Development of the plant dynamics analysis code NETFLOW plus

The present paper describes the one-dimensional thermal-hydraulic network code NETFLOW++ which can simulate the plant transients of various types of nuclear reactors and facilities consisting of various components like pumps, valves, and heat exchangers connected by piping. Numerical proportional-integral-derivative (PID) control systems are also incorporated to control velocity of pumps, throttling of valves, vanes for an air cooler, etc. The newly developed code consists of the NETFLOW code which can simulate the nuclear steam supply system and the PLUS code which can simulate the turbine and the feed-water system. Thermal-hydraulics and neutronics of the coupled system of the core, heat transport systems and the turbine system can be calculated by this code. Moreover. the code can simulate various fluids such as water, heavy water, liquid sodium, lead and lead-bismuth in the heat transport systems. The main point of this paper is a description of the basic equations used in this code for the liquid metal cooled reactor. A steady state of the liquid metal cooled reactor is calculated using a full model of the code to check the capability of the models incorporated into the code. Then, the turbine trip transient conducted at the 'Monju' reactor was calculated with the same model. Good agreement was obtained in steady state and transient state between the test and the calculation. However, the calculation of the turbine system in the steady state was sensitive due to phase change of extracted vapor and drain water from single-phase to two-phase and vice versa. (C) 2009 Elsevier B.V. All rights reserved.