RELAP5 (Reactor Excursion and Leak Analysis Program) is the most widely used Nuclear Power Plant (NPP) system code for thermal and hydraulic analysis of Light Water Reactors (LWRs). The version RELAP/SCDAP with extended part on Severe Core Damage Analysis Program (SCDAP) developed by Innovative Systems Software (ISS) is used in more than 30 countries in the world for the design and safety analysis of power and research reactors, advanced fluid systems, and experiments. The capabilities and salient features of the software include: (a) it is a state-of-the-art tool to simulate wide range of design basis and severe accidents (b) its point reactor kinetic model enables coupled behavior of the reactor coolant system and reactor core during severe accidents as well as large and small break loss-of-coolant accidents, and (c) it offers the capability of addition of new coolants for advanced reactor and fluid systems by implementing fluid properties and correlations in the code. The course will focus on: