Sökning: "Ma Weimin"

Visar resultat 6 - 10 av 14 avhandlingar innehållade orden Ma Weimin.

1. 6. 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

3. 7. 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

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

   Författare :Louis Manickam; Weimin Ma; KTH; []
   Nyckelord :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

5. 9. Effective Spatial Mapping for Coupled Code Analysis of Thermal–Hydraulics/Neutron–Kinetics of Boiling Water Reactors

   Författare :Joanna Peltonen; Weimin Ma; Maria Avramova; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Boiling Water Reactor; RELAP5; TRACE; PARCS; Coupled TH NK analysis; Spatial Mapping; Turbine Trip; Feedwater Transient; Control Rod Drop; Reactor Stability; Hierarchical Clustering; kokvattenreaktor; reaktoranalys; RELAP5; TRACE; PARCS; TH NK analys; turbin tripp; matarvatten transient; fallande styrstav; reaktor stabilitet; hierarkisk klustringsmetodik; SRA - Energy; SRA - Energi;

   Sammanfattning : Analyses of nuclear reactor safety have increasingly required coupling of full three dimensional neutron kinetics (NK) core models with system transient thermal–hydraulics (TH) codes.  In order to produce results within a reasonable computing time, the coupled codes use two different spatial description of the reactor core. LÄS MER

7. 10. On Fuel Coolant Interactions and Debris Coolability in Light Water Reactors

   Författare :Sachin Thakre; Weimin Ma; Florian Fichot; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; severe accident; fuel-coolant interactions; melt jet fragmentation; steam explosion; debris bed coolability; uncertainty analysis; Energiteknik; Energy Technology;

   Sammanfattning : During the case of a hypothetical severe accident in a light water reactor, core damage may occur and molten fuel may interact with water resulting in explosive interactions. A Fuel-Coolant Interactions (FCI) consists of many complex phenomena whose characteristics determine the energetics of the interactions. LÄS MER