Laboratory of Thermal Hydraulics. General Overview

Transcription

1 Visit of Nuclear Master Students Laboratory of Thermal Hydraulics General Overview Horst-Michael Prasser December 04, 2009 Paul Scherrer Institut

2 Main Goals Development of analytical and experimental methods to - Predict the thermal fluid-dynamic behavior including the transport of radionuclides and aerosols in safety related processes on nuclear power plants - Replace empirical modeling by fundamental physics - Increase accuracy and reliability of predictions, reduce safety margins and conservative assumptions Application of expertise and tools developed in thermal-hydraulics, aerosol physics and iodine chemistry to resolve critical safety issues of current and future nuclear reactors Support to utilities and vendors, safety authorities and other PSI projects by applying the developed methods

3 Research Strategy 3D fluid dynamics (CFD) Multi-scale modeling Multiphase flows Unity of Theory & Experiment Main target Liquid vapor flows Iodine and aerosol transport LWR problems Theory Model Simulation Experiment Instrumentation Validation

4 Reactor Pressure Vessl PANDA Multi-purpose Test Facility Laboratory for Thermalhydraulics Condenser Pools 25m PANDA designed for LWR thermal-hydraulic investigations: Integral system behavior at large scale Typical phenomena in multi-compartment geometries Best containment test facility world-wide Major application areas of PANDA: Integral containment system tests (e.g. passive decay heat removal) Primary system tests (e.g. natural circulation stability) Component tests (e.g. condenser performance) Separate effect tests (e.g. steam/gas distribution and basic flow structures) Development of passive safety systems for Gen-III VB Condenser (for DW) Modular structure of PANDA Drywell Wetwell Suppression Pool GDCS Pool Condenser (for RPV) Drywell Wetwell Suppression Pool 0 m VB

5 OECD-SETH Project: Generic PANDA Tests Background of PANDA Test Program: Gas mixing/stratification inside containments is a key issue for accident analyses High resolution data for 3D code validation are missing Objectives: Investigation of steam/air/helium mixing and basic flow structures in large multi-compartment geometries Testing philosophy: Well controlled test initial and boundary conditions Use of advanced measurement techniques (MS, PIV) PANDA Near Wall Plume / Jet Tests DW1 Steam injection Steam/gas vent DW2 Measurement locations: Temperatures/ Concentrations PIV measurement area Projects: Size measurements of seed particles CFD modeling of containment flows Evaluation of novel measuring data

6 Industry Contract AREVA Pre-test analysis of passive safety systems test INKA (Karlstein) GOTHIC, RELAP Instrumentation of INKA with gas composition measuring system from PANDA successfully accomplished Intentions for future extension PhD proposal on condensation modeling in emergency condenser External reviews (e.g. INKA scaling) Code validation (TH system codes) INKA Test Facility 1:24 SWR1000 passive systems model

7 ARTIST: AeRosol Trapping In a Steam GeneraTor: Facility pictures

8 ARTIST: Separator & Dryer for Droplet Tests PDA Laser beams More Info: Presentation T. Lind

9 CFD ACTIVITIES IN Primary Circuit Mixing in an RPV Large Eddy Simulations Turbulent mixing in T-junction MEGAPIE Project: Target optimization 382 o C 230 Containment analysis Species concentration t = 5.0 Interface Tracking Thermal stresses 344 o C t = 2.5 Using 244 t = 0.0 Level Set Technique 73.7 MPa 0.7

10 LES + Surface tracing Aims PSI-boil Fundamental Two-Phase Flow Modelling Mixing phenomena in single phase flows Cyclical thermal loads on structures Flow boiling Modeling of Boiling Crisis Experimental validation Pressurized loop in development Projects: LES simulations of flow boiling Design of new test loop Laboratory for Thermalhydraulics

11 Coalescence of bubbles due to the wake effect PSI-boil on 180 processors Calculation time 5 h LES + surface tracking (level set technique)

12 Multi-disperse bubbly flow PSI-boil on 180 processors Calculation time 5 h LES + surface tracking (level set technique)

13 Experiment for Turbulent Mixing (EXTREM) Projects: Experiments on turbulent mixing structures at high density gradients Analysis of conjugate heat transfer at the wall

14 ρ up <<ρ down ρ up <ρ down ρ up =ρ down ρ up >ρ down ρ up >>ρ down Density influence on turbulent mixing

15 WMS x/d = Isothermal case Display frequency 1 khz

16 LES calculations (FLUENT) Fluent 6.3 only hexahedral cells Smagorinsky Subgrid Scale (SGS) Smag. constant = 0.06 (wall-bounded flows) Wall-adaptation (WALE) for reduction of SGS eddy viscosity in near-wall regions Inlet turbulence 10% Time step: 0.1 ms Bojan Niceno 6D

17 Mesh sensor vs. LES (FLUENT) Laboratory for Thermalhydraulics Sensor 1 LES / Fluent Isothermal case: L/D = 1 Main flow: 0.5 m/s Side branch: 0.5 m/s transient comparison

18 Mesh sensor vs. LES (FLUENT) Laboratory for Thermalhydraulics Sensor 1 LES / Fluent Projects: CFD validation of turbulent mixing models

19 Adiabatic bundle experiments with mesh sensors + Steam Generator Tube Bundle Projects: Participation in the experiments and analyses

20 Adiabatic bundle experiments with mesh sensors Implementation of wire-mesh sensors in the bundle Resolution of the wiremesh sensors 2 mm Rate: 2.5 khz Bundle scale: ~2.5:1 Start operation. End 2009

21 Local instantaneous void fraction distributions by wiremesh sensors Vertical Test Channel 2½D + t

22 2Ph flow in BWR fuel assemblies Laboratory for Thermalhydraulics Gas and liquid circulated He, Air, C 4 F 8 2 m test section Entrance length 1.5 m Water injection as film Double Subchannel at ETHZ

23 Time resolved Film Thickness Laboratory for Thermalhydraulics Test of functional spacer grids Superficial velocities 40 m/s air 0.3 m/s water at ETHZ

24 Progress of ultrafast X-ray tomography in Rossendorf Full angle ultra fast electron beam CT scanner ROFEX at FZD frames / second with better than 1 mm resolution Applicable to steam-water flows up to 7 MPa (D = 50 mm) What about neutrons? Projects: Development of neutron tomography, Monte-Carlo analyses X-rays neutrons

25 Feasibility of fast neutron tomography Laboratory for Thermalhydraulics Challenges: First step: Scannable source feasible only with fast neutrons Efficiency of detectors for fast neutrons (student project: Patrick Vogler) Pulsed or scanning neutron sources Slow tomograph with fast neutrons: demonstrate components Future co-operation: University of California, Berkeley Ka-Ngo Leung Neutron production rate with D-D-reaction: n/s (no Tritium necessary)

26 Feasibility Fast Neutron Tomography (TwoFast) "TwoFast" = fast neutrons x fast imaging Goal: Repeat time resolution of ultra-fast X-ray tomography (FZ Rossendorf) with fast neutrons perspective alternative for fuel rod bundle experiments First step: Feasibility study with a plasma neutron source (d-d reaction) 2.45 MeV neutrons 10 8 neutrons 1/s Pulsed operation Aim: Detector development Design studies X-ray tomography of FZ Rossendorf Installation at PSI: Autumn 2009

27 Fusion neutron source Burning test plasma

28 Research links between ETH Zurich and -PSI US transducers SETH-2 / PANDA Dynamic film flows in BWR fuel assemblies Gas composition and velocity instrumentation development Complementary small-scale studies PhD Martin Ritterath Air ingress studies for Gas-cooled High-Temperature Reactors Fundamental mixing studies (PhD student: Jürren Fokken) Experiments in fuel assembly sub-channel models (PhD Manuel Damsohn) M. Ritterath + TU Nizhny Novgorod Flow Boiling modeling Micro-sensor development, micro lithographic methods to produce sensor structures in glass substrate (PhD Sudent: Paolo D Aleo) Neutron imaging Experiments on efficient fast-neutron detection (Master project, Dupont) Projects (e.g.): Temperature mesh sensor Experiments at PANDALINO (at ETHZ) Perfection of the dynamic liquid film sensor Pandalino at ETHZ