Measurement of effective thermal conductivity of lithium oxide and beryllium sphere packed bed

Effective thermal conductivity of Li₂O and Be sphere packed bed was measured for the design of pebble layered type breeding blanket of ITER (CDA). Measurement runs were performed with 1 mmφ Be sphere in the temperature range of 150 C to 650 C for Li₂O and 130 C to 320 C for Be. As the result, the effective thermal conductivity of 1 mmφ Li₂O was influenced by contact area between spheres and packing fraction due to its reactivity. The measured value was about 0.9 W/mK with the packing fraction of 48%. Effective thermal conductivity of 1,2 and 3 mmφ Be sphere packed beds were observed as k=1.56+3.25×10^-2 T, k=2.43+2.15×10 ^-3 T, k=2.51+1.45×10^-3 T, respectively, where k is effective thermal conductivity [W/mK] and T is temperature [C]. Measured packing fraction was 56, 61 and 64% for 1, 2 and 3 mmφ Be