Radiation-induced ‘long-cell’ (macro-cell) corrosion in light water reactors

In previous papers, the author has established various ‘long-cell’ (akin to ‘macro-cell’) corrosion configurations that exist in nuclear power plants. Among these, the radiation-induced corrosion cell is an important mechanism since it plays a major role in the corrosion problems found in primary water of the nuclear power plants. There are numerous experimental evidences indicating a potential difference induced by radiation, however, the exact mechanism of such phenomena has not been clarified. The author investigated the basic mechanism by combining radiation chemistry, electrochemistry and corrosion science to confirm the existence of radiation-induced ‘long-cell’ action.By performing a competition kinetic study, eaq−, reacting mainly with stable molecules are found to be responsible for inducing a large portion of the potential difference both in the PWR and BWR water chemistry environments. The hydrated electrons react at a cathodic half-cell thereby inducing reductive reactions in the mixed cell configuration. This method reproduces the reported and experimentally observed redox potential variation to a certain extent (observed in the INCA Test Loop in Sweden and the NRI-Rez BWR-2 Loop in Czech Republic). The author believes the results support the assumed corrosion mechanism although details are still debatable.