Capsule used for irradiation creep test

In a capsule used for irradiation creep test, a fuel can undergoes creep deformation by the stresses due to internal pressure to increase the outer diameter. When the outer diameter is increased, the volume of the capsule used for irradiation creep test is increased to reduce the pressure at the inside. Accordingly, the stresses applied to the fuel can not be kept constant, failing to exactly measure the creep characteristics of the fuel can material. In view of the above, in a capsule for irradiation creep test in which inert gases at high pressure are sealed in a hollow cylindrical fuel can, an aperture is formed to one of end plugs of the capsule and a thick walled tube sealed on one side is connected to the apertured end plug, in order to decrease the stress reduction accompanying the outer diameter change of the fuel can. The stresses applied to the thick walled tube due to the internal pressure is lower than the stress applied to the fuel can, the increment for the outer diameter and the increase of the volume are also smaller. Accordingly, the accuracy for the measurement of creep characteristics can be improved. (K.M.)