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Study of RuO4 decomposition in dry and moist air



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Titre de la revue : Radiochimica Acta Volume : 95 N° : 11 Pagination : 643-656 Date de publication : 01/11/2007

Type de document > *Article de revue

Mots clés > accident grave, décomposition, ruthénium dioxide, ruthénium tetroxide, terme source

Unité de recherche > IRSN/DPAM/SEMIC/LETR

Auteurs > CANTREL Laurent, MADIC Charles, MUN Christian

Date de publication > 01/11/2007


During a hypothetical severe nuclear accident on a pressurized water reactor (PWR), it is of primary importance to assess potential radionuclide release into the environment, and thus to better understand the volatile ruthenium tetroxide stability, in the containment building, due to its high radiotoxicity. The stability of RuO4(g) in dry and moist air, in conditions representative of a PWR containment building, is investigated. RuO4 decomposition occurs in bulk gas phase, without any specific affinity with surfaces. The kinetic rate law of RuO4 reduction is found dependent on the presence of steam. The humidity seems to play a catalytic role, as well as the presence of ruthenium dioxide deposits. The temperature is also a key parameter. In the presence of steam, the half-life times of RuO4 are found to be respectively of 5 h and 9 h at 90°C and 40°C. A chemical reaction scheme consistent with the experimental observations is proposed.