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The EXOCET facility used to study the performance of the reactor’s passive cooling system as part of the NUWARD™ project​.

Cœur de l’AMR-Na ATRIUM - carré © IRESNE/CEA

EXOCET is part of the POSEIDON platform; it was designed and built by the teams at the Nuclear Technology Department (DTN) with support from the Reactor Studies Department (DER) at IRESNE and the Institute for applied science and simulation for low-carbon energy (ISAS). Like IRESNE, the SAS is an institute at the CEA.
The purpose of tests performed in the EXOCET facility is to map the thermohydraulic conditions that can trigger “chugging”, which is a phenomenon that leads to cyclical flow blockage due to the accumulation of steam.
These instabilities can provoke structural vibration and temperature variations in the walls, particularly in the pipes.

The functional tests performed in 2021 demonstrated the performance of the facility to control the thermohydraulic conditions and accurately detect when natural convection and “chugging” were triggered in the test section simulating the two-phase flow in a component of the reactor’s passive primary cooling system.

The data collected in the EXOCET facility supports the CATHARE-3 modelling of boiling phenomena under natural convection at low pressure, which was carried out by our Reactor Studies Department (DER) and the Department for Modelling Systems and Structures (DM2S) at the ISAS institute.