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Iwasaki, Shun*; Sakai, Yasuhiro*; Kikuchi, Shin; Koga, Nobuyoshi*
Journal of Thermal Analysis and Calorimetry, 147(11), p.6309 - 6322, 2022/06
Times Cited Count：5 Percentile：41.15(Thermodynamics)The influence of atmospheric water vapor on the multistep thermal decomposition of perlite concrete was investigated in detail by separating the component reaction steps using kinetic deconvolution analysis (KDA). The retardation of thermal decomposition of Ca(OH)
and the acceleration of thermal decomposition of CaCO
were identified as specific effect of atmospheric water vapor.
on the thermal decomposition of perlite concreteSakai, Yasuhiro*; Iwasaki, Shun*; Kikuchi, Shin; Koga, Nobuyoshi*
Journal of Thermal Analysis and Calorimetry, 147(10), p.5801 - 5813, 2022/05
Times Cited Count：8 Percentile：59.41(Thermodynamics)The influence of atmospheric CO on the multistep thermal decomposition of perlite concrete was investigated in detail by separating the component reaction steps using kinetic deconvolution analysis (KDA). The carbonation of Ca(OH) and the retardation of the thermal decomposition of CaCO were identified as specific effect of atmospheric CO.
Kikuchi, Shin; Koga, Nobuyoshi*
Journal of Thermal Analysis and Calorimetry, 147(7), p.4635 - 4643, 2022/04
Times Cited Count：1 Percentile：7.32(Thermodynamics)In a sodium-cooled fast reactor (SFR), sodium-concrete reaction (SCR) may probably occur when liquid sodium from cooling system spilled into the floor may lead to fail the steel liner as protector of the structural concretes. The structural concretes of SFR comprises siliceous concreate as main body of reactor structure and perlite concrete placed between the steel liner and the siliceous concrete serving as a protector and an insulator, respectively. Therefore, the reaction behaviour between the perlite concrete and liquid sodium in the early stage of SCR should be focused. In this study, for the first step of elucidation on SCR, thermal behaviour of sodium-calcium hydroxide reaction was investigated using a differential scanning calorimetry (DSC). It was revealed that the reaction between Na(l) and Ca(OH)(s) initiates at approximately 550 K, producing the product layer composed of CaO(s) and NaOH(s), which is evident from XRD pattern of solid product after DSC measurement. The kinetic consideration of the cited reaction was carried out to obtain the activation energy.
Koga, Nobuyoshi*; Kikuchi, Shin
Journal of Thermal Analysis and Calorimetry, 138(2), p.983 - 996, 2019/10
Times Cited Count：11 Percentile：48.25(Thermodynamics)Detailed understanding of the thermal decomposition of the structural concretes used in the sodium-cooled fast reactor is essentially important to simulate the possible phenomena that occurs under postulated severe accident of the nuclear power plant. In this study, the thermal decomposition behaviour of a perlite concrete and two siliceous concretes used in a sodium-cooled fast reactor was comparatively investigated.
Kikuchi, Shin; Koga, Nobuyoshi*; Yamazaki, Atsushi*
Journal of Thermal Analysis and Calorimetry, 137(4), p.1211 - 1224, 2019/08
Times Cited Count：9 Percentile：41.34(Thermodynamics)In this study, two siliceous concretes with similar specification as structural concretes of SFR were selected for the comparative study of the thermal behavior. The thermal behavior of the structural concretes was investigated in a temperature range from room temperature to 1900 K using TG-differential thermal analysis (DTA) and other supplementary techniques. The softening and melting of the concretes initiated in the thermal decomposition product of the cement portion in the temperature range 1400-1600 K. Because the compositional difference between the cement portion of two different siliceous concretes was characterized by different Ca(OH)/CaCO ratios, the melting temperature ranges of those thermal decomposition products are not so significantly different. On the other hand, the melting of the aggregate is directly influenced by the initial composition of SiO compounds.
Kikuchi, Shin; Koga, Nobuyoshi*
Journal of Thermal Analysis and Calorimetry, 131(1), p.301 - 308, 2018/01
Times Cited Count：8 Percentile：34.02(Thermodynamics)Under postulated accidental condition of sodium-cooled fast reactor (SFR), liquid sodium spill into the floor may lead to fail the steel liner resulting in sodium-concrete reaction (SCR). In this study, the sodium hydroxide (NaOH)-silica (SiO) reaction as one of possible secondary stage reactions was investigated for safety assessment of SFR. Thermal behavior of NaOH-SiO reaction such as reaction onset was determined using a differential scanning calorimetry (DSC). As a result of DSC measurement, it was revealed that NaOH-SiO reaction occurs as rapid reaction right after NaOH melting at 583 K. Therefore, it was expected that NaOH-SiO reaction is dominant in the time frame of secondary stage of SCR if significant amount of NaOH has been generated during the initial stage reaction.
Kikuchi, Shin; Koga, Nobuyoshi*; Seino, Hiroshi; Ohno, Shuji
Journal of Thermal Analysis and Calorimetry, 121(1), p.45 - 55, 2015/07
Times Cited Count：13 Percentile：44.45(Thermodynamics)In this study, the kinetic behavior of the sodium (Na)-silica (SiO) reaction was investigated for an assessment method of reactivity/stability of siliceous concrete against the sodium-concrete reaction (SCR) by postulating a severe accidental condition in the sodium-cooled fast reactor (SFR). The reaction behavior was tracked using a differential scanning calorimetry (DSC) equipped with a videoscope for viewing the changes in the sample during the reaction. From detail kinetic analysis, it was revealed that the kinetic results determined from the kinetic data at the maximum reaction rate can be interpreted as is for the major reaction stage. In addition, the k value at a constant temperature calculated using the Arrhenius parameters determined by the simplified Kissinger method can be used for the reactivity/stability assessment of the siliceous concrete in view of the kinetics of the major reaction stage of the Na-SiO reaction.
Sakuma, Takashi*; Xianglian*; Siagian, S.*; Basar, K.*; Takahashi, Haruyuki*; Igawa, Naoki; Kamishima, Osamu*
Journal of Thermal Analysis and Calorimetry, 99(1), p.173 - 176, 2009/10
Times Cited Count：4 Percentile：16.34(Thermodynamics)Neutron diffraction measurements have been performed on powder VSe at 294 K. The diffuse scattering theory including correlation effects among thermal displacements of atoms is applied to background function in the rietveld analysis. The oscillatory scheme of the diffuse scattering intensity from hexagonal VSe is explained by the correlation effects among far-neighboring Se-Se atoms. The values of the correlation effects depend on the inter-atomic distance and not on the crystal structure.
