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Journal Articles

Development and validation of the eutectic reaction model in JUPITER code

Chai, P.; Yamashita, Susumu; Yoshida, Hiroyuki

Annals of Nuclear Energy, 145, p.107606_1 - 107606_13, 2020/09

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The eutectic reaction model in JUPITER code was validated against two series of experimental tests that performed by JAEA. An experiment that aimed to evaluate the eutectic reaction between Zircaloy and Stainless steel, was simulated by JUPITER code to validate its reliability on predicting the binary eutectic reaction phenomenon. A comparison of the simulation and experimental results demonstrates good agreement on the increase rate of the solution depth at various temperature environments. Another series of tests which aimed to predict the eutectic reaction between the control rod blade and channel box in BWR, were simulated by JUPITER code to test its applicability on predicting the eutectic reaction between multiple mixture components. Although the deviation could not be completely eliminated, the reaction performance in the experiment was reasonably reproduced. As a result, it could be concluded that JUPITER code is feasible to predict the eutectic reaction behavior in nuclear severe accident.

Journal Articles

Experimental determination of the emissivity of nuclear graphite at high temperature conditions

Chai, P.; Wu, Y.*; Okamoto, Koji

Mechanical Engineering Letters (Internet), 6, p.20-00204_1 - 20-00204_7, 2020/00

In a High-Temperature Gas-cooled Reactor (HTGR), radiation is the dominant form of heat transfer due to the high temperature environment. Therefore, the emissivity of the core materials (mainly nuclear grade graphite) is important for reactor safety assessment. In this paper, the emissivity of nuclear grade graphite IG-110 was measured in the temperature range from 500$$^{circ}$$C to 1000$$^{circ}$$C by using an infrared thermometer. Besides, the impact of the graphite oxidation, which may take place in a postulated air ingress accident, was also evaluated. As a result, it was found that the emissivity of IG-110 grade graphite decreases slightly as the temperature increase. Moreover, a relatively high emissivity was detected in the pre-oxidized specimen. Based on the measurement data, two experimental correlations were suggested for the engineering applications. It could also be concluded that the commonly used value of the graphite emissivity (0.8), is conservative for engineering judgment.

Journal Articles

Validation and verification for the melting and eutectic models in JUPITER code

Chai, P.; Yamashita, Susumu; Nagae, Yuji; Kurata, Masaki

Proceedings of 9th Conference on Severe Accident Research (ERMSAR 2019) (Internet), 14 Pages, 2019/03

In order to obtain a precise understanding of molten material behavior inside RPV and to improve the accuracy of the SA code, a new computational fluid dynamics (CFD) code with multi-phase, multi-physics models, which is called JUPITER, was developed. It optimized the algorithms of the multi-phase calculation. Besides, the chemical reactions are also modeled carefully in the code so that the melting process could be treated precisely. A series of verification and validation studies are conducted, which show good agreement with analytical solutions and previous experiments. The capabilities of the multi-physics models in JUPITER code provide us another useful tool to investigate the molten material behaviors in the relevant severe accident scenario.

Journal Articles

International challenge to model the long-range transport of radioxenon released from medical isotope production to six Comprehensive Nuclear-Test-Ban Treaty monitoring stations

Maurer, C.*; Bar$'e$, J.*; Kusmierczyk-Michulec, J.*; Crawford, A.*; Eslinger, P. W.*; Seibert, P.*; Orr, B.*; Philipp, A.*; Ross, O.*; Generoso, S.*; et al.

Journal of Environmental Radioactivity, 192, p.667 - 686, 2018/12

 Times Cited Count:8 Percentile:47.43(Environmental Sciences)

It is very important to understand the impact for CTBT stations caused by radioxenon emitted from medical isotope production facilities for detection of underground nuclear tests. Predictions of the impact on six CTBT radionuclide stations in the Southern Hemisphere of radioxenon emitted from the medical isotope production facility in Australia were carried out by participants from ten nations using ATM (Atmospheric Transport Modeling) based on the emission data of radioxenon from this facility, as part of study on impact of radioxenon emitted from medical isotope production facilities on CTBT radionuclide stations.

Journal Articles

Numerical simulation of MCCI based on MPS method with different types of concrete

Chai, P.; Kondo, Masahiro*; Erkan, N.*; Okamoto, Koji*

Annals of Nuclear Energy, 103, p.227 - 237, 2017/05

 Times Cited Count:10 Percentile:79.25(Nuclear Science & Technology)

A two-dimensional computational code was developed using multi-physics models to simulate MCCI phenomena based on the moving particle semi-implicit (MPS) method. In contrast to previous studies, gas generation was simulated by calculating the force balance of the bubbles in the liquid pool in order to investigate its influence on the ablation behavior. Moreover, chemical reaction was modeled by calculating the heat release from the redox reaction between the corium and melted concrete during the erosion process. CCI-2 and CCI-3 tests were simulated by applying this code to study the aspects that may affect the ablation profile with different concrete types. The simulation result generally matches the experimental results on both axial and radial ablation rates. Application of the gas release and chemical reaction model suggested that one possible reason for the anisotropic ablation profile observed in the siliceous concrete tests is the heat transfer enhancement near the sidewall from the gas release and chemical reaction. In contrast, the test using limestone-rich concrete generated an isotropic ablation profile because axial ablation was also enhanced by the large gas discharge from the bottom concrete. In addition to the ablation profile, the crust formation and concrete-corium interface profile at the bottom in the CCI-3 test were reproduced with the help of the proposed models.

Journal Articles

International challenge to predict the impact of radioxenon releases from medical isotope production on a comprehensive nuclear test ban treaty sampling station

Eslinger, P. W.*; Bowyer, T. W.*; Achim, P.*; Chai, T.*; Deconninck, B*; Freeman, K.*; Generoso, S.*; Hayes, P.*; Heidmann, V.*; Hoffman, I.*; et al.

Journal of Environmental Radioactivity, 157, p.41 - 51, 2016/06

 Times Cited Count:23 Percentile:73.09(Environmental Sciences)

It is very important to understand the impact for CTBT stations caused by radioxenon emitted from nuclear facilities and medical isotope production facilities for detection of underground nuclear tests. Predictions of the impact on the CTBT radionuclide station in Germany of radioxenon emitted from the medical isotope production facility in Belgium were carried out by participants from seven nations using ATM (Atmospheric Transport Modeling) based on the emission data of radioxenon from this facility, as part of study on impact of radioxenon emitted from medical isotope production facilities on CTBT radionuclide stations.

Journal Articles

Nitration activates tyrosine toward reaction with the hydrated electron

Shi, W.-Q.*; Fu, H.-Y.*; Bounds, P. L.*; Muroya, Yusa*; Lin, M.; Katsumura, Yosuke*; Zhao, Y.-L.*; Chai, Z.-F.*

Radiation Research, 176(1), p.128 - 133, 2011/07

 Times Cited Count:3 Percentile:19.48(Biology)

3-Nitrotyrosine (3-NT) has been reported as an important biomarker of oxidative stress and potential source of reactive oxygen species (ROSs). In this work, the UV-visible absorption spectra of the transients formed by hydrated electron (e$$_{rm aq}$$$$^{-}$$) reacting with 3-NT and its derivatives were investigated, the spectra showed many characteristics of aromatic nitro anion radical. The reaction rate constants of e$$_{rm aq}$$$$^{-}$$ reacting with 3-NT, N-acetyl-3-nitrotyrosine ethyl ester (NANTE) and nitrotyrosine-containing peptide Gly-nitroTyr-Gly at neutral pH were determined, respectively, which were almost two orders of magnitude higher than that of tyrosine and tyrosine-containing peptides. The pH-dependence of e$$_{rm aq}$$$$^{-}$$ decay rate constants in presence of 3-NT was also studied.

Oral presentation

Numerical analysis for Fukushima Daiichi Unit 2

Chai, P.; Kondo, Masahiro*

no journal, , 

Oral presentation

Advanced multi-scale modeling and experimental tests on fuel degradation in severe accident conditions, 2-3; Validation and verification for the multi-physics models in JUPITER code

Chai, P.; Yamashita, Susumu; Nagae, Yuji; Kurata, Masaki

no journal, , 

Various numerical simulations were performed by JUPITER code in order to validate the reliability of its multi-physics models, which were developed for evaluating the melting and relocation behavior of the core materials. By comparing with the previous experimental results, we could conclude that JUPITER code is a useful tool on severe accident analysis.

Oral presentation

Oral presentation

Validation and verification for the multi-physics models in JUPITER code

Chai, P.; Yamashita, Susumu

no journal, , 

Various numerical simulations were performed by JUPITER code in order to validate the reliability of its multi-physics models, which were developed for evaluating the melting and relocation behavior of the core materials. By comparing with the previous experimental results, we could conclude that JUPITER code is a useful tool on severe accident analysis.

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