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KIT – Universität des Landes Baden-Württemberg undnationales Forschungszentrum in der Helmholtz-Gemeinschaft www.kit.edu

Pb Alloys Coolant Chemistry and Structural Materials Performance: a Review

Concetta Fazio

Actinide and Fission Product Partitioning and Transmutation11th Information Exchange Meeting

San Francisco, USA1- 4 November 2010

Program Nuclear Saftey Research

Concetta Fazio Program Nuclear Safety Research2 1-4 November 2010

Outline

Pb alloys cooled nuclear system

Coolant chemistry control and Handling: some key issues

Solubility and Diffusivity dataOxygen measurement and adjustmentSolid Impurities Filtering Systems

Key Materials issues and latest results

Summary and outlook


Pb alloys cooled systems

15 Proton Proton beambeam1515 Proton Proton beambeam

ADS: The EFIT system

LFR: The ELSY system

Spallation Target: MEGAPIE


Operational conditions and materials selectionXT-ADS (LBE) LFR (Pb)

Core components: mechanical stresses: e.g. Hoop stress on cladding

9Cr F/M Steel

T 300 – 500 °C 400 – 530 °C

dpa Up to 160 Up to 100

flow ~ 2m/s ~ 2m/s

Reactor Vessel

Austenitic Steel

T 300 – 400 °C 400 – 430 °C

dpa < 0.02 < 0.003

flow ~ 1 m/s ~ 0.1 m/s

stress 50-150 MPa 80-150 MPa

Heat exchanger

Austenitic or F/M Steel

T 300 – 400 °C 400 – 480 °C

dpa < 0.02 < 0.03

flow ~ 1 m/s ~ 1 m/s

stress ~100 MPa 125-190 MPa

Spallation target

9Cr F/M Steel

T 240 - 340 °C -

dpa/yr Up to 40 -

flow ~ 3 m/s -

stress ~100 MPa + 40 fatigue cycles/yr -

LFR Pump: T= 480 °C; dpa < 0.03; flow = 10 m/s (on impeller)


Coolant chemistry and corrosion: a key item

500 600 700 800 900 1000

-500

-450

-400

-350

-300

-250

-200

10-4

10-6

Temperature (°K)

RT

ln p

O2 (

kJ/m

ol)

Bi2O3

PbO

NiO

Fe3O4

/FeO

200 300 400 500 600 700 800

10-28 10-26

PbO in Pb45Bi55

10-10

10-8

10-24

10-22

10-20

10-18

10-16

10-14

pO2

Temperature (°C)

O [wt%] in Pb O [wt%] in Pb45Bi55 from Orlov O [wt%] in Pb45Bi55 our calc.

(bar)

H2OH2

103

102

101

1

10-1

10-2

10-3

10-4

10-5

Oxidation of the steel surface The oxide layer can act as a protection barrier

HLM oxides precipitates (plugging!)

Ellingham Diagram

20 μm

PbBi

ferritelayer

20 μm

PbBi

Oxygen content in LBE < 10-9 wt.% T=400 °C

T91 Trans/interganular dissolutionAISI 316L Leaching of Ni and ferritisation

10000 h

[O2]LBE > 10-8 wt.% and < ΔG(PbO)400 °C < T < 550 °C

AISI 316L

Fe3O4

Fe,Cr spinel

Diffusione zone

T91


Coolant Chemistry and Handling: key issues

Fundamental data: Solubility and diffusivity of metallic and non metallic elements are needed.

Oxygen measurement: Oxygen sensor’s long-term reliability also in irradiation filed, and calibration

Oxygen control systems: gaseous H2/H2O or solid PbO mass exchange systems

Filtering systems: essential to remove solid impurities from the liquid and gas phase


Solubility and diffusivity data

Gas inletAr 99.999% (PO2 = 2·10-6)

LBE

Platinum gauze

YSZ

Gas outlet

Platinum WireMo wire

Coulometric Oxygen Pump

miror

Laser beam path

laser

lens

Laser-Induced Breakdown Spectroscopy

Development/adaptation of ad-hoc measurement techniques

Measurement of oxygen solubilityMeasurement of solubility of

metallic elements: e.g. NiCourtesy IQS Courtesy CEA


Solubility and diffusivity data: results

-0.7-0.6-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.50.60.7

1.1E-03 1.2E-03 1.3E-03 1.4E-03 1.5E-03 1.6E-03 1.7E-03

Martynov, Ivanov, Proceeding of four technical meeting 1998

Rosenblatt, Wilson, Proceeding of Fall Meeting of the Metallurgical Society of AIME, 1969

1/T (K)

Log

S Ni(w

t %)

L. Martinelli et al, LIBS and ICP AES results, 2009

Ni solubility

Courtesy IQS Courtesy CEA


Oxygen sensor: R&D on basic componentsSolid electrolyte (YSZ)• Optimization for mechanical strength

(e.g., Al2O3 addition)

Reference electrode assessment• Bi/Bi2O3 increases the risk of electrolyte

cracking• Use of Pt/air reduces the requirements on

mechanical stability of the electrolyte

Second (working) electrode assessment• Application of a protecting sheath around

the electrolyte gives rise to sensor fouling and should be avoided

Signal transmission• Issue to be addresses for application in

pool type reactors C. Schroer, KIT


Absolute accuracy• Can be ±5 mV (±10% cO)• Correction of thermoelectric

voltages is necessary for achieving this accuracy

In-plant testing• Method to distinguish between

functional and flawed sensors available

Long-term performance• in experimental facilities is

promising with respect to industrial application of electrochemical sensors in Pb alloys

Oxygen sensor performance

Sensor accuracy by setting different oxygen potentials in LBE

Long-term performances of sensors

C. Schroer, KIT


Avoid PbO formationFormation of protective oxide layers

Need for oxygen control


Oxygen control technologies: Solid Phase mass exchange

IPPE MX, Martynov, ICONE 17

F. Beauchamp, CEA

AdvantagesNo gas managementNo risks of plugging (oxide formation)Quite easy control by flow rate and temperature

DrawbacksMore complex design for MXpMore maintenance: pellets filling• Personal exposure

Risks of oxide precipitation on pellets• Sluggish kinetic for

dissolutionL. Brissonneau, CEA


Oxygen control technologies: Gas Phase mass exchange

G. Müller, A. Weisenburger KIT

AdvantagesSame device for O2 control and purification by H2.No intervention on the device in normal operationQuite easy to control automatically

DrawbacksRely on sensors if non equilibrium gases are usedNeed for exchange coefficient if equilibrium gases are usedLarge surface exchangeRisks of oxide formationLarge flow ratesRisk of contamination exposure for operators


Impurities removal technologies

L. Brissonneau, CEA

Poral

Dynalloy

Pall cartridge

Pressure drop vs. time

Filters have been tested:Maintenance problem have been encounteredFor assessment longer experiments are needed


Key materials issues for HLM systems

Compatibility with Pb and LBECorrosion / oxidation resistanceEnvironmental assisted degradation of

mechanical properties

Irradiation in a fast neutron and for ADS in a proton/neutron field

High dpa (cladding)High H and He (spallation target)coolant / irradiation synergetic effects


Corrosion / oxidation resistance

Bulk Material

LBE

Bulk Material

LBE

AISI 316L at 450 °C and low oxygen Courtesy CIEMAT

T91 at 450 °C and low oxygen Courtesy CIEMAT

AISI 316L at 550 °C and 10-6 wt.% oxygen (left low exposure time; right high exposure time) Courtesy KIT

T91 at 550 °C and 10-6 wt.% oxygen (left low exposure time; right high exposure time) Courtesy KIT


Mechanical behaviour in HLM

Creep-ruture test T91. Impact on LCF, fracture toughness and tensilehave been observed as well

LCF test AISI316L. Tensile and fracture toughness test have shown as well no effect


Summary T91 and AISI316LT T91 AISI 316L

Low (< ~ 400 °C)

• Irradiation H & E• Corrosion low • Impact on mechanical properties

if wetting and stress above certain values

• Irradiation H• Corrosion low • No Impact on mechanical

properties

Medium (≤ ~ 450 °C)

• Slight Irradiation H & E• Oxygen control stringent• Impact on mechanical properties

(see low T)

• No Irradiation H & E• Oxygen control stringent• No Impact on mechanical

properties

High (> 450 °C)

• No irradiation H & E• Oxygen control very stringent

(oxide layer thickness)• Impact on mechanical prop if

oxide layer fails

• No irradiation H & E (high dose swelling)

• Dissolution attack T> 500°C

• No impact on mechanical properties

In the high temperature range for both material corrosion protection would be mandatory


GESA for corrosion protection

Magnetic-coil Anode

GESA facilitycathode

Volumetric Heating

Melt layer

Surface alloyed layer

e--beam

LPPS sprayed FeCrAl layer

subs

trate

Tests on GESA

Results

Corrosion resistance

Erosion resistance

LCF No reductionCreep-to-rupture

No reduction

LISOR No corrosionHardening

600°C

1 m/s 1,8 m/s

3 m/s


Summary and outlook

HLM Chemistry and quality controlBasic phenomena have been understoodTechnologies have been tested on laboratory scale and in loop systemsSelection of best performing technology for large scale and pool type is neededTesting of these technologies in large scale pool type is needed

Materials in HLMBasic corrosion mechanism have been understoodBasic mechanical properties degradation mechanism have been understoodPositive impact of corrosion-protection barrier (e.g. GESA) has been assessed.Materials operational window have been identifiedStrategies on materials performance assessment for component lifetime estimation have to be defined


Acknowledgments: DEMETRA Partners

KIT GermanyAAA France

Ansaldo ItalyCEA France

CIEMAT Spain CNRS FranceCRS4 ItalyENEA Italy

ENEN: IQS KTH

RUB-LEE UCL

SpainSweden

Germany Belgium

FZR GermanyNRG NetherlandNRI Czech RepublicPSI Switzerland

SCK-CEN Belgium

http://www.kit.edu/


Thank you for your attention


Back-up


Ni sheet

Oxygen sensor

zoom

Laser-Induced Breakdown Spectroscopy: principle


Example of practical application: importance of oxide thickness

(D. Struwe, W. Pfrang, IRS/FZK)

Increase of clad temperature

Shift of the maximum temperature

Axial profiles of clad inner temperature modified calculation with different additional oxide layers

Oxide layer thickness should be limited to < 20-30 μm in order to keep margin on the maximum allowable temperature for the T91 steel.

Control of oxidation process in a reactor system might not be applicable

GESA surface alloyed steel can be seen as a solution


0.0 0.2 0.4 0.6 0.8 1.0

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

steady state 0.1 sec trip 0.5 sec trip 2.0 sec trip 10. sec tripG

AP C

ON

DU

CTA

NC

E (W

/M**

2-K

)

core height

Mechanical properties of materials: Fast Closure of gap between fuel and clad due to beam trips could lead to enhanced stress on the clad. Thermal-shock could affect the oxide integrity

Example of practical application: Importance of mechanical features

δ

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