The design of various systems and equipment of a plant should ensure their robust performance under steady-state as well as transient conditions. The various plant states as defined in International Atomic Energy Agency (IAEA) [14.1] are presented in Table 14.1. The steady-state conditions are selected focusing mainly on the optimum performance of the plant. The transient conditions are identified to ensure plant safety as well as component safety. Plant dynamic analyses are performed to demonstrate safety. Important aspects that would emerge from the analysis are (1) method of prevention and mitigation, (2) response time, (3) reliability, and (4) functional performance. Various operating parameters and procedures for the plant are also worked out based on dynamic analysis. All these targets can be achieved only through dynamic simulation of the entire plant. The degree interdependence of various systems and components in achieving the ultimate design objectives can also be assessed only through such simulations.