It is shown how to use the GO-FLOW methodology in "Risk Monitor" system. Operator, faced to risk monitor, gives plant conditions and obtains present plant risk state, interactively. For this purpose, the GO-FLOW analysis can be performed flexibly correspond to the change of plant configuration and required mission. The GO-FLOW framework can automatically give graphical style of analysis results. It corresponds to a display window of risk monitor system, which visualizes risk state intuitively. In this study, take up a BWR nuclear power plant and consider a hypothetical sequence of accident conditions based on the Fukushima Daiichi accident. The applicability of GO-FLOW to risk monitor system has been shown.