Interaction of ruthenium tetroxide with iodine-covered surfaces of materials in nuclear reactor containment building

Artikel i vetenskaplig tidskrift, 2016

Volatile iodine and ruthenium species are likely to be released from the fuel during a severe nuclear accident. Both iodine and ruthenium are expected to deposit on the surfaces in the containment building of the nuclear power plant. It is assumed that, due to the different release times from the fuel, ruthenium will reach the containment at the time when surfaces are already deposited with iodine species. The influence of ruthenium tetroxide on elemental iodine-covered surfaces in the containment of nuclear power plants was studied in this work. The ability of ruthenium tetroxide to oxidize iodine deposits on zinc, aluminum, copper and epoxy paint at high humidity conditions was evaluated. Quantification of both iodine and ruthenium deposits was done by the means of gamma spectroscopy. The chemical speciation of deposited elements was observed with SEM, XPS and EDX techniques. Experiments showed that ruthenium tetroxide oxidized iodine deposits into the volatile forms of iodine on zinc and aluminum samples and higher iodine oxides in the case of copper and epoxy paint samples. A major increase of ruthenium uptake on iodine-exposed surfaces in comparison to clean surfaces was observed.