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Title: Contents

Behavior of Containment Emergency SystemsA
Review of State of the Art
Mamoru Ishii Thermal-Hydraulics and Reactor
Safety Laboratory School of Nuclear
Engineering Purdue University West Lafayette, IN
  • Introduction
  • PUMA-PCCS Separate Effect Test
  • PANDA ISP-42 Test
  • JAEAs Research Project on Horizontal Heat
    Exchanger for PCCS
  • Code Evaluations for PUMA Integral Test Including
    PCCS Performance
  • Code Capabilities
  • Summary

IntroductionPhenomenon 4 Behavior of
Containment Emergency Systems
  • Focus of Phenomenon 4
  • Natural Circulation Cooling and Heat Transfer in
    Various Containment Passive Cooling Systems under
    Accident Conditions to Remove the Energy out of
    the Containment by Natural Circulation and
    Condensation Heat Transfer
  • Typical Systems are the Tube Condensers Such As
    the PCCS in SBWR/ESBWR and External Air Cooling
    Systems in AP600/1000
  • Purpose of the Containment Safety Systems
  • To Protect the Containment under Both DBAs and
    Severe Accidents
  • To Prevent the Significant Release of Radioactive
    Materials to the Atmosphere
  • Requirements for the Containment Safety Systems
  • To Remove the Load on the Containment under
  • Most of the Load Comes from the Released Steam
    from the Reactor Primary Coolant System
  • Noncondensable Gases will Affect the Condenser

IntroductionDefinition of Phenomenon 4
Nuclear power reactor containments are equipped
with safety systems which protect the containment
integrity under various accident conditions. The
focus of Phenomenon 4 is the natural circulation
cooling and heat transfer in various containment
passive cooling systems under accident conditions
to remove the energy out of the containment by
natural circulation and condensation heat
transfer. Typical systems are the tube condensers
such as the Passive Containment Cooling System
(PCCS) and external air cooling system or
external liquid film cooling and internal
condensation of steam in the containment by
natural circulation. The major purpose of these
containment systems is to protect the containment
under both Design Basis Accidents (DBAs) and
severe accidents involving serious core damages
and to prevent the significant over
pressurization and release of radioactive
materials to the atmosphere. These systems are
required to remove the load on the containment
from the Loss of Coolant Accidents (LOCAs) and
other accidents by removing the heat but
containing the mass within the structure. Most
of the load comes from the released steam from
the primary coolant system due to the LOCA or
venting of the pressure relief valves. The major
part of the noncondensable (NC) gases consists of
the original containment atmosphere such as air
or nitrogen, however with the core damage,
hydrogen or fission gases can also be released
into the containment atmosphere. The
thermal-hydraulic phenomena of importance are
tube surface condensation with NC gases, natural
circulation of steam and NC gases, degradation of
condensation by the accumulation of NC gases and
purging of NC gases from condenser systems. The
PCCS can be vertical or horizontal tube
condensers in external water pool, exposed
condenser tube system in the containment cooled
by natural circulation water through the tubes
from the external pool or by external air
circulation and others.
  • The Final Barrier Against the Release of
    Radioactive Materials into the Environment

ESBWR Containment Figure Comes from
IntroductionPassive Safety Systems for
  • Passive Safety System for Containment Utilize
    Natural Circulation and Condensation Heat
    Transfer to Suppress the Pressure and Temperature
    of the Containment Atmosphere.
  • Examples
  • Vertical PCCS Condenser (GEs SBWR/ESBWR)
    Leonardi et al., 2006
  • Horizontal PCCS Condenser (Japan) Kondo et al.,
  • External Air Cooling System (Westinghouses
    AP600/1000) Sha et al., 2004

IntroductionTest Facilities
  • Full height, 1/400 volume ratio test facility
    simulates GEs SBWR
  • Performed separate effects and system response
  • Full height, 1/25 volume ratio test facility
    simulates GEs SBWR
  • Performed tests to check the effects of the NC
    concentration and pool inventory
  • Performed tests to investigate the PCCS start-up
    and long-term capabilities
  • Full size prototypic heat exchangers
  • Performed tests under the same thermal hydraulic
    conditions as GIRAFFE and PANDA
  • PUMA
  • 1/4 height ratio, 1/400 volume ratio test
    facility simulates GEs SBWR/ESBWR
  • Performed separate effects tests to check the
    effects of the NC concentration
  • LSTF
  • Full height, 1/48 volume ratio test facility
    simulates Westinghouse PWR
  • Horizontal Heat Exchanger Test Facility in JAEA
  • Halved full height, prototypical-scale bundle to
    represent one of four HEXs in ABWR-II
  • Single-tube test and tube bundle test have been

IntroductionContributions from the CRP
  • PUMA-PCCS Separate Effect Test
  • Purdue University, USA 3rd RCM
  • Overview on PANDA Test Facility and ISP-42 PANDA
    Tests Data Base
  • Paul Scherrer Institute, Switzerland 2nd RCM
  • JAEAs Research Project on Horizontal Heat
    Exchanger for PCCS
  • Japan Atomic Energy Agency, Japan 2nd RCM
  • Code Evaluations for PUMA Integral Test Including
    PCCS Performance
  • Purdue University, USA 2nd RCM

PUMA-PCCS Separate Effect TestObjectives
  • To study the effect of noncondensable gas
    concentration on PCCS performance using PUMA for
    three operational modes
  • Bypass Mode
  • Cyclic Venting Mode
  • Long-Term Cooling Mode
  • To study the effect of PCCS inlet (Drywell)
  • To study the effect of PCCS inlet flow rate
  • To study the effect of PCCS pool water level
  • To compare the test results with other data

PUMA-PCCS Separate Effect TestTest Facility
PUMA-PCCS Separate Effect TestPCCS Operational
  • Blowdown period before GDCS water injection to
  • Continuous flow through NC gas vent line
  • After GDCS water injection and restart boiling in
  • NC gas accumulation in the PCCS
  • Final phase of LOCA
  • Low NC gas fraction (lt 1)
  • Venting frequency approaches zero
  • (ideal case)

PUMA-PCCS Separate Effect TestTest Matrix
PUMA-PCCS Separate Effect TestEnergy Balance
  • Energy Balance
  • NC Gas Effect on Energy Balance
  • As NC gas fraction increases, ?NC gas purging
    with steam increase? increase of mass and energy
    discrepancies between PCCS inlet and outlet

PUMA-PCCS Separate Effect TestNC Effect on Heat
Transfer Coefficient
  • NC Gas Effect on Average HTC
  • As NC gas fraction increases, HTC decreases due
    to the increase of thermal resistance in the gas
  • As NC gas fraction increases, the discrepancies
    between PUMA, Kuhn and Vierows data decrease,
    because the NC venting condition is getting
    closer to a single-tube experiment (flow-through
    mode) as NC gas fraction increases.

PUMA-PCCS Separate Effect TestCombined
Correlated Test Results
  • Combined correlated data compared with PUMA-PCCS
    test data
  • Both cyclic venting and bypass with continuous
    venting follow the same trends as other research
  • PUMA and PANTHERS data fall on the same heat
    transfer coefficient trend line.

PANDA ISP-42 Test Review
JAEAs Horizontal Heat Exchanger Test Review
Code Evaluation for PUMA Integral TestPUMA
Code Evaluation for PUMA Integral TestRELAP5
Code Evaluation for PUMA Integral TestMSLB Test
Code Evaluation for PUMA Integral TestTest Data
vs. RELAP5 Simulation
Downcomer Collapsed Water Level
Code Evaluation for PUMA Integral TestTest Data
vs. RELAP5 Simulation
GDCS Loop A Injection Flow Rate
Drywell Pressure
Code Evaluation for PUMA Integral TestTest Data
vs. RELAP5 Simulation
Decay Heat Removal, Test Data
Decay Heat Removal, RELAP5 Prediction
Code Evaluation for PUMA Integral TestSummary of
Code Evaluation
  • RELAP5 was Evaluated
  • PUMA Model of RELAP5
  • Code Modeling Problems
  • Suppression Pool Condensation Model
  • 1-D Model Insufficient
  • Recirculation Pass ?? Instability
  • Artificial Flow Restriction Required
  • Suppression Pool Over Stratified
  • 1-D Model Insufficient
  • Containment Pressure Affected
  • Film Condensation Model (PCCS ICS)
  • Insufficient Modeling Accuracy
  • Effect of Noncondensable Gas not Certain
  • Containment Pressure Affected
  • Overall Performance
  • All Major Events and Trends Predicted
  • Facility and Code Scaling Capability are Good

Code CapabilitiesHeat Transfer Models in Thermal
Hydraulic System Code
  • TRACE Mode 4.0
  • Wall Vapor HTC Nusselt and empirical model
  • Wall Liquid convention HTC flow factor FChen
  • Interfacial Heat Transfer Empirical model of
    Sklover Rodivilin
  • Developed for cross-flow of gas-vapor mixtures
    on liquid jets
  • RELAP Mode 3.3 Beta
  • Default Model Saha, Nusselt
  • Alternative model UCB model

Code CapabilitiesRELAP5 Calculation Comparing
with PUMA Experimental Data
  • Default Model Under predict
  • UCB model over predict and
  • Kuhn Correlation Fluctuation
  • One of main reason of disagreement is caused by
    limitation of NC gas venting phenomenon in SP
    water in the code calculation

Code CapabilitiesCode Calculation Comparing with
PUMA Experimental Data
Table. Cooling Capability Comparison (inlet
steam flow/condensate water flow)
  • When steam with NC flow ?more discrepancy between
    experimental data and code calculation in terms
    of condensate water flow and temperatures inside
    condenser tubes It may be caused by condensation
    model limitation in calculating NC gas profile in
    the condenser tubes and venting of gas to
    suppression pool water.
  • Saturation temperatures of inlet, outlet and
    condenser tubes are over-predicted compared to
    experimental data when the NC gas exiting.
  • Code couldnt simulate cyclic venting of the NC

Code CapabilitiesCode Calculation Comparing with
  • Overall Best Results were Obtained by the Lumped
    Parameter Code SPECTRA
  • System Codes like CATHARE and RELAP5 Produced
    Acceptable Results
  • Containment Code COCOSYS Produced Acceptable
  • CATHARE and RELAP5 have the Flexibility to
    Simulate Special Components, like the PCCS
  • Strict QA Procedure for Nodalization and Input
    Deck Generation should be Followed
  • Appropriate Input Parameters should be Given in
    the Code Analysis
  • Lumped Parameter Approach should be Chosen for
    Simple Physical Situations (i.e., PCCS Start-up
  • Further Assessment of the 3-D Models and Advanced
    Modeling Features are Necessary
  • No CFD Codes Calculation has been Submitted.

Code CapabilitiesCode Calculation and
Development in JAEAs Research Project
  • Code Development
  • RELAP5 for Primary Side Calculation
  • ACE-3D was Developed for Secondary Side
  • RELAP5 and ACE-3D Coupled at the Condenser Tube
  • Calculation Successfully Predicted the
    Distribution of the Quality in the Condenser
    Tubes and the Void Fractions in the Bundle Side
  • RELAP5 MOD3 Modification
  • Heat Transfer Package was Developed for Modeling
    the Horizontal Heat Exchanger
  • Model Predicted Well the Total Heat Removal Rate
    and the Pressure Drop Across the Heat Exchanger

  • Introduction to Phenomenon 4
  • Review of the Recent Research Results on PCCS
  • PUMA Separate Effect Test (Vertical PCCS for
  • PANDA ISP-42 Test (Vertical PCCS for SBWR/ESBWR)
  • Horizontal Heat Exchanger Test in JAEA
    (Horizontal PCCS for ABWR-II)
  • Review of the Code Capabilities
  • System Code (RELAP5, TRACE)
  • System Code Coupled with 3-D CFD Code