Thermal and mechanical characteristics of an instrumented capsule for a material irradiation test

In this study, the thermal and mechanical characteristics are analyzed for the structural integrity evaluation of the instrumented capsule used for the irradiation test of reactor vessel materials in the research reactor, hi-flux advanced neutron application reactor (HANARO). The temperature of test specimens inserted in the capsule mainbody by (gamma)-flux is calculated using a heat transfer code, HEATING 7.2f. The maximum temperature is 556.75 K at the center of the capsule mainbody, thus the temperature satisfies the userʹs requirement. To estimate the mechanical characteristics of the capsule due to the pressure and thermal loading, stress analysis is carried out with a finite element analysis program, ANSYS. The strength of the capsuleʹs external tube is also evaluated by considering the buckling stress of the capsule mainbody under coolant pressure loading. The results of the analysis show that the temperature distributions are significantly affected by the gap size between the holder and the specimen. The calculated stresses of the capsule structure are well within the allowable stress values of the ASME code. It is expected that the results presented in this paper will be useful in the design and safety evaluation of instrumented capsules for material irradiation tests.