Evaluation on BDI of large diameter pin bundles by out-of-pile bundle compression test

Uwaba, Tomoyuki ; Ichikawa, Shoichi; Katsuyama, Kozo 

Bundle-Duct Interaction (BDI) in core fuel subassemblies in FBRs is a limiting factor for fuel burnup. Thus, BDI is an important evaluation item in the upgraded core of the Monju prototype FBR and the demonstration FBR studied in the FaCT project because the fuel subassemblies are to be used to high burnup condition. Since fuel subassemblies of these FBRs consists of large diameter fuel pins, the out-of-pile bundle compression test with large diameter pins was performed to evaluate their BDI bundle. In the compression test, bundle cross-sectional images (CT images) were obtained by using the X-ray computer tomography. The CT images were numerically analyzed to evaluate the deformation of pin bundles due to BDI. The evaluation results revealed that deformation of large diameter pin bundles are controlled by pin bowing and cladding oval-distortion the same as in the case of currently used small diameter pin bundles.