An overview of the thermal-hydraulic code, GINKGO. The assessment of accumulator model

To analyze reactor thermal-hydraulics, many computer codes have been developed. The numerical schemes and capabilities of the computer codes depend on the complexity of physical phenomena, or the applications such as loss of coolant accident (LOCAs) or non-loss of coolant accidents (non-LOCAs). To have self-owned computer codes, China Nuclear Power technology Research Institute (CNPRI) has conducted a series of developments on several computer codes. One of the codes, GINKGO, is a thermal-hydraulic code designed to analyze non-LOCAs of pressurized water reactors (PWRs). GINKGO implements 3-equations with drift model to represent single- and two-phase coolant flows. The slip velocity is credited in the conservation equations to improve the accuracy for two-phase condition. Moreover, several component models are incorporated in Ginkgo in order to simulate multiple coolant loops, reactor safety and control systems, and emergency core coolant systems for PWRs. This paper presents the assessment of GINKGO accelerometer (ACC) model. Two of the LOFT experiments, L1-4 and L3-1, were employed to assess the short-term (∼70s) and long-term (∼2000 s) transient performances of GINKGO ACC model. The assessment results indicate that GINKGO ACC model is adequate to simulate the dynamics of nitrogen expansion during injection process, and provide a certain level of confidence on the GINKGO performance. (author)