Corrosion preventive method for reactor core structural material in BWR type reactor

Hydrogen is injected from CRD drives. Since injected hydrogen enters directly to a not-boiled channel bypass portion and combines with oxygen, a recombination utilization efficiency is increased. Accordingly, stress corrosion cracks of structural materials of a reactor primary system can be prevented by injection of a small amount of hydrogen. In addition, an oxygen/hydrogen recombining catalyst comprising Pt or Pd is disposed to a gap between a reactor core channel and a shroud inner wall. Recombination is accelerated in the gap portion. Further, the oxygen/hydrogen recombining catalyst comprising Pt or Pd coated on the upper lattice plate reduces a corrosion potential on the surface of the upper lattice plate. (T.M.)