Multiphase CFD Applied to Steam Condensation Phenomena in the - PowerPoint PPT Presentation

Multiphase CFD Applied to Steam Condensation Phenomena in the Pressure Suppression Pool Marco Pellegrini N U P E C STAR Japanese Conference 2016 Yokohama, Japan – June 9 th 2016

NUCLEAR PLANTS AFFECTED BY THE 3.11 EARTHQUAKE 2 March 11 th 2011 Operating reactor Under inspection Onagawa JMA seismic intensity ~ 130 km Fukushima Daiichi Fukushima Daini 6/10/2016 STAR Japanese Conference, Yokohama, Japan

STATION BLACK OUT 3 High Pressure Alternate Cooling system R/B Courtesy of A. Obonai, Tohoku Electric Power CO Reactor Core Isolation Cooling system T-quencher RCIC quencher Experiment at SIET, Italy (IAE) Experiment at SIET, Italy (IAE) 6/10/2016 STAR Japanese Conference, Yokohama, Japan

DIRECT CONTACT CONDENSATION IN S/C 4 8.E+06 MAKE-UP WATER SYSTEMS 7.E+06 DIRECT CONTACT CONDENSATION RPV pressure [MPa(abs)] 7.E+06 R/B 7.E+06 7.E+06 7.E+06 6.E+06 6.E+06 0 500 1000 1500 2000 2500 3000 3500 Time(s) Injection point Computation by A. Buccio ~ 30 m (IAE), 2016 6/10/2016 STAR Japanese Conference, Yokohama, Japan

EULERIAN TWO-PHASE FLOW 5 Instantaneous representation Average representation Heat flux Heat flux Source terms Energy equation �� ���� � � � � ∆�∆� ��� � �� � � � � � � � � ∙ � � � � � � � � � � � � � ∙ � � � � � � ���� � � � � � � � ∙ � � � � � � � ∙ � � � ���,� �� � � � ∙ � � ∙ � � � � � � �� � � � �� � � �� �� � 6/10/2016 STAR Japanese Conference, Yokohama, Japan

HEXAHEDRAL MESH APPLIED TO A SPHERE 6 D D/16 D/32 D/64 D/128 Volume Fraction D Area Density Magnitude of Volume � � Fraction Gradient 6/10/2016 NURETH-16, Hyatt Regency, Chicago

HEXAHEDRAL MESH APPLIED TO A SPHERE 7 D D/16 D/32 D/64 D/128 Error between the computed and theoretical area 20.0% 18.0% 16.0% 14.0% Error [%] 12.0% ~ 9% error with 10.0% 8.0% large refinement 6.0% 4.0% 2.0% 0.0% d/8 d/16 d/32 d/64 d/128 6/10/2016 NURETH-16, Hyatt Regency, Chicago

POLYHEDRAL MESH APPLIED TO A SPHERE 8 D/8 D/16 D/32 Error between the computed and theoretical area 3.50% 3.00% ~ 2.5% error with 2.50% large refinement Error [%] 2.00% 1.50% 1.00% 0.50% 0.00% d/16 d/32 d/64 d/128 6/10/2016 NURETH-16, Hyatt Regency, Chicago

DOMAIN AND MESH STRATEGIES 9 Small nozzle diameter Large nozzle diameter D = 2 mm D = 210 mm Mesh elements: 305,067 6/10/2016 STAR Japanese Conference, Yokohama, Japan

DOMAIN AND MESH STRATEGIES 10 Small nozzle diameter Small nozzle diameter Large nozzle diameter Large nozzle diameter D = 2 mm D = 210 mm Mesh elements: D/16 305,067 Mesh elements: 405,067 6/10/2016 STAR Japanese Conference, Yokohama, Japan

MESH SENSITIVITY - 1 11 MESH x0.750 MESH x0.5 MESH x1.25 MESH x1.0 0.7 IFA [Mesh X 0.5] IFA [Mesh X 0.75] IFA [Mesh x1.0] 0.6 IFA [Mesh x1.25] Interfacial area [cm 2 ] 0.5 Interfacial area 0.4 0.3 � � 0.2 0.1 0.0 0 20 40 60 80 100 120 Time [ms] 6/10/2016 STAR Japanese Conference, Yokohama, Japan

DIRECT CONTACT CONDENSATION: CHUGGING 12 Pressure sensor Single hole pipe In recent experiment we employed transparent pipes to visualize the bubble phenomenology during direct contact condensation 6/10/2016 STAR Japanese Conference, Yokohama, Japan

EXPERIMENTAL EVIDENCE 13 0.2 kg/s T POOL = 57-61 °C water level Pool temperature [°C] Steam reaching point 2.8 m 1.24 m 0.231 m 6/10/2016 Severe Accident Mitigation and Research Collaboration

DIRECT CONTACT CONDENSATION: CHUGGING-2 14 pressure sensor Multi hole pipe In recent experiment we employed transparent pipes to visualize the bubble phenomenology during direct contact condensation 6/10/2016 STAR Japanese Conference, Yokohama, Japan

RAYLEIGH-TAYLOR INSTABILITY 15 Accelerating flow field steam steam P steam P stea m A water P wate water P water r P steam P water P steam < P water Final terms for area growth     n t t e  t t 2    k     1   a  i s   6/10/2016 NURETH-16, Hyatt Regency, Chicago

IMPLEMENTATION INTO STAR-CCM+ 16 Compressible steam flow Compressible steam flow Record amplitude length at previous time step 6/10/2016 STAR Japanese Conference, Yokohama, Japan

LARGE NOZZLE DIAMETER: POOLEX 17 pressure velocity inlet outlet T = 106 °C v = 11.02 m/s adiabatic walls D/16 WATER • Incompressible – Constant properties • k-ε standard • Temperature = 62 ºC STEAM • Compressible Time step = Courant number limited Mesh elements: 405,067 Stopping criteria at interfacial mass transfer (1% of inlet mass flow rate) 6/10/2016 STAR Japanese Conference, Yokohama, Japan

EFFECT OF RTI MODELIZATION 18 Pressure monitor 6/10/2016 STAR Japanese Conference, Yokohama, Japan

VOLUME FRACTION 19 Rayleigh-Taylor Instability Model Minimum area model Steam flow Steam flow T pool = 62 ºC T pool = 62 ºC 6/10/2016 STAR Japanese Conference, Yokohama, Japan

20 Tanskanen, Ph.D. Thesis 2012 EXP RTI model No RTI model 6/10/2016 STAR Japanese Conference, Yokohama, Japan

EFFECT OF MISPREDICTION OF CHUGGING 21 Prediction of oscillating bubble creates Chugging is responsible for very large thermal stratification in the pool mixing in the pool 6/10/2016 NURETH-16, Hyatt Regency, Chicago

SMALL NOZZLE DIAMETER: CLERX ET AL. 22 D/16 WATER • Incompressible – Constant properties • k-ε standard • Temperature = 25 ºC STEAM • Compressible Time step = Courant number limited Mesh elements: 405,067 Stopping criteria at interfacial mass transfer (1% of inlet mass flow rate) 6/10/2016 STAR Japanese Conference, Yokohama, Japan

VOLUME FRACTION FIELD 23 0.3 ms 0.6 ms 0.9 Clerx et al., 2009 1.2 ms 1.5 ms 1.8 ms Bubble implosion is less than 2 ms in the experiment at it appears immediately Rayleigh-Taylor Instability Model Minimum area model 6/10/2016 STAR Japanese Conference, Yokohama, Japan

CLERX ET AL. EXPERIMENT 24 RTI Model Minimum area model Clerx et al., 2009 6.0 Clerx Experiment BL + no RTI 5.0 RTI Penetration Length [mm] 4.0 3.0 2.0 1.0 0.0 0 2 4 6 8 10 12 Time [ms] 6/10/2016 STAR Japanese Conference, Yokohama, Japan

PREDICTION OF TEMPERATURE DISTRIBUTION 25 Minimum area model Measured temperature field RTI Model Clerx et al., 2009 6/10/2016 STAR Japanese Conference, Yokohama, Japan

THE CHALLENGE OF ACCIDENT COMPUTATION 26 R/B R/B R/B accident time scale [ days ] Unit 1 vent pipes Unit 3 RCIC Unit 2 RCIC 6/10/2016 STAR Japanese Conference, Yokohama, Japan

Fukushima Daiichi power plant what are the conditions at this moment? UNIT 1 UNIT 2 UNIT 3 Courtesy of S. Mizokami, TEPCO 6/10/2016 STAR Japanese Conference, Yokohama, Japan 27