Analysis of the Alarm Generation and Display for the Reactor Accidents in HTR-PM

Nuclear safety is one of the key issues for a nuclear power plant (NPP). The alarm system plays a critical role for the safe and efficient operation of an NPP which affects the correctness and efficiency of the operators in dealing with the accidents. It is even more important for the alarm system of a multi-modular NPP which has more than one reactor modules in a single unit because all the modules are usually monitored in the same main control room. The alarm generation and display mechanism of a typical multi-modular NPP, the High Temperature Gas-Cooled Reactor - Pebble bed Module (HTR-PM), is analyzed in this paper which has two reactor modules coupled to one steam turbine. Three operators are responsible for the operation of two nuclear islands and a conventional island, respectively. The alarm generation and display processes will be discussed in this paper. Firstly, the architecture of the RPS and the alarm system related to the red and yellow alarms is introduced. Then the generation and display mechanism of the red and yellow alarms is proposed. A protection variable of a design basis accident is given as an example for the alarm signal handling. The characteristics of the alarm system are then discussed. More optimization directions on the alarm design for multi-modular NPPs are proposed in the end.