Simulation of Partial and Complete Loss of Flow Accidents for GPWR using ATHLET Code

Abstract

In Nuclear power plants, simulation of the thermal hydraulic systems at loss of flow, accidents is commonly used to perform safety and licensing analyses through regulatory and safety authorities since they are considered as design base accidents. In this paper, a simulation of a thermal-hydraulic model of Germany Pressurized Water Reactor (GPWR) is developed, during loss of flow accident (LOFA) scenarios, such as: trip of one, two, three and four of the Main Coolant Pumps, at operation of 100% reactor power. The developed thermal hydraulic model is formed using ATHLET3.1A code with a point reactor kinetic to predict the behavior of the reactor through the thermal hydraulic major parameters such as power, mass flow rate, primary and secondary pressures, max clad surface and fuel temperatures. All reactivity feedbacks are taken into consideration in the developed simulation and the scram signal of the protection system depends on the mass flow rate. The results show that the investigated ATHLET model can precisely simulate, the steady state and the transient behavior of GPWR during many LOFA accidents. Moreover, the results show that there is good agreement between ATHLET model and RELAP5 code results are nearly in agreement with in previous literatures