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Washington DC Short Course

Thermal-hydraulics of Nuclear Systems


The Marriott Residence Inn, Bethesda
Washington, D.C.
September 25 - 29, 2017

Hosted by:
The Energy Institutes
City College New York and University of Wisconsin, Madison

Schedule & Contents of Lectures

Part I.   Bases

Monday, September 25 (9-12:30 and 2-5:30)

  1. Introduction: M.L. Corradini. Nuclear system descriptions, current LWR Gen III and advanced Gen IV designs. Significant flow phenomena with examples. Operational and safety implications. Current thermal-hydraulics issues. Layout of lectures, where topics addressed.

  2. Introduction to Nuclear Fluid Mechanics and Heat Transfer: S. Banerjee. Fundamentals of fluid mechanics and heat transfer as applied to nuclear systems. Conservation equations and constitutive models. Ensemble, volume and cross-sectional area averaging. Simple closure relationships for friction, drag and heat transfer. Single-phase flow applications, steady-state and transients; single-phase anticipated operational transients. Multiphase flows, definitions and phenomen in nuclear systems. Introduction to flow regimes (movie).

  3. Engineering Models for Two-Phase Flow: G. Yadigaroglu. Engineering approaches to two-phase flow predictions in nuclear systems. Flow regime correlations. Correlations for frictional pressure gradient and void fraction. Countercurrent flow limitations and correlations.

  4. Phenomenological Models for Multiphase Flow: G.F. Hewitt. Vertical flows: Phenomenological models for bubble flow, bubble/slug transition. Slug flow and the slug churn transition. Churn flow. Churn/annular transition. Annular flow. Wispy annular flow. Phenomenological models for horizontal flows: Stratified flow. Stratified/slug transition. Slug flow. Stratified/slug/annular transition. Annular flow in nuclear systems.

  5. Tuesday, September 26 (9-12:30 and 2-5:30)

  6. Light Water Reactor Phenomena: G. Yadigaroglu. Normal operation thermalhydraulics, anticipated operational occurrences, loss-of-coolant accidents, and their simulation; uncertainty evaluation. In-vessel accident phenomenology; modelling of core cooling. Passive emergency core and containment cooling.

  7. Two-phase heat transfer: G.F. Hewitt. Single component systems; heat transfer regimes, heat transfer in slug flow (equilibrium, non-equilibrium); heat transfer in annular flow, correlations, mechanisms, models (overall, detailed, effect of nucleate boiling). Dryout (critical) heat flux; low quality (bubbly) and high quality (annular) flows. Condensation; similarities and differences to evaporation. Non-condensible effects.

  8. Dryout in simple and complex geometries: G. F. Hewitt. Dryout in tubular and annular geometries. Core configurations in conventional and advanced PWR's and BWR's. Critical heat flux in rod bundle geometries; prediction methods (global models, sub-channel methods, phenomenological models); effects of non-uniform flux distribution; grid design for enhancement.

  9. Advanced Light Water Reactor Concepts and Phenomena: M. L. Corradini. Review of advanced LWR concepts for near-term and Generation IV reactor development. Two-phase phenomena in passive safety systems (natural circulation, condensation, critical flow).

  10. Wednesday, September 27 (9-12:30 and 2-5:30)

  11. Thermal non-equilibrium flows: G. Yadigaroglu. Importance of departures from mechanical and thermal equilibrium in nuclear systems. Computation of non-equilibrium flows. Subcooled boiling. Post-dryout heat transfer; 3D effects.

  12. Multifield models: S. Banerjee. The need for multi-field models. Interpenetrating continua and Lagrangian-Eulerian approaches. Closure requirements. One-dimensional form-structure, strengths and weaknesses. Multi-dimensional aspects: applicability and limitations.

  13. Closure laws in nuclear systems codes: S. Bajorek. Development and validation of closure laws dependent on flow regime. Hydrodynamic and heat transfer closure relationships in system codes and their limitations. Predicting choked flow, stratified flow, CCFL.

  14. Numerical methods: S. Banerjee. Introduction to finite differences. Initial and boundary conditions. Method of characteristics. Finite difference methods. Stability. Explicit and implicit methods used in computer codes.

  15. Part II.   Applications

    Thursday, September 28 (9-12:30 and 2-5:30)

  16. Two-Phase Instabilities: G. Yadigaroglu. Instabilities of the liquid-gas interface; applications to jets, particles, etc. Two-phase system instabilities; fundamentals, mechanism. Computational tools, stability maps. BWR stability.

  17. Nuclear Systems Codes: S. Bajorek. Modeling of nuclear systems at the component level, modelling approach and nodalization approach. Review of major system code models, such as TRACE, COBRA/TRAC, VIPER, TRACE, TRACG.

  18. Single Phase Models and Sub-channel Analysis: S. Bilbao. Sub-channel analysis modelling approach, transverse momentum transport, grid spacer and wire-wrap effects, multi-channel flow analyses and core-wide analysis approaches.

  19. CFD for Nuclear Systems: C. Boyd. Overview of available tools for CFD. Solvers, models and algorithms. A selection of examples illustrating some of the challenges and advanced models used in the analyses of nuclear single- and multi-phase flow problems.

  20. Friday, September 29 (8:30-12:30)

  21. Coupled Neutronics and Thermal-Hydraulics: T. Downar. The basic couplings (diffusion eqs and the effects of void fraction and Doppler). Normal and accident situations where the coupling becomes important: ATWS, boron mixing, stability of BWRs, extended operating domain operations.

  22. LWR Beyond Design Basis Safety Analyses: M.L. Corradini. Multiphase phenomena during severe accidents: vapor explosions, molten core quenching and coolability, etc. Severe accident modeling with system analyses and simulation.

  23. Part III.   CMFD with Commercial Codes (Tentative)

    Friday, September 29 (1:30-3:30)

    Simulation of multiphase flow in nuclear systems: RELAP7 Simulation Tools

    Simulating multiphase flows in transients and accidents: MELCOR Systems Code

    Simulation multiphase flow: STAR-CCM+
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