Échanges par diffusion turbulente entre deux conduits communicants le long d'une génératrice. Cas des réacteurs nucléaires à Grappe

¹ Centre d'Etudes Nucléaires de Grenoble, Service des Transferts thermiques.

Résumé

The design calculations for bunched reactor fuel rod systems require a knowledge of the transfer relationships applicable to the sub-channels between the fuel rods, in which the cooling fluid circulates. The single-phase (liquid) exchanges taking place between two identical adjacent sub-channels are studied experimentally with the aid of a perspex test section, the main points of interest being the effect of intercommunication space and flow velocity on the transfer relationships. A simple local analysis based on the diffusion equation reveals the mixing effects involved and yields an average diffusion coefficient. An interpretation based on the consideration of the average value of each parameter in each sub-channel enables the introduction of this research data into the nuclear reactor design standards, either in the form of a transverse mixing velocity or of a characteristic length coupled, with an average diffusion coefficient. Further research with a single phase is still in progress on the subject of restricted intercommunication spaces, also some research with two-phase flow (water/air).