A Study on the Field Data Communication Structure under Harsh Environment in Nuclear Power Plants

As digitizing the I and C systems in nuclear plants, The SMART sensors/ actuators are considered as a alternative of the conventional field devices. Because the digitization of the filed level devises is still primitive, it is necessary to perform the relative R and D. Especially, it is difficult to adopt the digital devices in a containment building of the nuclear plants due to the harsh environment conditions such as high level radiation and high temperature. Considering the tendency of the reliability enhancement, from now on, the digital device will be adopted in the harsh environment. The major technical issues of the field level digitization are a SMART transmitter/actuator technology, a network technology and an equipment qualification in harsh environment. This report describes the study results regarding the field level data network. There are many merits such as an automatic test, a diagnostics and auto-calibration when digitizing of the I and C systems. While, the data capacity will be much increased compare to the conventional systems. The future field data network should have larger data transmission speed compare to the current sensor networks such as HART and deviceNET. The candidate commercial network has been selected considering the nuclear requirements. Based on the this network, a protocol structure and a access control structure are recommended. Instruments in containment building are analyzed and the design bases and requirements have been setup to assure the safety and performance of the field data communication. According to the design bases, requirements and the node allocation criteria, the field network has been divided by functional segmentation and each instrument has been allocated to each individual data network