Post on 10-Aug-2020
Multiphase CFD Applied to Steam Condensation Phenomena in the
Pressure Suppression Pool
Marco Pellegrini
STAR Japanese Conference 2016Yokohama, Japan – June 9th 2016
N U P E C
6/10/2016 STAR Japanese Conference, Yokohama, Japan
NUCLEAR PLANTS AFFECTED BY THE 3.11 EARTHQUAKE 2
Fukushima Daiichi
Fukushima Daini
Onagawa
Operating reactor
Under inspection
~ 130 kmJMA seismic intensity
March 11th 2011
6/10/2016 STAR Japanese Conference, Yokohama, Japan
STATION BLACK OUT 3
R/B
High Pressure Alternate Cooling system
Reactor Core Isolation Cooling system
Courtesy of A. Obonai, Tohoku Electric Power CO
RCIC quencherExperiment at SIET, Italy (IAE)
T-quencherExperiment at SIET, Italy (IAE)
6/10/2016 STAR Japanese Conference, Yokohama, Japan
DIRECT CONTACT CONDENSATION IN S/C 4
R/B
MAKE-UP WATER SYSTEMSDIRECT CONTACT CONDENSATION
6.E+06
6.E+06
7.E+06
7.E+06
7.E+06
7.E+06
7.E+06
8.E+06
0 500 1000 1500 2000 2500 3000 3500
RPV pressure [M
Pa(abs)]
Time(s)
Computation by A. Buccio(IAE), 2016
Injectionpoint
~ 30 m
6/10/2016 STAR Japanese Conference, Yokohama, Japan
EULERIAN TWO-PHASE FLOW 5
∙ ∙
∙ , ∙ ∙ ∙
Instantaneous representationH
eat f
lux
Source terms ∆ ∆ Energy equation
Average representation
Hea
t flu
x
6/10/2016 NURETH-16, Hyatt Regency, Chicago
HEXAHEDRAL MESH APPLIED TO A SPHERE 6
DArea Density Magnitude of Volume
Fraction Gradient
D/16 D/32 D/64 D/128
D
Volume Fraction
6/10/2016 NURETH-16, Hyatt Regency, Chicago
HEXAHEDRAL MESH APPLIED TO A SPHERE 7
0.0%2.0%4.0%6.0%8.0%
10.0%12.0%14.0%16.0%18.0%20.0%
d/8 d/16 d/32 d/64 d/128
Erro
r [%
]
~ 9% error with large refinement
D/16 D/32 D/64 D/128
Error between the computed and theoretical area
D
6/10/2016 NURETH-16, Hyatt Regency, Chicago
POLYHEDRAL MESH APPLIED TO A SPHERE 8
D/16 D/32
0.00%
0.50%
1.00%
1.50%
2.00%
2.50%
3.00%
3.50%
d/16 d/32 d/64 d/128
Erro
r [%
]
D/8Error between the computed and theoretical area
~ 2.5% error with large refinement
6/10/2016 STAR Japanese Conference, Yokohama, Japan
DOMAIN AND MESH STRATEGIES 9
Small nozzle diameterD = 2 mm
Large nozzle diameterD = 210 mm
Mesh elements: 305,067
6/10/2016 STAR Japanese Conference, Yokohama, Japan
DOMAIN AND MESH STRATEGIES 10
Mesh elements: 405,067
D/16
Small nozzle diameter Large nozzle diameter
Mesh elements: 305,067
Small nozzle diameterD = 2 mm
Large nozzle diameterD = 210 mm
6/10/2016 STAR Japanese Conference, Yokohama, Japan
MESH SENSITIVITY - 1 11
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 20 40 60 80 100 120
Inte
rfaci
al a
rea
[cm
2 ]
Time [ms]
IFA [Mesh X 0.5]IFA [Mesh X 0.75]IFA [Mesh x1.0]IFA [Mesh x1.25]
MESH x1.25 MESH x1.0 MESH x0.750 MESH x0.5
Interfacial area
6/10/2016 STAR Japanese Conference, Yokohama, Japan
DIRECT CONTACT CONDENSATION: CHUGGING 12
Single hole pipe
In recent experiment we employed transparent pipes to visualize the bubble phenomenology during direct contact condensation
Pressure sensor
0.231 m
6/10/2016 Severe Accident Mitigation and Research Collaboration
EXPERIMENTAL EVIDENCEPo
ol te
mpe
ratu
re [°
C]
TPOOL = 57-61 °C
Steam reaching point
0.2 kg/s
water level
2.8
m
1.24
m
13
6/10/2016 STAR Japanese Conference, Yokohama, Japan
DIRECT CONTACT CONDENSATION: CHUGGING-2 14
pressure sensorMulti hole pipe
In recent experiment we employed transparent pipes to visualize the bubble phenomenology during direct contact condensation
NURETH-16, Hyatt Regency, Chicago
RAYLEIGH-TAYLOR INSTABILITY
6/10/2016
15
Psteam < Pwater
2
1i ska
Final terms for area growth
A
steam
water
Psteam
PwaterPsteam Pwater
steam
water
Accelerating flow field
Psteam
Pwater
n tt t te
6/10/2016 STAR Japanese Conference, Yokohama, Japan
IMPLEMENTATION INTO STAR-CCM+ 16Compressible 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
WATER• Incompressible – Constant properties• k-ε standard• Temperature = 62 ºCSTEAM• Compressible
velocity inletpressure outlet
adiabaticwalls
T = 106 °Cv = 11.02 m/s
Time step = Courant number limitedStopping criteria at interfacial mass transfer (1% of inlet mass flow rate)
Mesh elements: 405,067
D/16
6/10/2016 STAR Japanese Conference, Yokohama, Japan
EFFECT OF RTI MODELIZATION 18
Pressuremonitor
6/10/2016 STAR Japanese Conference, Yokohama, Japan
VOLUME FRACTION 19
Tpool = 62 ºCTpool = 62 ºC
Minimum area model Rayleigh-Taylor Instability Model
Steam flow Steam flow
6/10/2016 STAR Japanese Conference, Yokohama, Japan
20
EXP
RTI model
Tanskanen, Ph.D. Thesis 2012
No RTI model
6/10/2016 NURETH-16, Hyatt Regency, Chicago
EFFECT OF MISPREDICTION OF CHUGGING 21
Prediction of oscillating bubble creates thermal stratification in the pool
Chugging is responsible for very large mixing in the pool
6/10/2016 STAR Japanese Conference, Yokohama, Japan
SMALL NOZZLE DIAMETER: CLERX ET AL. 22
WATER• Incompressible – Constant properties• k-ε standard• Temperature = 25 ºCSTEAM• Compressible
Time step = Courant number limitedStopping criteria at interfacial mass transfer (1% of inlet mass flow rate)
Mesh elements: 405,067
D/16
6/10/2016 STAR Japanese Conference, Yokohama, Japan
VOLUME FRACTION FIELD 23
Minimum area model Rayleigh-Taylor Instability Model
Clerx et al., 20090.3 ms 0.6 ms
1.2 ms
0.9
1.5 ms 1.8 ms
Bubble implosion is less than 2 ms in the experiment at it appears immediately
6/10/2016 STAR Japanese Conference, Yokohama, Japan
CLERX ET AL. EXPERIMENT 24
0.0
1.0
2.0
3.0
4.0
5.0
6.0
0 2 4 6 8 10 12
Pene
tratio
n Le
ngth
[mm
]
Time [ms]
Clerx ExperimentBL + no RTIRTI
Minimum area model RTI ModelClerx et al., 2009
6/10/2016 STAR Japanese Conference, Yokohama, Japan
PREDICTION OF TEMPERATURE DISTRIBUTION 25
RTI Model
Clerx et al., 2009
Measured temperature field
Minimum area model
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 2 RCIC Unit 3 RCIC
6/10/2016 STAR Japanese Conference, Yokohama, Japan 27
UNIT 3UNIT 2
UNIT 1
Courtesy of S. Mizokami, TEPCO
Fukushima Daiichi power plantwhat are the conditions at this moment?