Sökning: "Svåra haverier"

Visar resultat 1 - 5 av 9 avhandlingar innehållade orden Svåra haverier.

  1. 1. Development and Application of Uncertainty Analysis Approaches for MELCOR Simulations of Severe Accidents

    Författare :Wanhong Wang; Weimin Ma; Florian Fichot; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Severe accident; MELCOR; uncertainty analysis; Wilks’ method; Bootstrapped artificial neural network; deterministic sampling method; 95 95 tolerance limit.; Svåra haverier; MELCOR; osäkerhetsanalys; Wilks’ metod; artificiella neuronnät; deterministiska urvalsmetoder; 95 95-toleransgränser.;

    Sammanfattning : The contemporary needs in advancing safety analysis methods and the increasing stringency in light water reactor (LWR) safety in the post-Fukushima era require more advanced and systematical approaches for severe accident analyses. The best estimate plus uncertainty (BEPU) methods are among such approaches and have been widely used for deterministic safety analysis (DSA) of design basis accidents (DBAs). LÄS MER

  3. 2. CFD Study of Molten Pool Convection in a Reactor Vessel during a Severe Accident

    Författare :Boshen Bian; Walter Villanueva; Sevostian Bechta; Weimin Ma; Shuisheng He; KTH; []
    Nyckelord :Severe accident; Corium; Natural convection; Turbulence; Scalability; Direct numerical simulation DNS .; Svåra haverier; härdsmälta; naturlig konvektion; turbulens; skalbarhet; direkt numerisk simulering DNS .; Physics; Fysik;

    Sammanfattning : During severe accidents in nuclear reactors, the core and internal structures can melt down and relocate into the reactor pressure vessel (RPV) lower head (LH) forming there a stratified molten corium pool. The pool generally consists of superheated oxidic and metallic liquid layers imposing thermo-mechanical loads on the RPV wall. LÄS MER

  4. 3. Thermo-mechanical Assessment of Reactor Pressure Vessels of Light Water Reactors During Severe Accidents

    Författare :Hongdi Wang; Walter Villanueva; Sevostian Bechta; Weimin Ma; Artem Kulachenko; Michael Fitzpatrick; KTH; []
    Nyckelord :Severe accident scenario; reactor pressure vessel; in-vessel melt retention; failure analysis; finite element analysis; validations; Scenario för svåra haverier; reaktortank; in-vessel retention; feleffektsanalys; Finite Element Analyser; validering; Physics; Fysik;

    Sammanfattning : The reactor pressure vessel (RPV) is one of the crucial safety barriers designed to isolate the reactor core, safeguarding against potential radioactive releases into the environment during a severe accident. The assessment of RPV behaviour and its failure is necessary to predict the characteristics of melt release into the reactor pit and succeeding ex-vessel accident progression. LÄS MER

  5. 4. Experimental Study on Steam Explosions in Chemical Solutions and Seawater

    Författare :Yucheng Deng; Weimin Ma; Sevostian Bechta; Andrei Komlev; Renaud Meignen; KTH; []
    Nyckelord :Severe accident; fuel coolant interactions; steam explosion; chemical additives; seawater; Svåra haverier; bränsle-kylmedelsinteraktioner; ångexplosion; kemiska tillsatser; havsvatten; Kärnenergiteknik; Nuclear Engineering;

    Sammanfattning : Steam explosions may be encountered in severe accidents of light water reactors (LWRs), which are thermal detonations caused by rapid and intense vaporization of the coolant upon its direct contact with the core melt (corium). Motivated by the interest in understanding and mitigation of severe accident progression, many studies have been conducted to investigate the steam explosion phenomena during severe accidents. LÄS MER

  7. 5. 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