Applying Engineering Simulator to Verification and Validation of Digital I&C in Nuclear Power Plant

In China, more and more Nuclear Power Plant (NPP) will be constructed in the near future years, and Main Control Room (MCR) will introduce digital Instrumentation and Controls systems (I&C) technique. I&C system of nuclear power plant consists of Control Systems, Reactor Protection System and Engineered Safety Feature (ESF) Actuation System. For example, I&C system of LinAo Phase II NPP has adopted SIEMENS TXP and TXS I&C, which is being constructed in Guangdong province, China. In this engineering project, Chinese engineers are responsible for all the configuration of actual analog and logic diagram. Before the phase of real plant testing on the reactor, engineers want to make sure that configuration is right and control functions can be accomplished, so primary Verification and Validation (V&V) of I&C works were done. One way is checking the diagram configuration one by one according to the original design. There are two main disadvantages. One is diagram is so complex that workload is very large and engineers will make mistake. Another is even engineers have read every logic, but they still cannot know the final results and function of a complex control system. So another effective V&V way is applying NPP engineering simulator to do virtual test. According to LinAo Phase II NPP design, we develop one simulator to construct a virtual NPP model as a basis, which can provide plant operation parameters and can also accept control signal from I&C, then give response to it. Through this way, we don’t need to know the exact diagram, and just observe input and output of I&C to make sure that the final results is right and functions have been accomplished. In this way, it is need to transfer signals between simulator and I&C. For keeping the original software and hardware structures of SIEMENS Distributed Control System (DCS), we use one set of data acquisition (DAQ) equipments to build a connection between the engineering simulator (software) and SIEMENS DCS I/O cabinet (hardware), and the interface is standard 4–20mA direct current and 0–48V direct voltage. This way is convenient for expansion to other digital I&C V&V. After these two V&V works, we can then build the confidence of digital I&C control function. As an application research, we mainly focus on V&V of digitalized control systems and selected several Reactor Control (RRC) systems as examples, including pressurizer pressure and water level control, steam generator water level control. In this paper, we will introduce the way of applying engineering simulator to do V&V works, the structure of our simulator, the function of different block, and primary V&V results. Moreover, we will have ideas on the future application of this methodology to V&V of Reactor Protection System and ESF Actuation System.