Qualification of the system code CATHARE for nuclear research reactors

Alberto Ghione (1) , François Cochemé (1)

1 STMF - Service de Thermo-hydraulique et de Mécanique des Fluides

In this paper, the recent efforts for the qualification of the thermal-hydraulic system code CATHARE for nuclear research reactors are presented. Even if the code has been extensively validated for commercial pressurized water reactors, additional work was needed due to the unique design and operating conditions of research reactors. In fact, in the core region, the coolant usually flows at low pressures in narrow channels which are arranged in a parallel configuration. Such an arrangement may be subject to the flow excursion instability that can lead to boiling crisis in some of the channels. The study is based on a database of flow excursion experiments in vertical narrow rectangular channels with gap sizes between 1.4 and 3.23 mm. The thermal-hydraulic conditions are representative of the ones in research reactors and the coolant flows either up-or downward. The experimental procedures of these experiments consist in either reducing the mass flux or increasing the heat flux to the channel (keeping all other parameters constant) until the flow excursion occurs. The system code CATHARE is used to simulate the test sections and the experimental procedures are reproduced. The available pressure drops measured over the heated channel are compared to the simulations and good predictions are obtained both in single-and in two-phase conditions. It is also shown that the whole flow excursion phenomenon and, in particular, the mass flux or the heat flux at which the onset of flow excursion instability occurs can be reproduced by CATHARE in a satisfactory way.

Mots clés: NUCLEAR RESEARCH REACTOR; CATHARE; QUALIFICATION; FLOW EXCURSION INSTABILITY

Domaines: Thermique [physics.class-ph]; Mécanique des fluides [physics.class-ph]; Applications [stat.AP]; Energie électrique

Alberto Ghione, François Cochemé. Qualification of the system code CATHARE for nuclear research reactors. 12th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-12), Oct 2018, Qingdao, China. ⟨hal-02124704⟩