Velocity field and flow redistribution in a ballooned 7x7 fuel bundle measured by magnetic resonance velocimetry - Université de Lorraine Accéder directement au contenu
Article Dans Une Revue Nuclear Engineering and Design Année : 2020

Velocity field and flow redistribution in a ballooned 7x7 fuel bundle measured by magnetic resonance velocimetry

Résumé

During a loss of coolant accident (LOCA), blocked sub-channels may appear due to the swelling of the fuel rods' cladding, which results in ow redistribution during the reflooding phase. For this reason, special attention has been paid to the effect of fuel rods ballooning on the thermal-hydraulics in LOCA conditions. Due to the practically impossible physical or optical access to blocked sub-channels, no experiment so far has performed precise three-component velocity field measurements in the presence of ballooned regions. In this study, we used magnetic resonance velocimetry (MRV) to obtain three-component velocity fields of water ow within two 7x7 fuel rods bundles built mainly in plastic, one regular and one containing sixteen ballooned fuel rods with 90% blockage ratio and 240 mm blockage length. We present herein results with 50 lpm water ow rate. With the regular bundle, the performance of spacer grids' mixing vanes to homogenize the flow was notable. With the ballooned bundle, we observed transverse velocities upstream of the ballooned zone that are as intense as the bulk mean velocity. Furthermore, there are substantial decreases in the axial velocity within blocked sub-channels up- and downstream of the ballooned zone, reaching near-zero and even negative values downstream, indicating ow recirculation. Although the flow is highly affected by the ballooned zone, the mixing spacer grid placed downstream remarkably homogenized the flow and effects of the flow redistribution disappeared. Finally, with the present ballooned bundle configuration, about 90% of the flow that should pass through blocked sub-channel deviates towards less resistant regions, which suggests a predominant geometric effect on the flow redistribution.
Fichier principal
Vignette du fichier
0000167558_003.PDF (4.26 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)

Dates et versions

hal-02940079 , version 1 (18-02-2021)

Licence

Paternité - Pas d'utilisation commerciale - Pas de modification

Identifiants

Citer

Arthur Oliveira, Didier Stemmelen, Sebastien Leclerc, Tony Glantz, Alexandre Labergue, et al.. Velocity field and flow redistribution in a ballooned 7x7 fuel bundle measured by magnetic resonance velocimetry. Nuclear Engineering and Design, 2020, 369, pp.110828. ⟨10.1016/j.nucengdes.2020.110828⟩. ⟨hal-02940079⟩
76 Consultations
233 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More