The High temperature gas cooled reactor fuel

Sawa, Kazuhiro; Ueta, Shohei   ; Iyoku, Tatsuo

This paper provides present status of research and development for the coated fuel particle (CFPs) including the advanced ZrC-CFP. Current HTGR employs so-called TRISO-CFPs with SiC layer. In safety design of the HTGR fuels, it is important to retain fission products within CFPs so that their release to primary coolant does not exceed an acceptable level. The behavior of TRISO-CFPs has been investigated through experiments and reactor operation. These data show excellent performance of the TRISO-CFPs when they are correctly fabricated. On the other hand, the crystalline material comprising the SiC layer has a tendency to decompose at high temperature. The transition temperatures of beta-SiC (as-deposited) to alpha-SiC vary from 1600 to 2200C. ZrC is one of the transition metal carbides which are characterized by the high melting point and the thermodynamic stability etc. The CFPs with CVD-ZrC coatings have been investigated including the fabrication processes and characterization techniques developments.