K. Minato et al., IMPROVEMENTS IN QUALITY OF AS-MANUFACTURED FUELS FOR HIGH-TEMPERATUREGAS-COOLED REACTORS, Journal of Nuclear Science and Technology, 34(3), 1997, pp. 325-333
The mechanisms of coating failure of the fuel particles for the high-t
emperature gas-cooled reactors during coating and compaction processes
of the fuel fabrication were studied to determine a way to reduce the
defective particle fraction of the as-manufactured fuels. Through the
observation of the defective particles, it was found that the coating
failure during the coating process was mainly caused by the strong me
chanical shocks to the particles given by violent particle fluidizatio
n in the coater and by unloading and loading of the particles. The coa
ting failure during the compaction process tvas probably related to th
e direct contact with neighboring particles in the fuel compacts. The
coating process was improved by optimizing the mode of the particle fl
uidization and by developing the process without unloading and loading
of the particles at intermediate coating process. The compaction proc
ess was improved by optimizing the combination of the pressing tempera
ture and the pressing speed of the overcoated particles. Through these
modifications of the fabrication process, the quality of the as-manuf
actured fuel compacts was improved outstandingly.