A Computational Fluid Dynamics (CFD) simulation of 19-pin fuel bundle has been performed in Ansys Fluent 17.0 to develop a post-blowdown modeling of Indian Pressurized Heavy Water Reactor (IPHWR) fuel bundle for the case of a large break loss of coolant accident (LBLOCA). Simulation has been performed at high temperature and at low steam flow rate with different decay power of fuel rod. This resembled the case of a severe accident such as loss of coolant accident (LOCA) with the failure of emergency core cooling system (ECCS). The results are presented for the temperature of pressure tube (PT), steam and fuel elements of different ring along the test section at different decay power (0.5%, 1%, 2% and 5%).