The fuel for the high-temperature gas-cooled reactor consists of uranium and thorium species in the form of microspheres encapsulated in layers of pyrolytic carbon and silicon carbide and bonded into fuel rods. An important characterization of these particles is the fraction in a particular sample or rod that may have defective coatings that would allow the release of gaseous and metallic fission products. In the chlorine leach method for this determination, the fuel exposed by defective coatings is volatilized as the heavy metal chlorides at 1000°C. This method is now adapted for the examination of irradiated fuel rods in a hot cell. It is also extended to chlorinations at 1500°C by induction heating, permitting the rapid examination (2 to 3 h) of unirradiated fuel rods.