Simulation of the depressurisation occurring at the beginning of a LOCA in a 4-loop PWR

The safety analysis of Pressurised Water Reactors (PWR) is based on the assessment of the consequences of a hypothetical Loss of Coolant Accident (LOCA). The accident supposes that a break occurs on a pipe of the primary circuit. A depressurisation wave propagates from the break through the entire primary circuit, then the circuit empties progressively in diphasic regime. This study focuses on the phase of depressurisation happening during the first milliseconds following the break opening. The geometry of the primary circuit is simplified and represented with a pipe-model to be able to simulate the accident in the entire circuit. The reactor is supposed to work in operating conditions when the accident takes place. After a brief presentation of the geometry and the numerical model, the hydraulic consequences of the LOCA are analysed.