LEAD COOLED REACTORS Time (h) Material Issues ... - Nuclear 2012/prezentari_sesiuni_plenare... · LEAD COOLED REACTORS ... 2 Nuclear 2012 –May 16-18, Pitesti, Romania KIT LEAD REACTORS

KIT – Universität des Landes Baden-Württemberg und

nationales Forschungszentrum in der Helmholtz-Gemeinschaft www.kit.edu

100 200 300 400 500 600 70010

-14

10-12

10-10

10-8

10-6

10-4

10-2

Tmax

Tmelt

Liquid metal corrosion

CO(Fe

3O

4)

COS

oxyge

n c

once

ntr

atio

n in

Pb

Bi in

wt%

temperature of PbBi in °C

LBE-oxidation

experimental matrix

0 150 300 450 600 750 9000,00

0,02

0,04

0,06

0,08

0,10

0,12

0,14

0,16

0,18

Vo

lum

e l

os

s (

mm

³)

Time (h)

T91

1.4970

T91+FeCrAlY+GESA

100 h = 3.6x106cycles

450°C,10-6

[O]wt%, 50N, 75µm, 10Hz

LEAD COOLED REACTORS

– Material Issues

A. Weisenburger

IHM/ KIT/ Campus Nord 2 | Alfons Weisenburger| HELIMNET Aix En Provence October 4-7, 2011Nuclear 2012 – May 16-18, Pitesti, Romania2 KIT

LEAD REACTORS – Material Issues

A. Weisenburger

Outline

• Introduction and motivation

• Corrosion / oxidation behavior of reference materials as function of temperature, time

and oxygen content - flow rate and stress

• Corrosion protection barrier development (GESA surface alloying process)

• Some material properties in liquid lead alloys – LCF, creep to rupture, fretting wear

•Oxidation – Corrosion feedback with reactor operation – Oxygen control

•Summary


Nuclear systems cooled with Pb, PbBi

ADS (EFIT, XT-

ADS, MYRRHA)

Coolant +

Target: Pb, LBE

Spallation

neutron source

(e.g. MEGAPIE)

Coolant +

Target: Pb, LBE

Generation IV (LFR

(ELSY) – ALFRED

Bor 60)

Coolant: Pb

SVBR - PbBi

Why Pb? - large liquid range (327 – 1745°C) – good neutronics – heat transfer – low

chemical activity – natural convection (passive safety)


Material availability and cost

Fabricability, joining technology

In service inspection

Non destructive examination techniques

Safety approach and licensingCodes and design methods

R&D effort needed to establish or complement

mechanical design rules and standards

Decommissioning and waste management

Requirements for materials

Courtesy: A. Almazouzi EDF


Technical challenges& Leading physical phenomena

60-year lifetime

Fast neutron damage (fuel and core materials)Effect of irradiation on microstructure, phase instability, precipitationSwelling growth, hardening, embrittlementEffect on tensile properties (yield strength, UTS, elongation…)Irradiation creep and creep rupture propertiesHydrogen and helium embrittlement

Liquid metal/structural material compatibilities Corrosion/erosionLiquid metal embrittlementCoolant influence on mechanical propertiesOxide scales – heat transfer degradation

Courtesy: A. Almazouzi EDF


Selection of possibly suitable steels for Pb cooled systems

Steels that are considered for liquid Pb, Pb-Bi systems are those employed

in nuclear applications.

Advantage of this selection is that these steels are:

• well characterized

• designed for low irradiation damage

• composed of low activation elements

• easy available

• licensed for nuclear application (not T91 and ODS)

Material C% Mn% Si% Cr% Ni% Mo% V% Nb%

1.4970 0.08-0.12 1.6-2.0 0.25-0.45 14.5-15.5 15-16 1.05-1.25

-- --

316L 0,3 2 1 16.5-18.5 11-14 2-2.5 -- --

T91 0.08-0.12 0.3-0.6 0.2-0.5 8-9.5 0-0.02 0.85-1.05

0.25 0.01

Steel C Cr W Y Ti O N Ar S+P

ODS 0.13 8.85 1.94 0.27 0.20 0.17 0.011 0.005 0.004

For high Temperature (> 550°C) and high burn-up (≥ 20%) ODS steels have been indicated as

most promising materials in Fission for future reactors


Components Material Min./Max Temp.

Normal Operation

(°C)

Max. Lead

velocity

(m/s)

Max. Radiation

damage

(dpa/y)

Max. Radiation

damage

(dpa)

Reactor Vessel AISI316L 380÷430 0.1 < 10-5 0.0002

Inner Vessel AISI316L 380÷480 0.2 0.1 2.1

Steam Generator T91/AISI316L 380÷480 0.6 < 10-5 0.0001

Primary Pumps MAXTHAL (Ti3SiC2)?

Coated T91 or SS

(Aluminised, Ta) ?

380÷480 10 < 10-5 0.0001

FA Clad

FA Structures

T91/15-15Ti 380÷550

380÷530

1

2

-

-

(100)

(100)

Dummy Assemblies T91 380÷480 0.01 - (100)

Refueling Equipment AISI316L 380÷480 0.2 0.02 0.3

DHR Heat Exchanger T91 380÷430 0.2 < 10-5 0.0001

Material and Operating Conditions for ELSY /ALFRED, ELFR main

components (Pb)

Data given by Luigi Mansani


Liquid metal (Pb/PbBi) - steel compatibility

• Dissolution of alloying elements into liquid metal (W<<Fe, Cr<Ni)

• Oxidation in oxygen containing Pb alloy

• Erosion in dynamic systems - fretting corrosion

• Mass transport of structural materials in liquid metal systems due to thermal

gradients; dissolution in hot zones and deposition in colder regions plugging

• Liquid metal embrittlement (with and without irradiation)

Solubility of steel elements in Pb and PbBi

Way out:

Oxide scale on the steel surface

prevent the dissolution

liquid metal steelsteel

T1

aXT1

T2

aXT2

T1 > T2

aXT1 > aLM > aXT2

oxide scaleoxide scale

diffusion barrier for Cations!

350 400 450 500 550 600 650 700 750

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1

so

lub

ility

lo

gS

(w

t%)

Temperature (°C)

Pb PbBi

Ni

Cr

Fe

Al

Or – non soluble materials – also as coatings

W, Ta require oxygen free Pb/PbBi500 600 700 800 900 1000

-900

-850

-800

-750

-700

-650

-600

-550

-500

-450

-400

-350

-300

-250

-200

Ta 2O 5

10-4

10-6

Temperature (°K)

RT

ln

pO

2

(k

J/m

ol)

Bi2O 3

PbO NiO

Fe3O 4

/FeO

TiO2

Cr2O3

200 300 400 500 600 700 800

10-28

10-26

PbO in Pb 45Bi

55

10-10

10-8

10-24

10-22

10-20

10-18

10-16

10-14

pO

2

Temperature (°C)

O [wt%] in Pb

O [wt%] in Pb45

Bi55

from Orlov

O [wt%] in Pb45

Bi55

our calc.

(bar)

H2O

H2

103

102

101

1

10-1

10-2

10-3

10-4

10-5


Material compatibility of steels with Pb and PbBi

F/M steel / T91

oxide

200µm10000 h

• huge oxidation rate

of F/M-9Cr-steels

- frequent spallation of oxides

due to growth stress

- reduced heat removal

capability

Severe dissolution of

alloying elements (Ni)

dissolution rate up to 1 µm/h

austenitic steel / 1.4970

Two major effects due to corrosion:

Structural integrity – metal recession – dissolution, oxidation (Spinel + IOZ)

Heat transfer/conduction - : oxidation (magnetite + spinel) 10µm scale 10K increase

30µm



A. Weisenburger

Outline


• Corrosion / oxidation behavior of reference materials as function of temperature,

time and oxygen content - flow rate and stress



• Oxidation – Corrosion feedback with reactor operation – Oxygen control

•Summary


0,0010 0,0012 0,0014 0,0016 0,0018 0,0020 0,0022

-14

-12

-10

-8

-6

-4

-2

*

Te = 300 - 600ºC

t = 100 - 10000 h

[O] = 10-11

wt% - saturation

Fe-Cr-Ni steels in stagnant LBE

Oxidation

Dissolution

T (ºC)

182227283352441727 560

Lo

g C

(%

wt)

1/T (ºK)

PbO

Fe3

O4

0,0010 0,0012 0,0014 0,0016 0,0018 0,0020 0,0022

-14

-12

-10

-8

-6

-4

-2

Te = 300 - 600ºC

t = 300 - 15000 h

[O] = 10-9 - 10

-4 wt%

Fe3

O4

PbO

Fe-Cr-Ni steels in flowing LBE

Oxidation

Dissolution

T (ºC)

182227283352441727 560

Lo

g C

(%

wt)

1/T (ºK)

Not many experiments at 500°C and below

– especially at proper oxygen

Quite different results – oxidation and

dissolution observed at same conditions

Duration of experiments? – only very little

number of experiments are performed in

pure Pb

Most experiments have

less than 3000 h duration

long term prediction?

Oxidation rate?

Compatibilty of 316L with Pb/PbBi – HLM Handbook

LBE

Fe

Bulk Material

316 at 300°C

no effect after 10000h(Ciemat)

316L at 450°C10-6 stagnant PbBi

Oxidation – 5000h

10-8 flowing PbBi

dissolution after 2000h (Ciemat)

316 at 450°C

316 500°C 10-6 10000h

stagnant PbBi316 500°C 10-6 10000h

Flowing Pb (ENEA)

316L start of dissolution in

stagnant PbBi 10-6wt%

oxygenDue to lower

solubility in Pb

these starting of

dissolution might

or better will shift

Most exposures <

3000h


0 2000 4000 6000 8000 10000

0

1

2

3

4

5

6

7

8

9

10

Heinzel 10-6 COSTA

316 JNC 10-6 COSTA

CHEOPE (Pb) 10-6

recent experiments at 10-6

recent experiment at 10-8

oxid

e th

ickn

ess [µ

m]

time [h]

500°C / 316 und 1.4970

0.09

1.12

dissolution attack at 10-8

Oxide scale growth on 316 type steels data from KIT and ENEA (Pb)

Starting dissolution

attack in stagnant

PbB at 10-6 oxygen

tktx )(


9 Cr steel T91 compatibility with lead alloys

480°C 10-6 6578h„s

(IPPE/KIT)

450°C 10-8 10000h„s

(LINCE - CIEMAT)

550°C 10-6 4015

(CORRIDA- KIT)

In LBE at low oxygen (10-8 wt%) 300°C no signs of attack – no significant oxidation

450°C 10µm oxide scales

In LBE at “normal” oxygen (10-6wt%)480°C progressive oxide growth – 30µm – 6587h

550°C 1m/s progressive oxide growth – 40µm - 6587h

550°C 2m/s progressive oxide growth – no magnetite -~ 40µm – 10000h

In Pb at “normal” oxygen (10-6wt%) – similar to LBE500°C progressive oxide growth -32µm – 10000h

Only at high temperatures >550°C dissolution attack an issue

LBE

Pb500°C 10-6 10000h„s

(CHEOPE - ENEA)

Bulk Material

LBE

Oxide layer

600°C – 2000h

30µm50 µm


Comparison of long term corrosion experiments of T91

in PbBi 10-6 wt% oxygen performed in different loops

with different flow velocity

0 5000 10000 15000 20000

0

20

40

60

80

100

IPPE - spinel + magnetite

0.22*t0,5

Spinel (IPPE)

SpinelMagn

Spinel (COSTA)

SpinelMagn

Spinel (pressurized tube)

SpinelMagn

Spinel (velocity exp.)

SpinelMagn

scale

th

ickne

ss [µ

m]

Zeit [h]

0.5*t0,5

T91 / 550°C / 10-6wt% O

21.3(log(t+267)-51.6

IPPE - spinel

CORRIDA metal recesion

0 5000 10000 15000 20000 250000

20

40

60

80

100

480 °C

550 °C

450 °C

420 °C

oxid

e s

ca

le t

hic

kn

ess [

µm

]

time [h]

T91 at different temperatures

10-6 wt%

Pb 500°C

PbBi 10-8

450°C

300°C

At 550 °C data from CORRIDA 2m/s and IPPE 1m/s

In similiar range - if spread of data is considered

Higher CORRIDA spinel data similar to IPPE spinel +

magnetite

t35.0

t25.0

t17.0

t5.0550°C

480°C

450°C

420°C

Parabolic oxidation – safe approximation

x(t)=k t35.0

k(T): - 0.897+0.00254*(T[°C])



A. Weisenburger

Outline







•Summary


Corrosion protection barriers - Thin protective surface

layers

Al2O3

Al2O3 layer

Fe(Cr,Al)-phase

Steel

Requirements

Corrosion resistant in HLM up to ca. 650 °C

Self healing of mechanically damaged layers

No negative influence on mechanical properties

Irradiation stability under relevant fluxes

The coating/alloying process must be of industrial

relevance - LPPS of FeCrAl powder

Oxide map of FeCrAl - oxide

at 900 °C


Surface modification using Pulsed Electron Beams (GESA)

(Process development in cooperation with NIIEFA, St. Petersburg)

Volumetric Heating:

rate: < 109 K/s

time: < 40 µs

Melt layer:

depth: < 100 µm

cooling:< 107 K/s

(heat conduction)

Surface alloyed

layer

e--

beam

Magnetic

-

coil

Anode

Target

GESA facility

Electron beam Parameter:

Electron Energy:125 keV

Power density : ~ 2 MW/cm²

Pulse duration

controllable: < 40 µs

Beam diameter: ~ 4cm GESA I

Treatable length ~ 30 cm GESA IV

LPPS sprayed

FeCrAl layer

T91

Substrate temperature remains relatively low – no

micro-structural changes in T91 observed

cathode


Al content ~ 10 wt%

T91 + FeCrAlY layer before and after surface modification

0 10 20 30 40

0

10

20

30

40

50

60

70

80

90

100

Fe,

Cr,

Al co

nte

nt

in %

distance from surface in m

Fe

Cr

Al

GESA treatment leads to:

metallic bonding – pore removal – surface smoothening and reduced Al content

0 5 10 15 20 25

0

10

20

30

40

50

60

70

80

90

100

Fe,

Cr,

Al contn

et

in %

distance from surface

Fe

Cr

AlAl content ~ 7 - 8 wt%

As

sprayed


Pb/PbBi compatibility of “perfect” Al surface alloyed steel

at optimal oxygen concentration 10-6 wt%

10000 h10000 h 10000 h

500°C 550 °C 600°C

Up to 600°C and 10000 h no

corrosion attack and no visible

oxidation.

Thin alumina scales protect the

surface alloyed steel.

20µm 20µm20µm

5000 h at 600 °C in flowing LBE (10-6 wt%)

GESA treated FeCrAlY


Required Al content to from thin Al-rich oxide scalesFeCrAl(Y) –GESA modified layers (400°C – 550 °C)

Al> 8wt% formation of thin Al-.rich scales – more Cr is

beneficial – reduces oxygen diffusion into bulk

Future work will include third element effect (Ce, Zr, ….)

10 -6 wt% oxygen

Al content measured with EDX just below the surface – 100nm Al2O3 scale

would reduce the Al content below the scale by about 1% - accuracy of EDX

0 500 1000 1500 2000 2500 3000 3500 4000

0

20

40

60

An

teil

in A

t%

Sputterzeit in s

Al

Alox

O

Cr

Fe

Pb

500°C

XPS at 500°C surface

Dedicated presentation by Adrian Jianu


Maxthal Ti3SiC2 – exposure to Pb

4000h at 550 °C 2000h at 750 °C

Formation of thin protective TiO2 and mixed Ti, Si oxide scales

No Pb attack and penetration

Good corrosion resistance


Other materials - Ta - almost no solubility in Pb Oxidation potential compared to PbO and oxygen containing Pb

Cr2O3

Ta2O5

Al2O3

Fe3O4

PbO NiO10-4

10-6

10-8

Oxid

ati

on

po

ten

tial

Temperature °C

Not possible as cladding

– irradiation

If Ta is considered the

oxygen potential -

concentration has to be

kept at very low values

Kinetics of oxidation

might help exposure

experiments of Ta stripes

in Pb and PbBi were

performed

In oxygen containing Pb

(oxygen content

sufficiently high for steel

protection) Ta will

oxidize 300 500 700


020406080

100120140160

0

100

200

300

400

500

20 30 40 50 60 70 80 90

0

500

1000

1500

020406080

100120

550°C / 10-6wt% / 518h

400°C / sat / 812h

2 Theta / ° (Scan Axis: 2:1 sym.)

Ta original

Inte

nsity / c

ps 450°C / 10-6 / 1014h

Thin Ta foil after 550 °C 10-6 wt% 500h

Ta2O5


Hardness measurement (Hv 0,1)

Original: ~ 100 HV – 400°C sat.: ~340 HV

Diagramm: F. Benesovsky, Plansee Proc. 2nd Seminar,

Reuttle, Tyrol 1955 [1956] S. 254/67, 263 in Gmelins

Handbuch Der Anorganischen Chemie, 8. Auflage,

Tantal, Teil B-Lieferung 1, Verlag Chemie GmbH

Weinheim/Bergstr.

0 200 400 600 800 1000 1200 1400 1600 1800 2000

200

220

240

260

280

300

320

340

360

380

400

420

440

ha

rdn

ess [H

V 0

,1]

deep [µm]

500°C 384h

550°C 384h

550°C 956h

Ta 10-6wt% 500 and 550°C

Oxygen diffusion into the Ta

increased hardness

embrittlement

Massive (2mm) Ta blocks



A. Weisenburger

Outline





• Combined effects corrosion + erosion, corrosion/wear/Creep to rupture

Liquid Metal Embrittlement


• Summary


T91 cladding tubes with and without GESA modified FeCrAlY coating

Experiment with different velocities at 550 °C, 2000 h

100mm 50mm 100mm 50mm 50mm

100mm

V=1 м/s V=2 м/s V=3 м/s

LBE

1m/s vPbBi 1.7 m/s 3 m/s

1m/s: magnetite scale

1.7m/s: small remains,

3m/s: no magnetite scale.

Spinel and internal

oxidation zone similar for all

3 velocities.

no influence

of flow velocity on

surface appearance

thin alumina scales

T91

original

T91+Fe

CrAlY+

GESA


Attack visualized

at a cross section

No erosion here

Examples for Erosion of 316L steel by “fast flowing” liquid Pb

No systematic investigation

so far

Specific flow patterns

(turbulent) can result in

severe material loss (erosion)

Has to be avoided


0 150 300 450 600 750 9000,00

0,02

0,04

0,06

0,08

0,10

0,12

0,14

0,16

0,18

Vo

lum

e l

os

s (

mm

³)

Time (h)

T91

1.4970

T91+FeCrAlY+GESA

100 h = 3.6x106cycles

450°C,10-6

[O]wt%, 50N, 75µm, 10Hz

Fretting damage /time for 1.4970 in Pb – 450°C 10-6wt% oxygen

10 µm

COMPACTED

SCALEDISSOLUTION

ATTACK

- Oxide scale growth on not-fretted areas (Fe-Cr

spinel)

- Ni depletion in the fretted area

- Compacted scale: oxide and metal debris (Ni

depleted)

- Contact Pb-bare surface of the alloy dissolution

- Periodic load fatigue cracking

- Relation fretting damage- Ni dissolution

Fe-Cr spinel oxide

10 µm

50N – 75µm 10 Hz


Pre immersion corrosion fatigue resistance decreases

Pre immersion oxidation fatigue resistance : OK

Wetting – direct interaction of HLM with steel required

0,1

1

10

102

103

104

105

AIR_ as receivedLBE_ as receivedLBE_pre corrodedLBE_pre oxided

Tota

l st

rain

range

t (

%)

Number of cycles to failure

Test temperature : 300°C

t

--------

t----------

t

--------

t----------

LCF - liquid metal corrosion – mechanical damage interaction ?

J.B. Vogt – 300°C


Significant reduction of creep strength of T91

in contact with liquid LBE

LBE reduces the surface energy and

penetrates at the grain boundaries – cracks

along grain boundaries

10 100 1000 10000

100

150

200

250

300

T91 original in Air

T91 original in LBE

T91 + GESA in LBE Str

ess (

MP

a)

time to rupture (h)

Stress vs time to rupture of T91 original

and with GESA modifed FeCrAly surface

layer

GESA modified FeCrAlY coating reduces

eliminates the influence of LBE

No cracks no LBE influence

Influence of oxide scale on creep rupture strenght



A. Weisenburger

Outline





• Combined effects corrosion + erosion, corrosion/wear/Creep to rupture

Liquid Metal Embrittlement


• Summary


We need oxide scale formation as function of time and temperature

As example:

Oxide scale growth on EFIT fuel pin 15-15Ti , wrapper – T91 - ALFRED

Assuming parabolic growth

4000 5000 6000 7000 8000

400

420

440

460

480

Te

mp

era

ture

°C

lenght of fuel cladding

For fuel cladding: Temperature distribution along

cladding (x1……x4)

sp, = 1355.5m2, swo = 1095 m², swi =1040 m2, Ftot. = 3491m2

tktx )(

C])(T[0.002540.897- k(T)

T(x))dx(t, F(231.55

64 = T)(t,owt

x4

x1

Oxide scale growth – oxygen needed (oxygen control)

filtering (spallation)

tTTtd )410831.0(),( 15-15Ti (400 – 550°C)

T91 (400 – 550 °C)


Oxygen consumption in g/h of fuel assembly (EFIT data)

15-15Ti clad, T91 wrapper

total Pb volume around fuel elements [EFIT-data] = 53.71m3 = 609071.4kg.

If Pb contains 10-5wt% oxygen it contains 61g oxygen just sufficient

oxygen to prevent oxygen depletion by oxidation


Summary

• Solubility, oxygen potential, dissolution and oxidation kinetics are key parameters for material

compatibility

• Temperature limits for corrosion (dissolution) of steels in Pb/PbBi

316 type steels: Tlimit < 450°C might be 500°C in Pb – to be assured

T91 type F/M steels Tlimit< 550 °C

• Oxidation of F/M steels above 450°C insufficient heat transfer capability oxygen control

• Turbulent flow pattern severe erosion requires further investigation

• Surface protection of steels (LPPS FeCrAlY + GESA) allows to increase the temperature limit

above 550°C

Selective thin Al2O3 scales forming on top increase heat transfer capability and reduce

corrosion attack

• Reduced creep strength of T91 at 550 °C in PbBi / LME has to be considered for T91 type steels

• Amount of oxygen in Pb is rather small – severe oxidation might cause depletion

Oxidation (oxide scale formation and associated oxygen consumption) has to be considered

filtering capacity to be adapted to the amount of oxides formed (spallation)


Thank you

The organizer for invitation

The audience for kind attention

Wladimir An, Mattia Del Giacco, Renate Fetzer, Annette Heinzel, Adrian Jianu, Fabian Lang,

Georg Müller, Robin Beckers, Frank Zimmermann

Documents

LEAD COOLED REACTORS Time (h) Material Issues ... - Nuclear 2012/prezentari_sesiuni_plenare... · LEAD COOLED REACTORS ... 2 Nuclear 2012 –May 16-18, Pitesti, Romania KIT LEAD REACTORS