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Journal Articles

Thermal decomposition of perlite concrete under different water vapor pressures

Iwasaki, Shun*; Sakai, Yasuhiro*; Kikuchi, Shin; Koga, Nobuyoshi*

Journal of Thermal Analysis and Calorimetry, 147(11), p.6309 - 6322, 2022/06

 Times Cited Count:2 Percentile:46.76(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)$$_{2}$$ and the acceleration of thermal decomposition of CaCO$$_{3}$$ were identified as specific effect of atmospheric water vapor.

Journal Articles

Influence of atmospheric CO$$_{2}$$ on the thermal decomposition of perlite concrete

Sakai, Yasuhiro*; Iwasaki, Shun*; Kikuchi, Shin; Koga, Nobuyoshi*

Journal of Thermal Analysis and Calorimetry, 147(10), p.5801 - 5813, 2022/05

 Times Cited Count:4 Percentile:71.84(Thermodynamics)

The influence of atmospheric CO$$_{2}$$ 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)$$_{2}$$ and the retardation of the thermal decomposition of CaCO$$_{3}$$ were identified as specific effect of atmospheric CO$$_{2}$$.

Journal Articles

Thermal behavior and kinetics of the reaction between liquid sodium and calcium hydroxide

Kikuchi, Shin; Koga, Nobuyoshi*

Journal of Thermal Analysis and Calorimetry, 147(7), p.4635 - 4643, 2022/04

 Times Cited Count:1 Percentile:25.85(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)$$_{2}$$(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.

Journal Articles

Thermally stimulated liquid Na-CaCO$$_{3}$$ reaction; A Physicogeometrical kinetic approach toward the safety assessment of Na-cooled fast reactors

Koga, Nobuyoshi*; Kikuchi, Shin

Industrial & Engineering Chemistry Research, 61(7), p.2759 - 2770, 2022/02

 Times Cited Count:0 Percentile:0(Engineering, Chemical)

Journal Articles

Thermal behavior of perlite concrete used in a sodium-cooled fast reactor; Multistep reaction kinetics and melting for safety assessment

Koga, Nobuyoshi*; Kikuchi, Shin

Journal of Thermal Analysis and Calorimetry, 138(2), p.983 - 996, 2019/10

 Times Cited Count:9 Percentile:54.83(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.

Journal Articles

Comparative study on the thermal behavior of structural concretes of sodium-cooled fast reactor

Kikuchi, Shin; Koga, Nobuyoshi*; Yamazaki, Atsushi*

Journal of Thermal Analysis and Calorimetry, 137(4), p.1211 - 1224, 2019/08

 Times Cited Count:8 Percentile:50.59(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)$$_{2}$$/CaCO$$_{3}$$ 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$$_{2}$$ compounds.

Journal Articles

Thermal behavior of sodium hydroxide-structural concrete composition of sodium-cooled fast reactor

Kikuchi, Shin; Koga, Nobuyoshi*

Journal of Thermal Analysis and Calorimetry, 131(1), p.301 - 308, 2018/01

 Times Cited Count:7 Percentile:38.85(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$$_{2}$$) reaction as one of possible secondary stage reactions was investigated for safety assessment of SFR. Thermal behavior of NaOH-SiO$$_{2}$$ 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$$_{2}$$ reaction occurs as rapid reaction right after NaOH melting at 583 K. Therefore, it was expected that NaOH-SiO$$_{2}$$ 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.

Journal Articles

Experimental study and kinetic analysis on sodium oxide-silica reaction

Kikuchi, Shin; Koga, Nobuyoshi*; Seino, Hiroshi; Ohno, Shuji

Journal of Nuclear Science and Technology, 53(5), p.682 - 691, 2016/05

 Times Cited Count:12 Percentile:79.93(Nuclear Science & Technology)

In a sodium-cooled fast reactor (SFR), if considering hypothetical severe accidental condition such as the steel liner failure of structural concrete caused by intensive leakage of liquid sodium (Na) coolant, the liquid sodium-concrete reaction (SCR) may take place. The major consequences of SCR are hydrogen release, energy release and concrete ablation. Thus, it is important to understand the phenomenology of SCR. As a part of a series of studies on SCR, this study focused on the reaction between sodium oxide (Na$$_{2}$$O) and silica (SiO$$_{2}$$). Through thermoanalytical and X-ray diffraction measurements, it was revealed that Na$$_{2}$$O-SiO$$_{2}$$ reaction to form sodium orthosilicate (Na$$_{4}$$SiO$$_{4}$$) occurs at significantly lower temperature in comparison with Na-SiO$$_{2}$$ reaction.

Journal Articles

Application of thermal analysis in research and development of sodium-cooled fast reactor

Kikuchi, Shin; Koga, Nobuyoshi*

Netsu Sokutei, 43(1), p.11 - 18, 2016/00

This paper describes the study on sodium-concrete reaction behavior, which is one of the example of the application of thermal analysis in research and development of sodium-cooled fast reactor (SFR).

Journal Articles

Kinetic study on liquid sodium-silica reaction for safety assessment of sodium-cooled fast reactor

Kikuchi, Shin; Koga, Nobuyoshi*; Seino, Hiroshi; Ohno, Shuji

Journal of Thermal Analysis and Calorimetry, 121(1), p.45 - 55, 2015/07

 Times Cited Count:12 Percentile:46.27(Thermodynamics)

In this study, the kinetic behavior of the sodium (Na)-silica (SiO$$_{2}$$) 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$$_{2}$$ reaction.

Oral presentation

Study on sodium-concrete reaction mechanism, 2; Consideration on reactivity of silica

Kikuchi, Shin; Seino, Hiroshi; Ohno, Shuji; Koga, Nobuyoshi*

no journal, , 

Educidation study on sodium-concrete reaction (SCR), which is one of the severe accidental condition caused by sodium leakage in sodium-cooled fast reactor, has been implemented. In this study, reactivity of silica as major element of concrete was investigated by thermal analysis and reaction mechanism was discussed on the basis of thermal measurement results.

Oral presentation

Thermal behavior of sodium hydroxide-structural concrete composition

Kikuchi, Shin; Koga, Nobuyoshi*; Seino, Hiroshi

no journal, , 

Under postulated accidental condition of sodium-cooled fast reactor, liquid sodium spilled into the floor may lead to fail the steel liner. Consequently, sodium-concrete reaction comes to occur by direct contact of liquid sodium with structural concrete. In this study, the NaOH-SiO$$_{2}$$ reaction that is one of the possible reactions was investigated using a differential scanning calorimetry (DSC) equipped with videoscope. From experimental results, sudden blowout of the reactants was observed after melting of NaOH, which is provably attributed to the sudden evaporation of water vapor. In comparison with the other possible reactions, NaOH-SiO$$_{2}$$ reaction is relatively rapid in terms of kinetics. The major solid product of NaOH-SiO$$_{2}$$ reaction was identified as sodium silicate from XRD analysis.

Oral presentation

Thermal behavior of liquid sodium-calcium carbonate reaction

Kikuchi, Shin; Koga, Nobuyoshi*

no journal, , 

Under postulated accidental condition of sodium-cooled fast reactor (SFR), liquid sodium spilled into the floor may lead to fail the steel liner. Consequently, sodium (Na)-concrete reaction (SCR) comes to occur by direct contact of liquid sodium with structural concrete. In this study, Na-calcium carbonate (CaCO$$_{3}$$) reaction was investigated using a differential scanning calorimetry (DSC). It was revealed from DSC runs that Na-CaCO$$_{3}$$ reaction initiates at approximately 726 K. Based on the DSC exothermic peaks recorded at different heating rates, kinetic analysis for the Na-CaCO$$_{3}$$ reaction was performed using Kissinger method, and the kinetic results were compared with those reported previously for the reaction of limestone concrete with sodium spill.

Oral presentation

Kinetic analysis for the multistep thermal decomposition of structural concrete of sodium-cooled fast reactor; Perlite concrete

Koga, Nobuyoshi*; Kikuchi, Shin

no journal, , 

The major structural concretes of sodium-cooled fast reactor (SFR) being tested in Japan are siliceous and perlite concretes. The thermal behavior of the concretes and the reaction behavior between liquid sodium with concretes are necessary information for the safety assessment when considering postulated serious accidents. In this study, the thermal decomposition behavior of the perlite concrete was investigated using a range of thermoanalytical techniques, and the complex reaction behavior was characterized kinetically.

Oral presentation

Thermal decomposition of siliceous concrete under elevating temperature

Kikuchi, Shin; Koga, Nobuyoshi*; Seino, Hiroshi

no journal, , 

In a postulated severe accidental condition of sodium-cooled fast reactor (SFR) such as core melt through, molten core materials containing liquid metals and fuels heated to very high temperatures may attack the structural concretes. This would cause Molten Core-Concrete Interaction (MCCI). MCCI gives extreme thermal loading to the structural concretes and results in their erosion and decomposition. In this study, for elucidating the thermal behavior of the siliceous concretes of SFR at high temperatures, Thermogravimetry-Differential Thermal Analysis (TG-DTA) measurements were carried out for the tight sandstone concrete. It was revealed that offset of melting of the siliceous concretes was appoximately 1300-1400 $$^{circ}$$C.

Oral presentation

Development of multi-level, multi-scenario simulation systems for sodium cooled fast reactor, 4; Experimental database construction for code V&V

Kikuchi, Shin; Kurihara, Akikazu; Koga, Nobuyoshi*; Deguchi, Yoshihiro*; Takata, Takashi; Ohshima, Hiroyuki

no journal, , 

Development of multi-level, multi-scenario simulation systems for the safety fundamental technology of sodium cooled fast reactor is under way. In this study, authours report the experimental plan and current status on sodium fire and sodium-concrete reaction as important specific events of sodium cooled fast reactor for code V&V.

Oral presentation

Comparative kinetic study for the thermal decomposition of structural concretes used in the sodium-cooled fast reactor

Koga, Nobuyoshi*; Kikuchi, Shin

no journal, , 

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, thermal decomposition behaviors of siliceous and perlite concretes used in the nuclear power plant were comparatively investigated using thermoanalytical techniques.

Oral presentation

Development of multi-level, multi-scenario simulation systems for sodium cooled fast reactor, 1; Overall plan for development of simulation systems

Ohshima, Hiroyuki; Takata, Takashi; Doda, Norihiro; Kikuchi, Shin; Koga, Nobuyoshi*; Deguchi, Yoshihiro*

no journal, , 

Development of multi-level, multi-scenario plant simulation systems has started as a fundamental technology to support mechanism elucidation of phenomena, design optimization, and innovative technology development toward the commercialization of sodium cooled fast reactors. In this presentation, the overall plan of this development project is introduced.

Oral presentation

Kinetic study of liquid sodium-calcite reaction for safety assessment of sodium cooled fast reactor

Kikuchi, Shin; Koga, Nobuyoshi*

no journal, , 

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-calcite reaction was investigated using a differential scanning calorimetry. Comparative study for the reactions of pellet and powder of the reagent CaCO3 with sodium was performed from the viewpoints of thermal behaviour and reaction kinetics.

Oral presentation

Thermal decomposition of structural concretes used in the sodium-cooled fast reactor; Perlite and siliceous concretes

Koga, Nobuyoshi*; Kikuchi, Shin

no journal, , 

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.

28 (Records 1-20 displayed on this page)