modelling of the contamination transfer in nuclear ... · modelling of the contamination transfer...

Modelling of the contamination

transfer in nuclear reactors:

The OSCAR code

Applications to SFR and ITER

F. Dacquait, J.B. Génin, L. Brissonneau

CEA/DEN/Cadarache

1st IAEA Workshop on Challenges for Coolants in Fast Neutron

Spectrum Systems

Vienna (Austria), 5-7 July 2017 | PAGE 1 www.cea.fr

1st IAEA Workshop on Challenges for Coolants in Fast Neutron Spectrum Systems | Vienna (Austria) | 5-7 July 2017 | PAGE 2

Outline

Introduction

OSCAR: the main specifications

OSCAR-Fusion: Application to ITER

OSCAR-Na: Application to SFR

Conclusion

JUIN 2015

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Introduction

OSCAR: The main specifications



Conclusion


Introduction - Principle and stakes

Industrial issues:

• Radioprotection: Reduction of Occupational Radiation Exposure (ORE)

• Environment: Minimization of release/waste – Optimization of dismantling process –

Source term in case of accident/incident

• Availability: Optimization of reactor operation

Under neutron flux

Activation and release of ACPs

Out-of-flux

Corrosion and release of CPs

ACP transfer

Contamination

CP transfer

Activated Corrosion Products (ACPs)

85%

Fission products

5%

Activated structures

5%

Neutrons 5%

Collective dose for operation and

maintenance of PWRs

Principle of contamination transfer

in a nuclear cooling system

For ITER and SFR:

mainly due to ACPs as well


Introduction - Scientific process at CEA

OSCAR code Development – Validation – Simulation

PWR / NMP / JHR / ITER / SFR

Studies – Predictions

Valuations and solutions

•Study of

phenomenology

•Data acquisition

•Modelling

•Validation

Experiments in

test loops

• Corrosion/Release

(CORELE, autoclaves…)

• Solubility/Dissolution

kinetics (SOZIE…)

• Transfer/Deposition

(CIRENE)

Measurements in

nuclear reactors

• EMECC campaigns

(g surface activities)

• Filtrations / Samplings

EMECC measurement

Hot leg of a PWR

Radiotracers injection

pots of CIRENE

JUIN 2015

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Introduction




Conclusion



Objective

Simulation of contamination transfer in nuclear reactor systems during power

operation and during cold shutdown (PWR: 20350 °C - reducing/oxidizing - acid/alkaline)

Calculation of masses/activities of CPs/ACPs/FPs/Actinides in solid/liquid/gaseous phases of

nuclear circuits as a function of time (normal operation over several decades and transients

over several minutes/hours)

Development of a calculation code since 70’s: OSCAR (merge of former PACTOLE and

PROFIP codes in 2008)

Outil de Simulation de la ContAmination en Réacteur

(tOol of Simulation of ContAmination in Reactor)

OSCAR originally developed for PWR in collaboration with EDF and AREVA NP

Modular code (easy evolving tool)

Validation based on a large OPEX unique in the world (~400 EMECC campaigns)

Last version: OSCAR V1.3 released in 2014

Application to ITER: PACTOLE-ITER (1995)

PACTITER (1998) OSCAR-Fusion (2016)

Application to SFR: OSCAR-Na (2012)

SFR



Modelling - Discretization

Circuits discretized in

control volumes

according to:

• material

• geometry

• thermal-hydraulics

• neutronics

• operation

Up to 6 media in

each control volume

Particles Ions

Deposit/Outer oxide

Metal

Filters

Inner oxide

HL/COL/CL : Hot/CrossOver/Cold Leg

SG: Steam Generator

CVCS: Chemical and Volume Control System

PWR

Core



Modelling - Isotopes and mass balance equations

CPs/ACPs (OSCAR V1.3):

8 elements: Ni, Co, Fe, Mn, Cr, Zr, Ag, Zn

15 radioisotopes (short/long half-lifes)

Unsteady mass balance equation for each

isotope in each medium of each region:

• mi : mass of isotope i in a medium

• Jm : mass flux between 2 media or

2 isotopes or 2 regions

Source Sink

mmi JJ

t

m



Modelling - Transfer mechanisms of CPs

Metal Corrosion

Formation

Ions

Convection Purification

Filters

Activation Decay

Particles

Region k

Precipitation Dissolution

Erosion Deposition

Deposit/Outer oxide

Convection

Release

Injection

Inner oxide Formation

Dissolution Precipitation

Abrasion



Modelling - Corrosion-Release

Corrosion and release rates [𝑘𝑔 ∙ 𝑠−1]:

Empirical laws (material, chemistry, temperature)

User data (power law, logarithmic law, constant value per stage)

M Z+

M Z+ *M Z+

Release

Outer oxide growth

*M Z+ : radioactive metal ion

M Z+ : metal ion

Inner oxide growth M Z+

Corrosion

Chromite

Ferrite + pure phase

CormCorrosion VSJ RelmRelease VSJ



Modelling - Dissolution/Precipitation

Dissolution rate [kg ∙ 𝑠−1]

• Sw : wetted surface [m²]

• h : mass transfer coefficient of ions in fluid [m.s-1]

• Vdissol : dissolution surface reaction rate coefficient [m.s-1]

• : equilibrium concentration of element elt [kg.m-3]

• Celt : bulk concentration of element elt [kg.m-3]

Equilibrium concentrations and composition of ideal solid solution (mixed oxide and pure solid

phases in excess):

• calculated by PHREEQCEA (OSCAR chemistry module) (version of PHREEQC code

extended to 350 °C) and its thermodynamic database developed by CEA

• Depend on chemical conditions (pH, redox), bulk/wall temperature and masses of each

medium in each region

)(11

eltelt

eq

dissol

welt

ndissolutio CC

Vh

SJ

elt

eqC



Modelling - Erosion/Deposition

Erosion rate [𝑘𝑔 ∙ 𝑠−1]

• E : erosion coefficient [s-1] (based on Cleaver & Yates model)

• Y : erosion resistance [-]

• : mass of the deposit that can be eroded [kg]

Deposition rate [𝑘𝑔 ∙ 𝑠−1]

• Vdeposition : deposition velocity [m.s-1] taken into account Brownian diffusion, inertial

deposition (Beal model), sedimentation, thermophoresis and boiling deposition

• Cpart : particle concentration [kg.m-3]

erodErosion mE

J Y

erodm

part

depositionwDeposition CVSJ

rég

Fluide

p

K

E

75

2701log

JUIN 2015

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Introduction




Conclusion



ITER (fusion reactor) Tokamak Water

Cooling System consists of 3 Primary Heat

Transfer Systems (IBED, NBI, VV)

Compared to LWRs:

Similarities:

Coolant: water

≈Water characteristics

(thermohydraulic and chemical)

Materials: SS 316/304

Differences, mainly:

CuCrZr alloy (Plasma Facing

Components)

Pulsed mode operation

Neutron flux

OSCAR can be used for ITER &

DEMO with some minor adaptations

Typical ITER TCWS cooling loop (Gopalapillai et al., 2012)

Cooling water chemistry specification for plasma operation

(Gopalapillai et al., 2012)


OSCAR-Fusion:

OSCAR

Cu (thermodynamic data in PHREEQCEA and CuZrCr corrosion rate)

Activation reaction rates (fast neutron flux)

E.g. Simulation of the ITER DIV/LIM cooling loop using OSCAR-Fusion V1.3

DIV

HE

CVCS

Circuit discretization (Di Pace, 2003):

71 control volumes




Operating scenario (Di Pace, 2003)

0

50

100

150

200

250

0 500 1000 1500 2000 2500 3000 3500

Time (days)

Tem

pera

ture

(°C

)

Cold stby Cold stby

Baking Baking

Burn Burn Burn

Hot stby

Dwell +

Hot stby Hot stby

Dwell +

Hot stby

Out-of-flux wall g activities due to:

Generally 64Cu during plasma burn phases

60Co during the other phases

Total out-of-flux wall activity (Broutin, 2017)

E.g. Simulation using OSCAR-Fusion V1.3 (continued)



Issues/R&D needs (discussion with L. Di

Pace from ENEA):

Simulation of pulsed mode (in progress):

• succession of burn, hot and cold

stand-by, baking and shutdown

phases

• About 400,000 burn phases of 400 s

over about 20 years



Issues/R&D needs (continued):

Validation of OSCAR-Fusion against

experiments in ITER/DEMO PHTS

conditions

Optimization of chemistry conditioning for

each PHTS and each operating phase

Corrosion rates of steels and Cu alloys

(impact of Cu swirls?) in different

conditions

Cooling water chemistry specification for plasma operation

(Gopalapillai et al., 2012)

Impact of manufacturing process (surface finish)

Corrosion at material junctions like CuCrZr and SS: impact on contamination?

Effect of the magnetic field on the CP behaviour

…

JUIN 2015

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Introduction




Conclusion



2) ACPs transported by Na

3) Out-of-flux contamination

Precipitation on cold surfaces

1) Release from activated cladding Corrosion of cladding steel

1

3 3

SFR Sodium Fast Reactor

Coolant: Sodium - Temperature up to 600 °C

Adaptation of OSCAR to SFR

OSCAR-Na:

Architecture of OSCAR

specific corrosion-dissolution/precipitation model

Control volume k

ION

METAL

Interface

flux

Convection

Convection

Sodium


Corrosion-dissolution/precipitation model: (Polley & Skyrme, 1978) model

Interface flux:

: Chemical partition coefficient

Calculation:

Numerical method for solving the equation diffusion

Complete mass balance in the primary circuit

Iterations – convergence for each time step

'11

1

0

CC

kk

Cux

CD i

a

i

x


M.V. Polley and G. Skyrme, “An analysis

of radioactive corrosion product transfer

in sodium loop systems”, Journal of

Nuclear Materials 75 (1978) 226-237

eq

i

d

a

C

C

k

k

'

k

Steel Sodium D



E.g. Simulation of the PHENIX reactor using OSCAR-Na V1.3

• 15 core regions

• 10 IHX regions

• [O] = 1 ppm

• Purification : 0,14% primary flow

Fu

el

reg

ion

s

Simulation covers 1750 days

at nominal power

Calculation time ~ 30 minutes



E.g. Simulation of the PHENIX reactor using OSCAR-Na V1.3 (continued)

The global amount of contamination and the contamination profiles on

PHENIX IHX are correctly simulated using OSCAR-Na



Issues/R&D needs:

Data on oxide equilibrium concentrations (only pure element solubility in

sodium are known)

Data on diffusion coefficient in steel

Particle behaviour

Further OSCAR-Na validation work against OPEX on SFRs and experimental

loops

Modelling of contamination by fission products

JUIN 2015

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Introduction




Conclusion


Modelling of Contamination Transfer

(ITER and SFR)

Application

• Fusion reactor cooling water system

• SFR primary system

Main Radiation Effects

1. Formation of ACPs under neutron flux

2. Contamination of out-of-flux regions by ACPs

Research Details

• OSCAR-Fusion: Cu alloy added

• OSCAR-Na: Specific dissolution-precipitation model implemented

Major Issues and Challenges

Validation against experimental data (loop/reactor OPEX)

Achievement

• Adaptation of OSCAR (modular code) to different types of coolant

R&D Needs

• Fusion: Simulation of pulsed mode / Corrosion of Cu alloys (Cu swirls), steels / Optimization of water chemistry / Validation experiments / …

• SFR: Oxide solubility / Diffusion coefficient in steel / Particle behaviour / Validation / …

Conclusion - Graphview

F. Dacquait “Modelling of the contamination transfer in nuclear reactors: The OSCAR code - Applications to SFR and ITER”

Direction de l’Energie Nucléaire Département de Technologie Nucléaire Service de Mesures et modélisation des Transferts et des Accidents graves Laboratoire de Modélisation des interactions et Transferts en Réacteur

Commissariat à l’énergie atomique et aux énergies alternatives

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T. +33 (0)1 04 42 25 75 74 | F. +33 (0)1 42 25 47 77

Etablissement public à caractère industriel et commercial | RCS Paris B 775 685 019 JUIN 2015

| PAGE 28

Thank you for

your attention

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