Numerical and Experimental Investigations of the Emergency Condenser

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Numerical and Experimental Investigations of the
Emergency Condenser
E. Krepper, M. Beyer, H. Carl, H.-M.
Prasser COORDINATED RESEARCH PROJECT ON NATURAL
CIRCULATION PHENOMENA, MODELLING AND RELIABILITY
OF PASSIVE SAFETY SYSTEMS THAT UTILIZE NATURAL
CIRCULATION 29.08. 02.09.2005

• Operation schemes of the emergency condenser and
  investigated Phenomena
• NOKO experiments
• TOPFLOW experiments

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SWR-1000 safety concept
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Operation scheme of an BWR - emergency condenser
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Which amount of power can be transferred under
certain thermalhydraulic conditions?

• Investigated phenomena
• Condensation in horizontal tubes
• Phenomena on the secondary side
• Temperature stratification
• with higher heat fluxes Boiling, condensation
• Pressure increase in the pool
• CFD-task Common turbulence models consider
  turbulent viscosity as scalar, but here
  anisotropy

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NOKO-test facility

• Operated in FZ-Jülich 1995-2000
• Main subject
• Investigation of the heat transfer capability of
  an emergency condenser by condensation in
  horizontal tubes
• A. Schaffrath E.F. Hicken H. Jaegers, H.-M.
  Prasser Experimental and Analytical
  Investigation of the Operation Mode of the
  Emergency Condenser of the SWR1000 Nuclear
  Technology 126 (1999), May 1999, p. 123-142
• Additional experiments 1989-2000
• Investigation of the heating up processes on the
  secondary side
• E. Krepper, E.-F. Hicken, H. Jaegers
  Investigation of Natural Convection in Large
  Pools International Journal of Heat and Fluid
  Flow Vol. 23 (2002) pp. 359-365
• E. Krepper, A. Schaffrath, A. Aszodi Numerical
  Simulation of the Emergency Condenser of the
  SWR-1000 Nuclear Science and Engineering 135
  (2000), 267279

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Schematic view of the NOKO-test facility
Primary pressure 1 MPa transferred power ca. 0.6
MW
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Heating up experiment

• Thermocouples on the secondary side were arranged
  in 5 planes
• Level in the core simulator was adjusted, that
  only the upper three tubes of the condenser were
  filled with steam

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Arrangement of the thermocouples in the measuring
plane
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Measured temperature distributionsafter a
heating up time of about 2000 s
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Measured Results - Conclusions

• All 5 measuring planes show in principle the
  same temperature distribution
• 2D approach by modelling of only one plane is
  justified

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CFX calculations
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Measured and calculated temperature courses
centre line
side line
Meas.
Calc.
Tav mean pool temperature
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Safety related importance of the temperature
stratification

• Saturation temperature at the upper surface is
  earlier reached than with ideal temperature
  mixing
• At the surface Boiling after ca. 2000 s
• Tav Boiling after ca. 8000 s
• More steam in the containment generated
• Investigation of measures, to avoid temperature
  startification

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Insertion of two straight vertical guide plates
to ensure, that the whole part of the water
volume takes place in the heating up
t 100 s
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t 200 s
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t 400 s
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Investigation of measures, to avoid the
temperature stratification

• After about 1000 s the circulation has slowed
  down.
• The reason is a large vortex in the upper part
  between the plates.
• The guide plates have not the desired effect.
  Further optimisation is necessary.

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TOPFLOW Multipurpose Transient Two Phase Flow
Test Facility
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TOPFLOW-Building
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Heater

• Electrical heat generation up to 4 MW
• up to 2 kg/sec steam

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Cooler
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TOPFLOW Multipurpose Transient Two Phase Flow
Test Facility
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Condenser Tank
Steam inlet
Condensate outlet
Parameters Maximum Pressure 1 MPa Maximum
temperature 180 C Length 6,4 m Outer
diameter 2 m Wall thickness 50
mm Volume 17,7 m³ Weight 40 t
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Arrangement of thermocouples in the tank
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Condensing tubes
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Arrangement of thermocouples in the tank
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Experimental procedure

• Injecting steam in the bundle at a certain
  pressure
• Secondary side at normal conditions (0.1 Mpa)
• Heating up the tank by removing of maximum
  condensate
• Determination of the characteristic curve of the
  bundle by removing determined amounts of
  condensate

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Injected steam and removed condensate (Test at
6.5 Mpa)
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Time development of the Temperature in the tank
(1.0 Mpa)
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Time development of the Temperature in the tank
(5.0 Mpa)
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Time development of the Temperature in the
tank(6.5 Mpa)
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Heating up of the secondary side (6.5 Mpa)
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Heating up of the secondary side (6.5 Mpa)
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Characteristic curves of the bundle