Wheel for reactor component

The present invention concerns a wheel for a reactor component in a thermonuclear reactor. The reactor component is constituted such that it can be water-cooled by the incorporation of a cooling water channel. The reactor component has an axle, to which a wheel is fit. A metal bearing is mounted between the axle and the wheel being in close contact with the former. The axle and the metal bearing are made of materials having linear expansion coefficient substantially equal to each other, while the wheel is made of a material having a smaller linear expansion coefficient. With such a constitution, if the temperature of the reactor component is elevated by the generation of nuclear heat to elevate the temperature of the wheel and the axle, the outer diameter of the axle (the outer diameter of metal axle) is increased to greater than the hole diameter of the wheel due to the difference of the linear expansion coefficient. Accordingly, since the wheel is in close contact with the metal bearing inserted to the axle under pressure, the temperature elevation of the wheel due to the generation of nuclear heat can be lowered effectively even in a vacuum. (I.N.)