Thermal Hydraulic Studies for PFBR using PHOENICS U. PARTHA SARATHY Indira Gandhi Centre for Atomic Research Kalpakkam May 3-5 th 2004 Notes

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 U. Partha Sarathy, IGCAR 05/05/2004

PFBR Primary Circuit PUMP IHX Hot Pool CORE Inner Vessel Nuclear heat Cold Pool Grid Plate U. Partha Sarathy, IGCAR 05/05/2004

Schematic PFBR Flow Sheet Primary Circuit Secondary Circuit Steam/Water circuit U. Partha Sarathy, IGCAR 05/05/2004

HYDRAULIC ANALYSIS OF GRID PLATE- e Page

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 U. Partha Sarathy, IGCAR 05/05/2004

HYDRAULIC ANALYSIS OF GRID PLATE Modelling 2-D model in cylindrical co-ordinates (r- θ) 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 U. Partha Sarathy, IGCAR 05/05/2004

Results of Grid Plate Analysis Predicted ΔP is 4.6 m of sodium Similar to that extrapolated from 1:3 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 U. Partha Sarathy, IGCAR 05/05/2004

Thermal Analysis of Hot and Cold Pools- Title Page

Thermal Analysis of Hot and Cold Pools Objectives Inner Vessel temperature distribution Stratification In sodium pools Hot pool free surface velocity & temperature CORE U. Partha Sarathy, IGCAR 05/05/2004

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 U. Partha Sarathy, IGCAR 05/05/2004

Flow Distribution in Hot and Cold Pools Good mixing in hot and cold pools U. Partha Sarathy, IGCAR 05/05/2004

ΔT across thickness is 64 K Temperature Distribution in Inner Vessel Results Tmax in IV is 534 OC ΔT across thickness is 64 K Max hot pool free surface temperature is 572 OC Hot Pool Free Surface Temperature Distribution U. Partha Sarathy, IGCAR 05/05/2004

Flow Distribution in SG Inlet Plenum- Title Page STEAM GENERATOR INLET PLENUM

3/5 scale model of SG Inlet Plenum Schematic of PFBR SG 3/5 scale model of SG Inlet Plenum Objective:To identify flow distribution devices and reduce maximum radial velocity over tubes from FIV considerations. U. Partha Sarathy, IGCAR 05/05/2004

3/5 scale model of SG Inlet Plenum 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 U. Partha Sarathy, IGCAR 05/05/2004

Flow distribution in Inlet window region at 1430 mm from inlet =0 Flow distribution in SG Inlet Plenum – Basic Configuration 1430 mm Radial Velocity Profile along the Window with Basic Configuration U. Partha Sarathy, IGCAR 05/05/2004

Axial Velocity in the Annulus at 575 mm – Basic Configuration U. Partha Sarathy, IGCAR 05/05/2004

3/5 scale model of SG Inlet plenum with Flow distribution devices Porous plate used as a Flow distribution devices Porous plate Porous body formulation for porous plate and porous shell U. Partha Sarathy, IGCAR 05/05/2004

Axial Velocity in the Annulus at 575 mm from Inlet with Different Porous Plates U. Partha Sarathy, IGCAR 05/05/2004

U. Partha Sarathy, IGCAR 05/05/2004

Flow distribution in Inlet window region at 1430 mm from inlet 3/5 scale model of SG Inlet plenum with Flow distribution devices 1430 mm (= 0) Flow distribution in Inlet window region at 1430 mm from inlet Flow distribution in SG Inlet plenum with Flow distribution devices U. Partha Sarathy, IGCAR 05/05/2004

U. Partha Sarathy, IGCAR 05/05/2004

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 U. Partha Sarathy, IGCAR 05/05/2004

Inter-Wrapper flow Studies-Title Page

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 Inter Wrapper flow Sub-Assembly Steel hexagonal Wrapper U. Partha Sarathy, IGCAR 05/05/2004

Sodium Flow in Primary Circuit DHX CORE U. Partha Sarathy, IGCAR 05/05/2004

CFD model for IWS and Hot and Cold Pools 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. CFD model for IWS and Hot and Cold Pools U. Partha Sarathy, IGCAR 05/05/2004

Schematic of the SA Computational Model Schematic of Fuel SA U. Partha Sarathy, IGCAR 05/05/2004

Exchange of Results between 1-D and 2-D PHOENICS Models for Boundary Conditions U. Partha Sarathy, IGCAR 05/05/2004

Flow Chart for Coupled 1D Code – PHOENICS code Calculations U. Partha Sarathy, IGCAR 05/05/2004

Flow Distribution in Hot m/s m/s Flow Distribution in Hot and Cold pools Temperature Contours in Hot and Cold pools U. Partha Sarathy, IGCAR 05/05/2004

Temperature and Velocity Distribution in Inter- Wrapper Space 425 415 555 405 395 OC m/s m/s Temperature and Velocity Distribution in Inter- Wrapper Space U. Partha Sarathy, IGCAR 05/05/2004

Temperature Distribution in IV 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 U. Partha Sarathy, IGCAR 05/05/2004

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 U. Partha Sarathy, IGCAR 05/05/2004

Transient Evolution of Temperatures in Hot and Cold Pools Results Transient Evolution of Temperatures in Hot and Cold Pools

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