Safety criteria and quality control of HTTR fuel

摘要

In the high temperature gas-cooled reactor (HTGR), coated fuel particles are employed as fuel to permit high outlet coolant temperature. In current HTGRs, Tri-isotropic (TRISO) coated fuel particles are employed as fuel. The TRISO coatings consist of a low-density, porous pyrolytic carbon (PyC) buffer layer adjacent to the spheri- cal fuel kernel, followed by an isotropic PyC layer (inner PyC; IpyC), a silicon carbide (SiC) layer and a final PyC (outer PyC; OPyC) layer as shown in Fig. 1. In safety design of the HTGR fuels, it is important to retain fission products within particles so that their release to primary coolant does not exceed an acceptable level (Saito et al., 1994).