Thermal Hydraulic Studies for PFBR using PHOENICS

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Thermal Hydraulic Studies for PFBR using PHOENICS

• U. PARTHA SARATHY
• Indira Gandhi Centre for Atomic Research
• Kalpakkam
• May 3-5 th 2004

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PROTOTYPE FAST BREEDER REACTOR(PFBR)

• Power - 500 MWe, 1250 MWth
• Fuel Mixture of UO2 (79 ) and PuO2 (21 )
• Coolant Sodium (liquid metal) in Pry and Secy
  Circuits
• Water in Tertiary Circuit
• High Temperatures
• High Velocities
• Problems
• High temperatures leading to creep, fatigue
  damage
• Flow induced vibrations
• Thermal striping
• Gas entrainment

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PFBR Primary Circuit
Inner Vessel
PUMP
IHX
Hot Pool
Nuclear heat
CORE
Cold Pool
Grid Plate
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Schematic PFBR Flow Sheet

• Primary Circuit

• Secondary Circuit

• Steam/Water circuit

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HYDRAULIC ANALYSIS OFGRID PLATE- e Page

• HYDRAULIC ANALYSIS OF
• GRID PLATE

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HYDRAULIC ANALYSIS OF GRID PLATE

• Consists of 1758 sleeves
• Receives flow from four pipes
• Distributes flow to various subassemblies
• Objectives
• Flow and pressure distribution
• Pressure drop in GP
• Velocity over sleeves

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HYDRAULIC ANALYSIS OF GRID PLATE

• Modelling
• 2-D model in cylindrical co-ordinates (r- ?)
• Sleeves modeled through porosity in radial and
  circumferential directions (Porous body
  formulation)
• Inlet as Velocity BC
• Outlets as mass sinks
• Pressure drop due to sleeves modeled through
  Zukauskas correlation
• Addition of resistance terms in the momentum
  equation using ground subroutine.
• K-E Turbulence model

Schematic of Grid Plate
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Results of Grid Plate Analysis

• Results
• Predicted ?P is 4.6 m of sodium
• Similar to that extrapolated from 13 scale air
  experiments.
• Pressure contours are concentric uniform flow
  through fuel SA
• Maximum cross flow velocity is 8.5 m/s

Flow Distribution in Grid Plate
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Thermal Analysis of Hot and Cold Pools- Title
Page

• Thermal Analysis of
• Hot and Cold Pools

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Thermal Analysis of Hot and Cold Pools

• Objectives
• Inner Vessel temperature distribution
• Stratification In sodium pools
• Hot pool free surface velocity temperature

CORE
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CFD Model and Boundary Conditions

• Modelling
• 2-D model in cylindrical co-ordinates (r-z)
• Core is modeled as a block
• Porous body approximation for immersed components
  IHX, Pump
• Mass sink at IHX PUMP inlets
• Velocity BC at IHX and Core outlets
• Conjugate thermal hydraulic analysis of hot
  cold pools including IV
• K-E Turbulence model

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Flow Distribution in Hot and Cold Pools

• Good mixing in hot and cold pools

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• Results
• Tmax in IV is 534 OC
• ?T across thickness is 64 K
• Max hot pool free surface temperature is 572 OC

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Flow Distribution in SG Inlet Plenum- Title Page

• FLOW DISTRIBUTION IN
• STEAM GENERATOR INLET PLENUM

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Schematic of PFBR SG
3/5 scale model of SG Inlet Plenum

• ObjectiveTo identify flow distribution devices
  and reduce maximum radial velocity over tubes
  from FIV considerations.

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• Modelling
• 3/5 scale model
• 3-D cylindrical coordinates
• 180 O symmetric model
• K-E turbulence model
• Inlet as velocity BC

3/5 scale model of SG Inlet Plenum
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• 1430 mm

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Porous plate

• Porous body formulation for porous plate and
  porous shell

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Axial Velocity in the Annulus at 575 mm from
Inlet with Different Porous Plates
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• 1430 mm

Flow distribution in SG Inlet plenum with Flow
distribution devices
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• RESULTS
• Combination of graded porous plate and porous
  shell render as uniform flow both axially and
  circumferentially.
• The distributions of porosity in the plate and
  shell have been identified.
• Maximum radial velocity is 0.75 m/s (average is
  0.45 m/s) whereas the same is 3 m/s in basic
  configuration

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Inter-Wrapper flow Studies-Title Page

• Inter-Wrapper flow
• Studies

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Inter-Wrapper flow Studies - Steady State

• Objectives
• Effect of IWF on SA clad hotspot
• Flow distribution in IWS
• To develop a model for studying various design
  basis events which will give detailed temperature
  distribution in hot and cold pools

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Sodium Flow in Primary Circuit
CORE
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• Modeling
• 2-D cylindrical coordinates (r-z)
• Inlets as velocity BC
• Outlets as mass sink
• Porous body formulation for core and other
  immersed structures
• Coupling with 1-D model for neutronics, heat
  transfer calculations in core, IHX, DHX etc.

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Schematic of Fuel SA
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Flow Chart for Coupled 1D Code PHOENICS code
Calculations
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m/s
m/s
Temperature Contours in Hot and Cold pools
Flow Distribution in Hot and Cold pools
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425
415
555
405
395 OC
m/s
m/s
Temperature and Velocity Distribution in
Inter-Wrapper Space
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• Results
• SSA outlet temperature increases by about 2 K
• Total heat transferred to IWS is 370 kW
• Axial temperature gradient of hot/cold interface
  is 150 K/m

Temperature Distribution in IV
Temperature Distribution in MV
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Inter-Wrapper flow Studies - Transient Analysis
(under progress)

• Station blackout incident
• All pumps trip
• Primary circuit flow coasts down
• Secondary circuits not available
• Reactor trips only at 2.5 s
• Temperature inside SA goes up
• Good amount of heat is taken away by the IWF

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Results
Transient Evolution of Temperatures in Hot and
Cold Pools

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• Thank You