Irradiation capsule for reactor and temperature control method therefor

The present invention provides a method of unifying the temperature of irradiation specimens and keeps them at an optional temperature upon conducting an irradiation test for materials while keeping irradiation specimens at a predetermined temperature by using gamma heat generation of gamma rays generated in a reactor core of various kinds of reactors. Namely, an irradiation capsule is incorporated in an assembly for irradiation test. An electric heater for temperature control is incorporated in the irradiation capsule. The winding pitch of the electric heater is changed so as to be dense at a place where the gamma heat generation distribution in the reactor is small, and thin at places where that is large. Alternatively, the temperature control is conducted so as to keep the temperature of the irradiation specimens to a predetermined level by controlling the supply of current to the electric heater incorporated in the irradiation capsule. According to the method as described above, the influence of the change of power in the reactor or gamma heat generation distribution is eliminated. As a result, this contributes to the improvement of the accuracy of irradiation test data. (I.S.)