A capsule is the device for irradiation test of nuclear materials and fuels in HANARO. The instrumentation cables are sealed tightly by brazing at the top of the capsule. In this study, the integrities at the brazing of both Inconel 600 and STS 310 materials were confirmed by tensile test, survey of damage on coating, and measurement of insulation resistance. At tensile test, brazing areas were not damaged but the thermocouples themselves were broken on both the materials. At flame heat test, the coating of STS 310 material was maintained without damage but the brittle fracture on Inconel 600 material was observed. Insulation resistances were confirmed to be satisfactory in case of both the materials. In this analysis, the thermocouple was expanded by 0.81mm on the direction of y-axis and the tube was contracted by 0.57mm on the direction of x-axis. As the result, cracks might be occurred with thermal stresses. EDX spectrum analysis showed that the BAg-1 filler metal formed a thin reaction layer on the surface of brazed metal.

The irradiation tests of materials in HANARO have been performed usually at temperatures below 300℃ at which the RPV(Reactor Pressure Vessel) materials of the commercial reactors such as the light water reactor and CANDU are operated. As VHTR(Very High Temperature Reactor) and SFR (Sodium-cooled Fast Reactor) projects are being carried as a part of the present Gen-IV program in Korea, the requirements for irradiation of materials at temperatures higher than 500℃ are recently being gradually increased. To overcome the restriction in the use at high temperature of the existing Al thermal media, a new capsule with double thermal media composed of two kinds of materials such as Al-Ti and Al- graphite was designed and fabricated more advanced than the single thermal media capsule. At the irradiation test of the capsule, the temperature of the specimens successfully reached 700℃ and the integrity of Al, Ti and graphite material was maintained.