Fire Science and Technology
Online ISSN : 1882-0492
Print ISSN : 0285-9521
ISSN-L : 0285-9521
  • Yukiko Chatani, Kazunori Harada
    2024 年 43 巻 1 号 p. 1-16
    発行日: 2024年
    公開日: 2024/05/20
    ジャーナル フリー
    Char oxidation during the cooling period after a fire is one of the important factors in the self-extinguishment of a timber structural element because it involves a large amount of he at generation. In this study, the char oxidation rates of larch glue laminated timber were measured at various heating intensities, using a cone calorimeter. At a heating intensity of 12.4 kW/m2, char oxidation continued with a mass loss rate of 2.41 × 10-3 kg/m2s and a surface temperature of 501.8°C. At a heating intensity of 8.4 kW/m2, self-stopping of char oxidation occurred with a mass loss rate of 0.12 × 10-3 kg/m2s, which can be regarded as being close to zero. From all the measured values, it was concluded that the char oxidation ceases if the heating intensity is less than 8.4 kW/m2 and if the surface temperature is less than 286.2°C. We also developed a formula to describe the relationship between the mass loss rate and the surface temperature during char oxidation, using an Arrhenius equation. The heat of combustion of the char layer was 23.41MJ/kg in average. Using the conditions and equations obtained from our measurements, it is possible to predict the behaviour of char oxidation in response to temperature of timber structural element. In the future, these values could be applied to a heat conduction calculation programme, which would make it possible to predict the self-stopping of char oxidation by calculation.
  • Hijiri Nishimura, Kousei Katsusima, Zonta Miyamoto, Shunki Sato, Touya ...
    2024 年 43 巻 1 号 p. 17-24
    発行日: 2024年
    公開日: 2024/05/20
    ジャーナル フリー
    This short comment highlights the importance of volatile ruthenium compounds in the nuclear fuel cycle and nuclear power generation. Focusing on its volatile properties, we elucidate its behavior in reprocessing and radiotherapy and explore its impact on safety and efficiency improvements. This study focuses on the partitioning behavior of ruthenium and europium in organic solvents under fire of reprocessing plants and their release behavior during organic solvent combustion, providing important data from a safety perspective. A thorough study of the chemistry of radioactive Ru was conducted, providing detailed information on its behavior and reactions. This study provides essential information for nuclear waste management and other nuclear-related fields. Concerning the behavior of Ru in nitric acid solutions during evaporation and drying, the influence of coexisting nitrates on the formation of ruthenium tetroxide (RuO4) is mentioned in detail. In addition, a staining method for transmission electron microscopy (TEM) using RuO4 is commonly used to observe the microstructure of polymeric materials. Furthermore, two crystal structures of RuO4 were discovered regardless of their volatile properties. The information collected here will contribute to the chemical knowledge of effective strategies for fire safety in power generation and waste treatment.