Sökning: "Tomas Lefvert"

Hittade 4 avhandlingar innehållade orden Tomas Lefvert.

  1. 1. Sensitivity and Uncertainty Analysis of BWR Stability

    Författare :Ivan Gajev; Tomas Lefvert; Paolo Vinai; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; BWR Stability; Sensitivity; Uncertainty; Engineering physics; Teknisk fysik; SRA - Energy; SRA - Energi;

    Sammanfattning : Best Estimate codes are used for licensing, but with conservative assumptions. It is claimed that the uncertainties are covered by the conservatism of the calculation. LÄS MER

  3. 2. An experimental study on the dynamics of thin liquid films on heater surfaces

    Författare :Shengjie Gong; Tomas Lefvert; Björn Palm; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; liquid film; liquid film instability; film thickness measurement; confocal optical sensor; micro conductive probe; Physics; Fysik;

    Sammanfattning : .... LÄS MER

  4. 3. Development of Effective Algorithm for Coupled Thermal-Hydraulics – Neutron-Kinetics Analysis of Reactivity Transient

    Författare :Joanna Peltonen; Tomas Lefvert; Paolo Vinai; KTH; []
    Nyckelord :Light Water Reactor; BWR; RELAP5; PARCS; Coupling TH NK; Mapping; Spatial Refinement; Turbine Trip; Feedwater Transient; Control Rod Drop; Reactor Stability;

    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. To produce results within a reasonable computing time, the coupled codes use different spatial description of the reactor core. LÄS MER

  5. 4. The Effective Convectivity Model for Simulation and Analysis of Melt Pool Heat Transfer in a Light Water Reactor Pressure Vessel Lower Head

    Författare :Chi Thanh Tran; Tomas Lefvert; Harri Tuomisto; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; light water reactor; hypothetical severe accident; accident progression; accident scenario; core melt pool; heat transfer; turbulent natural convection; heat transfer coefficient; phase change; mushy zone; crust; lower plenum; analytical model; effective convectivity model; CFD simulation; Thermal energy engineering; Termisk energiteknik;

    Sammanfattning : Severe accidents in a Light Water Reactor (LWR) have been a subject of intense research for the last three decades. The research in this area aims to reach understanding of the inherent physical phenomena and reduce the uncertainties in their quantification, with the ultimate goal of developing models that can be applied to safety analysis of nuclear reactors, and to evaluation of the proposed accident management schemes for mitigating the consequences of severe accidents. LÄS MER