Packing experiment of breeder pebbles into water cooled solid breeder test blanket module for ITER

This paper describes an experiment in which Li2TiO3 tritium breeder pebbles were packed into a full-scale breeder pebble container (BPC) mockup. The BPC mockup, part of the Japanese water cooled solid breeder (WCSB) – Test Blanket Module (TBM) project, has been successfully developed using a reduced activation ferritic/martensitic steel, F82H. The BPC mockup was fabricated using a fiber laser welding technique, selected for its high focusing capability. Membrane panels, tube plates and side walls were joined by fiber laser welding to form the BPC. Its dimensions are 74 mm × 112 mm × 990 mm. It was confirmed to be gastight under pressurized helium up to 0.5 MPa. Packing tests were performed with real breeder material Li2TiO3 pebbles of 1 mm diameter. X-ray tomography revealed that dense packing was uniformly achieved throughout the BPC mockup.