CORPUS : A MULTIPHYSICSSALOME APPLICATION FOR REACTOR...

CORPUS : A MULTIPHYSICS SALOME

APPLICATION FOR REACTOR

MULTIPHYSICS ANALYSIS

COUPLING BETWEEN THE NEUTRONICS (APOLLO3®) THE

THERMAL-HYDRAULICS (FLICA4) AND THE FUEL

PERFORMANCE (ALCYONE/PLEIADES) FOR THE

MODELING OF A PWR ROD EJECTION ACCIDENT (REA)

| PAGE 1

Jean-Charles LE PALLEC1 ,K. Mer-Nkonga2, N. Crouzet1

1CEA France, DEN/DANS2CEA France, DEN/CAD

JUS 2016 – EDF LAB, Saclay, December 09

7 DÉCEMBRE 2016

| PAGE 2

OUTLINE

Context

CORPUS multi physics platform

REA Exercice

Conclusion and Prospects

CONTEXT

7 DÉCEMBRE 2016

| PAGE 3

CEA | 10 AVRIL 2012

� REA phenomenology

� REA challenges

REA PHENOMENOLOGY

7 DÉCEMBRE 2016 | PAGE 4JUS 2016 - EDF Lab, Saclay, December 09

1. Core power ↑↑↑↑ especially around the ejected control rod assembly2. Core power ↓↓↓↓ due to the Doppler (1st order) + moderator (2nd order) feedbacks 3. Core power ↓↓↓↓ due to the control rods emergency shutdown (‘scram’)

coreΓ

maxcoreP

maxt Fhot spot < 100 ms 10 Pnom 200 ms 20

Control rods ejection (0.1s) ��fast reactivity core transient (1s)

SAFETY CRITERIA: fuel temperature, fuel enthalpy, clad temperature

⇒⇒⇒⇒ Integrity of the first containment barrier (cladding)

��

REA CHALLENGES

| PAGE 5

Access to safety criteria = local responses (fuel)

MODELING FOR SAFETY ANALYSIS : methodological evolution

� 3D modeling

� multiphysics approach

ThermalhydraulicsModerator feedback

Fuel performanceDoppler feedback

NeutronicsCore power

Safety criteria

From conservatism to best-estimate (BE) approach2D static/1D kinetic 3D cinétique

BE modeling = CORPUS development frameworkJUS 2016 - EDF Lab, Saclay, December 09

CORPUS PRESENTATION

7 DÉCEMBRE 2016

| PAGE 6

CEA | 10 AVRIL 2012

� Motivation

� Perimeter

� Architecture

� Current modeling development

Coooorpus

7 DÉCEMBRE 2016 | PAGE 7

⇒⇒⇒⇒ Core design : LWR (900MWe,1300MWe, N4, EPR, GEN3+)⇒⇒⇒⇒ Accident scenarios : steady state and transient : RIA (MSLB, REA)

CORPUS: OVERVIEW (1/2)

A SALOME application for reactor multphysics analysis

JUS 2016 - EDF Lab, Saclay, December 09

CORPUS: OVERVIEW (2/2)


CRONOS2(Access)

FLICA4(Access)

CATHARE2(ICoCo)

Th. limit conditions

Core analysis(REA)

Integral plant analysis(MSLB)

Mixing grid application(MELANGE)

Interpolation process(INTERP2_5D)

APOLLO2Cross-sections

Library

CALCULATION SCHEMES

Coooorpus


CORPUS: ARCHITECTURE (1/2)


« Russian doll » structure based on SALOME environment

Coooorpus

CODESPrerequisisites (C, C++

Fortran libraries)

Codes C++ wrapper libraries(API). Generation of SALOME components with YACSGEN

Supervision of distributedcomponents (implementation

of multiphysics schemes).

…


CORPUS: ARCHITECTURE (2/2)


Coooorpus

Typical API used for CODE supervision

Method definition

initialize(), terminate() Initilize/finalize the problem

solve(), interate() Resolution of steady problems

computeTimeStep () Time step value estimation

initTimeStep (dt) Initialise all the variables for the time step

solveTimeStep () Start the calculation on the time step

validateTimeStep ()/abortTimeStep () Validate/Abort the time step calculation

save()/restore() Save the internal state, and restore it

setInputField(), getInputField() Field Exchange at MED format

ICOCO : standard API for code coupling shared by a large range of SALOME codes (neutronics, thermalhydraulics, fuel, from core to system description) adopted notably by the EU NURESIM platform


CORPUS : CURRENT MODELING DEVELOPMENT (1/4)

| PAGE 11

Existing modeling : internal fuel treatment in CRONOS2(C2) and FLICA4 (F4)Limitations = modeling limited to the thermal response calculation (heat conduction eq.)

� Dynamic fuel/clad gap: NO (� simplified Hgap model)� Fuel irradiation state (rim effect): NO

Target modeling : go beyond those limitations

BE fuel description challenges

Fuel performance

neutronic

thermohydraulique

Doppler Feedback Moderator Feedback

Heat exchange

Power1 – fgamma fgamma

Coooorpus

use of a dedicated code = ALCYONE

CRONOS2 �� APOLLO3® switch+ JUS 2016 - EDF Lab, Saclay, December 09



Development strategy

Neutronics

Thermalhydraulics

Fuel performance

Coooorpus

Sta

rtin

gpo

int

Intermediate modeling: APOLLO3®/ALCYONE coupling

Final target: APOLLO3®/FLICA4/ALCYONE coupling

AL

AP3

F4

AL

AP3

F4

C2

STEP by STEP …



PWR1300MWe –GEMMES managment(193 UOx assemblies - 24 with Gd)

� Ejection of the Control rods situated in H2 ass.� Hot spot in the H1 ass.

modeling steps(APOLLO3®/ALCYONE coupling)

REA scenario target

Coooorpus

STEP2Control Rod specification

APOLLO3®

STEP3REA transient

APOLLO3®/ALCYONE coupling

APOLLO3®/ALCYONE coupling

STEP1Irradiation state calculation (depletion)

Internal simplified fuel/fluid description

0: Fresh fuel assembly1: Assemblies batch 12: Assemblies batch 23: Assemblies batch 3




Coooorpus

⇒⇒⇒⇒ APOLLO3®/FLICA4/ALCYONE coupling on a mini-core desig n

Principle : to make the developments on a small core (mini-core denomination)submitted to a REA scenario accident and update them progressively in the fullcore design� Simplification of the coupling scheme analysis and the simulation in terms ofcomputation time + data analysis

Design simplification for calculation schemes develop ment



REA EXERCICE

7 DÉCEMBRE 2016

| PAGE 15

CEA | 10 AVRIL 2012

� Mini core presentation

� REA scenario

� Modeling

� First results

MINI-CORE PRESENTATION (ACCADEMIC CASE)


Geometric data Assembly pitch 0.21504 m

Fuel pins per assembly 264 Fuel Cell dimension 1.26 10-2 m

Active height 4.2672 m Reflector height 2×0.21 m (bottom/top)

Clad external radius 4,75 10-3 m Clad internal radius 4,1785 10-3 m Fuel pellet radius 4,096 10-3 m

isotopic data (fresh fuel) U235 enrichment 4%

MiniCore design

3D 3*3 fuel core with a reflector envelope Standard fuel assembly design

Control Rod to be ejected JUS 2016 - EDF Lab, Saclay, December 09

Coooorpus

RIA SCENARIO


STEP1

Core Power (Pcore) NOC * 110.0 10+06 W/ HS ** 10000 W

Average linear fuel power (Plin)

NOC 10849.46 W.m-1 HS 1W.m-1

Initial core Burn-up 0 MWd/t (fresh core) Depletion duration STEP1 result HS to NOC transition 1 day

STEP3 Initial Pcore/Plin HS level Initial core Burn-up STEP1 result Rod ejection duration 0.1s Transient duration 0.3 s

STEP1/STEP3 (common data) Fast neutron Flux *** 3.8 1012 n.J-1. m-1 × Plin Fuel cell mass flow 0.3307 kg.s-1 Outlet Pressure 1.55 107 Pa Inlet fluid temp. 563 K (*) NOC: Nominal Operating Condition (**) HS: Hot Shutdown (***) Eneutron>1Mev

Fuel/cladaccomodation

�� STEP 1: cycle length calculation � BU(x,y,z) at the beginning of the transient (EoC config.)�� STEP 2: characterization of the Control Rod to be ejected (CR worth)�� STEP 3: REA transient calculation

3 calculation steps


Coooorpus

APOLLO3-ALCYONE MODELINGCALCULATION SCHEME (1/3)


Models and data exchanges

INT

ER

PO

LAT

ION


Coooorpus

(+ simplified thermal hydraulics)

ρρρρfluid /Tfuel

Pfuel

Multi-threaded calculation

CODE SAMPLE

import Queue, threading

class ThreadOneAlcyoneStep(threading.Thread):

def __init__(self, queue_in, queue_out):

threading.Thread.__init__(self)

self.queue = queue_in # resources

self.queue_out = queue_out # results

def run(self):

while True:

ressources = self.queue.get()

pinId=ressource[0]

alcyone_compo=ressource[1]

# ETC

alcyone_compo.initTimeStep(currentTimeStep)

alcyone_compo.setInputField(“linpower", power)

if alcyone_compo.iterateTimeStep() : # send results in output queue

fuel_temperature=alcyone_compo.getOutputField("TEMPERATURE")

fcoolant_density=alcyone_compo.getOutputField("RHOK")

output=[pinId, fuel_temperature, coolant_density]

self.queue_out.put(output)

else:

# Stop computation

self.queue.task_done() # signals to queue that the job is done

7 DÉCEMBRE 2016 | PAGE 19CEA | 26 SEPTEMBRE 2012

Get results and Put them in out queue

Compute oneTime-step

Get theresources

Initialization


Code sample

Coooorpus


| PAGE 20

time marching management

�� Depletion (STEP1) �� REA transient (STEP3)

- Synchronous explicit scheme

- Time step (∆ti,i+1) determined by APOLLO3® � constant value during the transient (∆ti = 1.e-3s)

- Synchronous implicit Block Gauss-Seidel (BGS) coupling scheme with a relaxation method to improve efficiency

- Time step (∆ti,i+1) determined by ALCYONE (stability of the thermo-mechanical/thermal-hydraulics resolution) � If the current time step does not converged (due to a code or to the BGS coupling scheme), the time step is divided by two and the BGS computation is restarted

7 DÉCEMBRE 2016

AP3

ALC

ti ti+1Kinetic calculation

Kinetic calculation3

2

4

1

7 DÉCEMBRE 2016

AP3

ALC

ti ti+1

51

Depletion calculation

Depletion calculation3

BGS(CV criteria)

= Stationary calculation1

2

4JUS 2016 - EDF Lab, Saclay, December 09

Coooorpus


Depletion calculation (STEP 1)

CBoron BoD*

[ppm] BUEoD**

[MWd/t] APOLLO3® 1521 11046 APOLLO®/ ALCYONE

1499 (-22) 11025 (-21)

(*) Boron concentration at the Begin of Depletion (**) Core Burn-up at the End of Depletion

Limitation : each code runs its own depletion model that potentially lead to a drift in terms of BUcomparison of the burn-up evolution obtained by APOLLO3® and ALCYONE: close behavior of the 2 models � coherence between the two codes in terms of depletion

� effect of a fine fuel description on a depletion calculation without invalidating the simplified fuel/fluid modeling currently used for cycle length calculations

Coupling effects

Global effects

Local effects

APOLLO3-ALCYONE MODELINGFIRST RESULTS (1/2)


Coooorpus

Fraction of delayed neutron [pcm] 568 Control rod worth [pcm | $] 879 | 1.55 Adiabatic model ALCYONE Max. linear fuel Power (Pmax) [W.m-1] 775.103 954.103 linear fuel energy at t = 0.3s [J] 19075 23138 Pulse width at Pmax/2 [ms] 21 20 Max. Fxyz 4.17 4.15


REA transient (STEP 3)

consistence between the 2 models that gives a good level of confidence of the coupling APOLLO3®/ALCYONE

ρρρρ = 1,55$

APOLLO3-ALCYONE MODELINGFIRST RESULTS (2/2)


Coooorpus

| PAGE 23

APOLLO3® - FLICA4- ALCYONE MODELING


Coooorpus

Fuel:

Fluid:

REA transient (STEP 3)

“proof of concept” � coupling effect to be analysed

CONCLUSION AND PROSPECTS

7 DÉCEMBRE 2016

| PAGE 24

CEA | 10 AVRIL 2012

CONCLUSION AND PROSPECTS (1/2)


promising opening: first demonstration of the CORPU S capability to integrate a BE fuel description (ALCYONE) in a PWR core model f or depletion and transient

analysis

Prospects�� in terms of calculation schemes� Numerical aspect : calculation time optimisation and robustness improvement� Data exchanges : extension to the fast neutron flux from APOLLO3® to ALCYONE� Feedback models : Fuel effective temperature formula from TRowland to TAlcyone

Conclusion

�� in terms of scenario calculationaccademic case � realistic REA bias analysis (typically simplified fuel description versus BE modeling)


Coooorpus

7 DÉCEMBRE 2016

Thank you for your attention

Coooorpus


Standardized environment …Exchanged codes format (MED)Code running interface (ICoCo)

… adapted to CORPUS applications …Supervision of complex modeling � multi physics couplingYACS graphical interface � « User friendly » calculation management (interactivity tools like stop and go)

Why to use the SALOME plateform ?

… and CORPUS capabilities extension– Modeling coupling extension – Uncertainties analysis management

CORPUS: ARCHITECTURE (3/3) Coooorpus



Simulation tools to understand and predict fuel behavior under irradiation

Dev. framework: the PLEIADES software env.

C++ software architecture based on the SALOME norm for exchanges with other platforms (thermo-hydraulic and neutronic)

Modeling perimeter� Multidimensional approach (1D, 2D, 3D)

� Multiphysics modelling

Thermal/mechanical behaviourMaterial modifications under irradiationFission products inventorySimplified model for the fluid (coolant) flowSimplified model for the neutronic behavior

Focus on 1D scheme� 1 fuel pin/1 sub-chanel flow description

Several axial slices (usually 30 slices)1D radial calculation on every fuelslice 1D scheme for fuel rod modeling

T, P coolant

cladpellet

Slice n

Slice n+1 rpellet clad

Mechanical and thermal interactions

r

CoooorpusCURRENT MODELING DEVELOPMENT

ALCYONE for fuel performance


OverviewNew generation code, shared project with industry (EDF and AREVA)

3D deterministic multi-purpose code for any kind of reactor concepts

Neutronics at fuel pin to core scales

High Performance Computing (different levels of parallelization)

Focus on the Neutronic core calculationApproximate models of Boltzmann equation :

� Multigroup diffusion or SPN solver MINOS

Finite Elements for 3D extruded hexahedral and hexagonal structured meshes

� Multigroup SN or SPN solver MINARET

Finite Elements for 3D extruded unstructured meshes

Bateman equations for isotopic evolution (depletion)

| PAGE 29

CURRENT MODELING DEVELOPMENT

APOLLO3 * for neutronic modeling

Coooorpus

PWR

(*) D. Schneider et al., “APOLLO3®: CEA/DEN Deterministic Multi Purpose Code for Reactor Physics Analysis”, PHYSOR2016


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