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Suche nach „[M.] [Flad]“ hat 3 Publikationen gefunden
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    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    F. Gabrielli, W. Maschek, Rui Li, C. Matzerath Boccaccini, M. Flad, S. Gianfelici, B. Vezzoni, A. Rineiski

    Probabilistic evaluation of the energetics upper bound during the transition phase of an unprotected loss of flow accident for a sodium cooled fast reactor by using a Phenomenological Relationship Diagram

    Nuclear Engineering and Design, vol. 341, no. 146-154

    2019

    DOI: 10.1016/j.nucengdes.2018.11.004

    Abstract anzeigen

    One of the main research goals of the GEN-IV systems is enhancing their safety compared with the former Sodium-Cooled Fast Reactor (SFR) designs. A key issue is the capability of accidents prevention as well as of demonstrating that their consequences do not violate the safety criteria. In order to fulfill such requirements, risk analyses of severe core disruptive accidents are performed. Since the beginning of the SFR development, Hypothetical Core Disruptive Accidents (HCDAs) have played an outstanding role. Numerous safety analyses have been performed for developing and licensing past SFR designs and nowadays a large database of results is available. In particular, a large amount of results of the mechanistic SIMMER-II and SIMMER-III/IV analyses for various core designs and different power classes is available at the Karlsruhe Institute of Technology (KIT). The current paper describes the probabilistic approach based on the Phenomenological Relationship Diagram (PRD), which is used to evaluate the Probability Distribution Function (PDF) of the thermal energy release during the transition phase of an unprotected loss of flow accident scenario for a SFR. The technique allows taking into account the mechanistic nature of the accident scenario. In fact, the available results of the mechanistic analyses of HCDAs in SFRs are used to assess the PDFs of the dominant phenomena affecting the thermal energy release, which are propagated in the PRD by employing a Monte Carlo method.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    L. Guo, Rui Li, S. Wang, M. Flad, W. Maschek, A. Rineiski

    Numerical investigation of SIMMER code for fuel-coolant interaction

    International Journal of Hydrogen Energy, vol. 41, no. 17, pp. 7227-7232

    2016

    DOI: 10.1016/j.ijhydene.2016.01.080

    Abstract anzeigen

    Fuel-coolant interaction (FCI) is a very complex but important issue in the safety analysis of the severe accidents for nuclear reactors due to the rapid multiple thermos–hydrodynamic activities. Until now, there are still large uncertainties existing in various phases during the FCI process, such as the melt solidification, fragmentation and relocation, film boiling on the melt surface, coolant vaporization and following vapor explosion, and so on. SIMMER-III code was first developed to analyses core disruptive accidents in liquid-metal fast reactors (LMFRs) as an integral numerical tool coupling multiphase thermal hydraulic code with neutron kinetics model, and was demonstrated its reasonable flexibility in some FCI simulations. In this paper, the applicability of the code in simulating the premixing phase of FCI process is verified in comparison with a related jet-type experiment in literature. In addition, the sensitivity analysis on several key parameters of the related models in the SIMMER code was performed to assess the impacts in the simulation of the FCI premix phase. It is expected that the results can provide some numerical experience for the uncertainty analysis of FCI calculation using SIMMER-III code.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    Rui Li, W. Maschek, C. Matzerath Boccaccini, B. Vezzoni, M. Flad, A. Rineiski

    Impact of the Bell–Plesset instability on centralized sloshing in pool geometry

    International Journal of Hydrogen Energy, vol. 41, no. 17, pp. 7126-7131

    2016

    DOI: 10.1016/j.ijhydene.2016.01.152

    Abstract anzeigen

    The theoretical and numerical analyses have been conducted to investigate the kinetic energy attenuation characteristics on basis of identical geometry and liquid properties together with an existing centralized sloshing experiment. The goal of this paper is to assess the quantitative impact of the Bell–Plesset (BP) instability on the sloshing motion. The results show that BP instability plays a certain role in azimuthal energy dissipation when the sloshing waves are moving inwards and converging in cylindrical geometry. The velocity attenuation is calculated via a perturbation flow equation assuming the initial perturbation length 1 mm, it shows that the velocity could be suppressed by 25% due to BP instability. The corresponding simulation using particle method has been performed. With the help of numerical simulation, the initial perturbation length is approximated as 1.3 mm which is in line with the assumption in the theoretical analysis.