Water hammer analysis of valve closure scenarios in the ITER CCWS-1 cooling loop

• CCWS-1 is a closed-loop cooling water system that serves both primary and auxiliary clients within the Tokamak Complex. • Impulse model is developed considering last cooling loop configuration and layout. • Analyses are conducted to characterize the system under water hammer scenarios. • Configurations with different clients’ isolation valves closing time are analysed. The ITER nuclear fusion reactor aims to generate thermal power from the deuterium-tritium fusion reaction burning the confined plasma inside the vacuum vessel. One of the most important aspects of ITER's performance is the effective extraction of heat from plasma-facing components and related systems (such as coils, cryogenic systems, and plasma heating systems). CCWS-1 is a pressurized cooling loop that has the purpose of serving nuclear-relevant clients, such as the Tokamak Cooling Water System (TCWS) and some auxiliary systems, which may contain radioactive inventories. The primary objective of the CCWS-1 is to provide cooling water to clients, keeping thermal-hydraulic parameters such as pressure, temperature, flow rate and water quality within specified ranges. It must perform the safety function of secondary confinement in case of radioactive water leakage. In order to provide support for the CCWS-1 design, a research campaign has been conducted to study the behaviour of the cooling system under water hammer transient conditions. The activity has been conducted using the lumped parameter software AFT Impulse, which performs water hammer transient analyses in complex hydraulic systems. The present paper summarises the modelling methodology and critically discusses the obtained results.