The RTS continuously monitors the actual values of neutron flux and other process variables, and it conditions shutdown signals in case these variables reach their setpoints. RTS transmits all vital information necessary for surveillance and monitoring to the control room and other safety and non-safety systems (e.g., initiation status, plant and diagnostic data). RTS can have 3 or 4 redundant channels depending on the design basis of the nuclear reactor, and it can implement a voting logic of two-out-of-three (2oo3) or two-out-of-four (2oo4). Example of 2oo3 configuration is shown in Figure 1. The chassis of the RTS provides external interfaces to power supplies, process I/Os, communication links, local inputs, and indicators.
Figure 1. Reactor Trip System Configuration (2oo3 voting logic version)
A typical RTS (see Figure 2) has on-line monitoring and maintenance capabilities. It can correct its voting logic in case faults are detected, so that system availability is optimized without compromising safety. RTS has a self-diagnostic subsystem, which includes troubleshooting assistance functions for easy localization of faults. In case of failure, RTS puts itself in the safe state, signaling actuation for shutdown. RTS also supports manual actuation of shutdown logic from the Main Control Room (MCR) or Emergency Control Room (ECR). The FPGA-based RTS architecture can be adapted to various reactor types (e.g., PWR, BWR, PHWR).
Figure 2. Reactor Trip System
There are 28 RTSs produced by RPC Radiy in operation at Zaporizhzhe NPP, Rivne NPP, Khmelnitsky NPP and South Ukraine NPP.