Sökning: "Ma Weimin"

Visar resultat 1 - 5 av 8 avhandlingar innehållade orden Ma Weimin.

  1. 1. An Experimental Study on the Dynamics of a Single Droplet Vapor Explosion

    Författare :Roberta Concilio Hansson; Weimin Ma; Geroges Berthoud; KTH; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; steam explosions; radiography; melt preconditioning; noncondensable gas; Low energy physics; Lågenergifysik;

    Sammanfattning : The present study aims to develop a mechanistic understanding of the thermal-hydraulic processes in a vapor explosion, which may occur in nuclear power plants during a hypothetical severe accident involving interactions of high-temperature corium melt and volatile coolant. Over the past several decades, a large body of literature has been accumulated on vapor explosion phenomenology and methods for assessment of the related risk. LÄS MER

  2. 2. Sensitivity and Uncertainty Analysis of Boiling Water Reactor Stability Simulations

    Författare :Ivan Gajev; Weimin Ma; Tomasz Kozlowski; Kostadin Ivanov; KTH; []

    Sammanfattning : The best estimate codes are used for licensing of Nuclear Power Plants (NPP), but with conservative assumptions. It is claimed that the uncertainties are covered by the conservatism of the calculation. LÄS MER

  3. 3. An Experimental Study on Micro-Hydrodynamics of Evaporating/Boiling Liquid Film

    Författare :Shengjie Gong; Ma Weimin; Horst-Michael Prasser; KTH; []
    Nyckelord :liquid film; critical thickness; boiling; critical heat flux; rupture; dry spot; confocal optical sensor; SRA - Energy; SRA - Energi;

    Sammanfattning : Study of liquid film dynamics is of significant importance to the understanding and control of various industrial processes that involve spray cooling (condensation), heating (boiling), coating, cleaning and lubrication. For instance, the critical heat flux (CHF) of boiling heat transfer is one of the key parameters ensuring the efficiency and safety of nuclear power plants under both operational and accident conditions, which occurs as the liquid layers (microlayer and macrolayer) near the heater wall lose their integrity. LÄS MER

  4. 4. Numerical Investigations on Debris Bed Coolability and Mitigation Measures in Nordic Boiling Water Reactors

    Författare :Zheng Huang; Weimin Ma; Florian Fichot; KTH; []
    Nyckelord :Severe accident; Debris bed; Coolability; Quench; Oxidation; MEWA code; Coupled analysis; Svåra haverier; Grusbädd; Kylbarhet; Kylning; Oxidering; MEWA program; Kopplad analys; Physics; Fysik;

    Sammanfattning : This thesis is aiming at coolability assessment of particulate debris beds formed in hypothetical severe accidents of Nordic boiling water reactors (BWRs) which may employ either lower drywell flooding or control rod guide tubes (CRGT) cooling as severe accident management strategies. For this purpose, quench and cooling limit (dryout) of debris beds after their formation from fuel coolant interactions were investigated by numerical simulations using the MEWA code. LÄS MER

  5. 5. An Experimental Study on Melt Fragmentation, Oxidation and Steam Explosion during Fuel Coolant Interactions

    Författare :Louis Manickam; Weimin Ma; KTH; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; severe accident; fuel coolant interactions; melt jet breakup; debris properties; steam explosion; oxidation; high-speed visualization; Physics; Fysik;

    Sammanfattning : Nordic type boiling water reactors (BWRs) adopt reactor cavity flooding as a severe accident mitigation strategy (SAMS) to achieve core melt fragmentation and long-term cooling of decay heat generating core debris. The qualification of this SAMS needs to address two main severe accident issues: debris bed coolability and steam explosion. LÄS MER