Zinc injection device

Zinc oxide particles are charged into a metal cylinder, and high temperature water is charged into the cylinder, as well as heat generating heaters are disposed to the outer circumference of the cylinder. When purified water at high temperature is brought into contact with the zinc oxide particles in the cylinder, zinc ions are dissolved therein in accordance with the solubility of the zinc oxide. The concentration of the zinc ions flown into the reactor can be varied by changing the surface area of the zinc oxide particles. Accordingly, even when fuels causing less deposition of metal ions such as a Zr-lined fuel are loaded, deposition of the metal ions to the surface of the fuels can be promoted by always generating and injecting the zinc ions at a predetermined amount, thereby enabling to decrease radioactivity of reactor water. (T.M.)