Boiling and drying accident of high-level liquid waste in a reprocessing plant: Examination of the NO2 and NO generation using the simulated waste |
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| Authors: | Takashi Kodama Hiroshi Kinuhata Yuki Shibata Mikio Kumagai Kazunori Suzuki Shin-Itiro Hayashi |
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| Affiliation: | 1. Safety and Quality Division, Japan Nuclear Fuel Ltd , Aomori, Japan matsuoka@uigiken.com;3. Safety and Quality Division, Japan Nuclear Fuel Ltd , Aomori, Japan;4. UI Sciences Inc ., Tokyo, Japan |
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| Abstract: | ABSTRACT NO2 and NO generated during a boiling and drying accident, which affects the release of volatilized radioactive Ru into the atmosphere, were examined using various samples including simulated high-level liquid waste and a thermogravimetric analyzer. NO2 and NO in the gas flowing out of the analyzer were measured separately using a NOx analyzer equipped with NO2 and NO sensors. The samples were heated to 600°C at constant heating rates of mainly 0.2 and 1°C min?1 that was adopted taking into account the decay heat of high-level liquid waste. It was found that under 180°C some nitrates in the liquid waste mainly separated their nitrate groups as HNO3 without generating NOx (a mixture of NO and NO2) and above 300°C the residual HNO3 in the waste participated in thermal decomposition generating NOx. The generation rates of NO2 and NO were obtained as a function of time using Arrhenius type equations, and the O2 rate was derived from these equations using the stoichiometry of the reactions that generate NO2, NO, and O2. |
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| Keywords: | Reprocessing high-level liquid waste severe accident boiling NO2 NO RuO4 NOx O2 drying |
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