Catalyst design is recognized as a part of the integral reactor design at the reactor level. There are several factors that may lead to a reactor surface drop level that creates issues in the long run, like the flood in sensor level, loss or leak of pipeline, feedwater pipe leak, and feedwater supply loss. To understand the failure or what may cause the failure, one should create a reactor surface fault tree analysis diagram. A Fault Tree Analysis (FTA) is a graphical tool to explore the causes of system-level failures. As shown in the attached diagram of reactor surface Fault Tree, it uses boolean logic to combine a series of lower-level events, and it is basically a top-down approach to identify the component-level failures that cause the system level failure to occur.