2021 Volume 70 Issue 12 Pages 457-461
The Primary Containment Vessels （PCV） in Fukushima Daiichi Nuclear Power Plants （1F） have been exposed to a corrosive environment containing seawater components under irradiation condition. In such conditions, hydrogen peroxide （H2O2） is generated by water radiolysis as an oxidant in addition to dissolved oxygen. The H2O2 concentration is able to be estimated by radiolysis calculations.
The corrosion tests under gamma-ray irradiation were performed. It was confirmed that the N2 gas purging performed in the PCV is effective in inhibiting the corrosion of carbon steel under irradiation conditions.
The weight losses of carbon steel specimens obtained in the corrosion tests under gamma-ray irradiations, are evaluated using O2 and H2O2 concentrations estimated by radiolysis calculations. As a result, it is confirmed that the corrosion rate of carbon steel under irradiation is determined by the sum of diffusion limiting currents of O2 and H2O2 as well as that of carbon steel in the O2 and H2O2 coexistent conditions under non-irradiation.
