimensional, multicomponent analysis tool for HTGRs. Direct code coupling improves the potential of the scaling and interpolation errors caused by the non-linearity in gas turbine performance maps. In the GAMMA-T, the reactor consists of a one-dimensional thermal-hydraulic model and reactor kinetics models. The heat exchangers and connecting pipes were designed with the one-dimensional thermal-hydraulic model. In addition, the reactivity control and bypass valve control system was modeled for the load transient simulations. We investigated the thermodynamic properties of working fluid in the gas turbine. Design-point and off-design performances were evaluated by applying the SANA code to the GTHTR300 gas turbines. It was found out that the SANA is capable of predicting design-point performance within ±2.5% of deviation compared with the reference design. The off-design performance of compressor showed excellent agreement and the surge margin was also well predicted. The GAMMA-T was assessed by comparing its results with the steady-state of the GTHTR300. The code results were in good agree...