> areva np gmbh - atoms for peace and development · pdf fileareva np > areva np gmbh...

AREVA NP> AREVA NP G

mbH <

The passing on, as well as the copying, distribution and/or adaptation of this document, exploitation and communication of its contents without expressed authorization is prohibited. Contravention entails liability for the payment of damages. All rights reserved in the event of patent, utility model or ornamental design registration.

IAEA

NTCMM-G, A. Nopper, IAEA Regional Workshop South America, December 2008 Argentinia

AREVA NP > AREVA NP GmbH <

The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-induced material degradationBasics, Effects and Countermeasures

Helmut NopperAreva NP, NTCMM-G

The reproduction, transmission or use of this document or its contents is not permitted without express written authority. Offenders will be liable for damages. All rights, including rights created by patent grant or registration of a utility model or design, are reserved.

3AREVA NP > AREVA NP GmbH < All rights are reserved, see liability notice.

The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-induced material degradation- Content

� Introduction� Flow-induced material degradation mechanism� Flow-accelerated corrosion

(Introduction, Corrosion process, Influence parameter)� Cavitation erosion

(Introduction, Mechanism, Risk determination)� Droplet impingement erosion

(Introduction, Mechanism, Sensebility) � Prediction of risk � Countermeasures

(FAC program, Optimized water chemistry, Material concept, Repair technologies)

4AREVA NP

> AREVA NP Gm

bH <All rights are reserved, see liability notice.


IAEA


Flow-induced material degradation-Types, definitions, influencing parameters

Introduction


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-induced material degradation- Types, definitions, influencing parameters

Single-Phase Flow( Water )

Two-Phase Flow( Water / Steam )

Flow-AcceleratedCorrosionCavitation Erosion Droplet Impingement

ErosionDefinition:Deep localized degradation in pumps, but also down-stream of internals and valves, caused by cavitation, i.e. violent collapse of steam bubbles in water flownear solid parts, governed by physical fluid and material properties

Definition:Erosive destruction of oxide layers due to turbulent water or wet steam flow followed by corrosion and dissolution of the unprotected wall, leads to a coherent area of degradation, governed by thermal-hydraulic properties, water chemistry, composition of material

Definition:Deep localized degradation due to the impact of liquid drops carried by wet steam flow, governed byphysical fluid and material properties

FlowDropletimpingementArea of highmetal loss

Water streaksdue to secondary flowArea of high

metal loss

Water film

Droplets

Flow core

Metal loss caused byerosion corrosion(mass transfer)

Turbulent boundary layerSteel

Fe(OH)2

FeOH

Flow-Induced Material Degradation

6AREVA NP

> AREVA NP Gm



IAEA


Flow-induced material degradation -Basics, effects and countermeasures

Flow-acceleratedcorrosion(Erosion corrosion)


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-accelerated corrosion- Introduction (1)

� FAC is a chemical corrosion process assisted by fluid dynamic mechanisms� FAC results in wall thinning

from piping, vessels, and equipment made of carbon steel� FAC occurs only under

certain conditions of flow,temperature, chemistry, geometry and material Unfortunately, those conditions are

common in most of the high-energy piping in power plants.


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-accelerated corrosion- Introduction (2)

� FAC is one of the most frequently experienced causes of component failures for power plants

� Undetected, FAC will causeleaks and ruptures without preceding ‘leak before break’ indication.

� Consequently, FAC is a major issue for safety, reliability and costs

Due to FAC four men were killed in 1986, two workers in 1995 and a failure in 2004 caused five fatalities.


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-accelerated corrosion- Corrosion process (1)

> A protective oxide layer is formed by the chemical reaction of the water flow at the inner piping material

� Magnetite Fe3O4 – (tri iron tetra oxide)oxidized Fe with water below 560°C, forms the thermo-solidly oxide Fe3O4

3Fe + 4H2O ⇒ Fe3O4 + 4H2

� Hematite a, b, g - Fe2O3 – (di iron trioxide)- this occurs with O2 under pressure 2Fe + 1 ½ O2 ⇒ a - Fe2O3

- dehydration of Fe(OH)2 at high temperature2Fe(OH)2 + ½ O2 ⇒ b - Fe2O3 + 2H2O

- or oxidation of Fe3O4 to g - Fe2O3

Oxide layer protects against erosion corrosion

Fe3O4

Fe2O3

WaterFlow

OxideBaseMetal


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA



> On carbon or low-alloyed steel the oxide layer is porous and Fe2+ can diffuse into a stream of flowing water or water-steam mixture

> The oxide layer becomes thinner and less protective against wall thinning

> For Ni/Cr/Mo-Steels and stainless steels the layers are more protective as continuous oxide layers exist. This fact strongly limits the diffusion of ferrous ions through the pores of the oxide layer.

> The hydrogen produced at the metal-oxide interface can diffuse into water or through the metal. Oxide layer

protects against erosion corrosion

Fe3O4

WaterFlow

OxideBaseMetal

H2

H2

Fe2+


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA



> For a steady state process the Fe3O4 dissolution rate must be equal to the Fe3O4growth rate. > The dissolution rate depends on the pH-Value.> A further process is the mass transfer of the Fe2+- Ions into the water flow. The removal of ferrous ions strongly depends on how the water flow (velocity, local turbulence of flow) passes the oxide-water interface

> Damage caused by FAC can be characterized as a general reduction of wall thickness rather than a local attack

H2H2 Fe2+

Flow core

Metal loss caused byerosion corrosion(mass transfer)

Turbulent boundary layer

Fe(OH)2

FeOH

Velocity profile

WaterFlow

OxideBaseMetal

12AREVA NP

> AREVA NP Gm



IAEA


Flow-accelerated corrosion-Characterization

Tiger striping in two-phase flows

100 µm

Horseshoe pits in single phase flow

13AREVA NP

> AREVA NP Gm



IAEA


ChemistryOperation Material

Flow-induced material degradation

Flow-accelerated corrosion-Influencing parameters (1)


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-accelerated corrosion- Influencing parameters (2)

7 8 9 10 11pH 25°C

mm/aWall thinning rate> pH value (of the water flow)

� wall thinning is constant on a high level up to a value of 8.0

� in the range between 8.0 and 9.0 wall thinning is reduced markable

� above a value of 9.0 thinning rates decrease drastically

� above a value of 9.7 FAC wall thinning can be neglected

The pH has a significant impact on the solubility of magnetite. High pH values reduce the potential for chemical dissolution.


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


The chart represents the specific material loss rate for different materials and flow conditions versus the pH value. These are experimental results from our ‘Benson’ test facility in Erlangen. The curves for 13CrMo44 or 15Mo3 show that a strong diffusion of ferrous ions is not given due to a distinctive and more protective oxide layer.

Note: Under two-phase conditions, the important parameter is the pH of the liquid phase, which can be different from the bulk pH due to partitioning of the species involved.

*Source: Heitmann and Kastner: “Proceedings of the International Specilist’s Meeting on FAC of Steels in High Temperature Water and Wet Steam”



The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA



0 100 200 300 400

mm/aWall thinning rate

Oxygen concentrationppb

> Oxygen concentration � highest thinning rates are observed below 10 ppb (parts per billions; µg/kg)

� in the range between 10 and 40 ppb wall thinning is reduced drastically

� above a value of 90 ppb wall thinning can be neglected

The oxygen has a beneficial effect, as oxygen promotes the transformation of magnetite to hematite.


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


26 NiCrMoV 11 5

30 CrMoNiV 4 11

13 CrMo 4 4

GS-18 CrMo 9 10

10 CrMo 9 10

X20 Cr 13

G-X8 CrNiMo 12

X10 CrNiTi 18 9

15 NiCuMoNb 5

15 Mo 3

RSt 37.2

Material 0 maxWall thinning

mm/a

Auste

nitic

stainl

ess

steels

Ferri

tic st

eels

St 37.2 + 0.5 mmMetco 33 layerSt 37.2 + 0.5 mm

Ni layer Coate

dste

els

pH O 279.5 < 5 ppb7

500 ppb

< 5 ppb


> Material (alloy content) � highest wall thinning is observed with non-alloyed materials (carbon steel)

� increasing contents of chromium, copper and molybdenum decrease the thinning rates

� a chromium content of 2.5% reduces wall thinning drastically

� stainless steel is resistant against FAC


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA



0 10 20 30 40

mm/aWall thinning rate

Flow velocitym/s

> Velocity of flow� thinning rates are correlated to flow velocity� highest wall thinning is observed at high flow velocities

� but wall thinning occurs already with low flow velocities

The flow velocity influences the mass transfer between the metal surface and the fluid. The FAC rate increases proportionally with increasing flow velocity.


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA



max

0.00 50 100 150 °C 250

mm/a

Wall thinning

Water temperature

> Temperature� below 40°C and above 260°C thinning rates are low

� highest thinning rates are observed at some 150°C

The temperature affects the solubility the oxide layer. It alsoinfluences thermodynamic parameters, which have an impact on the mass transfer.


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


> Geometry� thinning rates are correlated to the local turbulence of the flow

� geometrical arrangement influences the local turbulence of the flow

� geometrical arrangements which induce high turbulence into the flow lead to higher thinning rates

0 0.2 0.4 0.6 0.8 1.0Geometry factor k c

0.0

mm/a

Wall thinning

Bends

Pipe

Orifice

Valves

The geometry effect on FAC is caused by the local intensity of turbulence, which enhances the mass transfer between the oxide film and the water.



The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA



1.0

0.8

0.6

0.4

0.2

0.0

Geometry factor

5 10 15 20 300 z / D25

Piping element Ageometry factor kc, A

Piping element Bgeometry factor kc, B

> Upstream flow effect (UFE)

(kc, B)total = kc, B + Dkc, A

(kc, B)total < 1.0


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA



> Flow type (water-steam flow)� water-steam flow influences directly water chemical parameters because of the different distribution behaviour of alkalizing agents and oxygen

� flow type also influences local turbulence of the flow

NH3,steam

NH3,water

operating temperature [ °C ]

distrib

ution

coeff

icient

[ -]

0

5

10

15

20

25

30

35

40

0 50 100 150 200 250 300 350

stratified flow

annular flow

bubbly flow

wavy flowslug flow

NH3,totalO2,total

O2,water

O2,steam


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA



Single-phase flow- saturated- sub cooled

Bubbly flow

Slug flow

Annular flow with water entrainment

Drop flow

Single-phase steam flow

Pote

ntia

l for

flow

-acc

eler

ated

co

rrosio

nPotential for

cavitation erosion

Potential for droplet

impingement erosion

Combined effectspossible


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA



Flashing

Vapor bubbles form & remain

Cavitation

Vapor bubbles form & collapse

> Flashing - effect on FAC� Calculation of wall thinning taking into account the formation of vapor bubbles caused by flashing

� increase of flow velocity due� change in distribution of– oxygen and / or– alkalizing agent

in the water phase


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


>Water chemistry� pH value� oxygen concentration

> Material composition� chromium content� copper content� molybdenum content

> Thermal-hydraulics� relevant velocity� geometry and dimensions� fluid temperature� steam quality (void, flow pattern)

> Exposure / operating time

ChemistryOperation

Material

FAC


26AREVA NP

> AREVA NP Gm



IAEA



Cavitation erosion


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Cavitation Erosion- Introduction

> Cavitation erosion is a commonly experienced problem in power plants, causing serious wear and damage. Under specific conditions, cavitation will reduce the components life time dramatically.

> Cavitation may occur when the local static pressure in a fluid reaches a level below the vapor pressure of the liquid at the actual temperature. According to the Bernoulli Equation this may happen when the fluid accelerates e.g. in a control valve. The damage is not caused by vaporization itself, the damage rather occurs when the vapor spontaneously collapses at the inside wall of a pressure retaining structure.

28AREVA NP

> AREVA NP Gm



IAEA


Cavitation erosion-Mechanism

The degradation rate strongly depends on the intensity of jet formation.


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Cavitation erosion- Risk determination

For determining the basic risk due to cavitation erosion, a multi-parameter model is used, considering specific flow conditions for the respective element. The above diagram indicates the intensity of jet formation.

Temperature in °C

Depending on the expected severity of the jet formation and collapse intensity, the cavitation erosion model included with COMSY computes wall thinning rates for the individual material properties given.

30AREVA NP

> AREVA NP Gm



IAEA



Dropletimpingementerosion


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Droplet impingement erosion- Introduction

> Although all nuclear utilities have programs in place to protect against flow-accelerated corrosion (FAC), there has been only little effort to protect nuclear piping from droplet erosion damage> One of the most common forms of

erosion is liquid droplet impingement or droplet impingement erosion> This degradation mechanism

has caused wall loss, leaks, and ruptures and resulted in unplanned shutdowns in NPPs. Repair and replacement of damaged piping and equipment have been a continuing expense


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Droplet impingement erosion- Mechanism

Droplet

ImpactRadial flow

Normal and shear forces

Fracture in weakbrittle metal

Depression in ductile metal

Flow

Dropletimpingement

Area of highmetal loss

Water streaksdue to secondary flow

Secondary flowin a bend

Area of highmetal loss

Water film

Droplets


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Droplet impingement erosion- Sensibility

stratified flow

bubbly flow

wavy flow slug flow

annular flowCOMSY utilizes the modified Taitel & Dukler flow chart to reliably compute the individual flow regime for given system operation conditions and geometries. The flow chart model was validated using Benson® hydraulic test data.

Droplet impingement erosion is found only for annular/droplet flow regimes. Unfortunately, these flow regimes are commonly found in NPPs (main steam, extraction lines, drainage lines, venting lines etc.)


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Droplet impingement erosion - Influencing parameters (1)

Wall thinning

SteamQuality

10.8

0.60.4

00.2

> Classic droplet impingement erosion is found only in the region of droplet flow> In the annular flow

region an enhanced FAC wall thinning is induced by droplets


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA



> Degradation rates strongly correlate with flow velocity> Beyond a threshold

value, the degradation rate is negligible

Wall th

inning

Velocity0 20% 40% 60% 100%80%

Typicalsteam linesoperation

Drainage lines, pressurereduction systems


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA



Wall th

inning

Temperature0

Wall th

inning

Pressure0

The degradation rate due to droplet impingement erosion increases with temperature and pressure and reaches a maximum at approx. 300°C / 85 bar.


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA



The computation of wall thinning rates requires the knowledge of the specific material property strain work.In order to correctly resemble this parameter, a model which relates to commonly available parameters was developed.

0

X5 C

rNi1

8 10

Ck 4

5

GG

G 4

0

St 5

0-2

34 C

rNiM

o6

34 C

rNiM

o6

X22

CrNi

17

42 C

rMo

4

Material types

max.

Wall

thinn

ing ra

te Computed by COMSYExperimental results Material alloys and

strength properties significantly influence the evolution of wall thinning.


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA



Specifically vulnerable to droplet impingement erosion attacks are bends, tee-fittings, pipes behind offices or behind throttling valves.

The severity of wall thinning strongly depends on the individual system geometry.

p = 20.8 barT = 214.3°Cx = 0

p = 3.75 barT = 141.4°Cx = 0.1509

vVAPOR ≈ 220 m/s

39AREVA NP

> AREVA NP Gm



IAEA



Predictionof risk


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


1973 1975 1990 20001980 1985 1995 2005

COMSYCondition Oriented ageingand plant life Monitoring

SYstem

FAC-Model Update

FACtheoretical study and developmentof empirical model

Water flow experi-ments

Water flow experi-ments

WATHEC - development and application

DASY - development and application

COMSY development and application

Benson test facility

Flow-induced corrosion- history of FAC model development


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-accelerated corrosion- Model validation / verification / optimization

> Continuation of studies on FAC

> Collection of FAC cases for validation / optimization of the prediction model in a database

> Application of the model to BWRs (GE, ABB, KWU), PWRs(Westinghouse, KWU), VVERsand fossil-fired power plants (CCPP, coal-fired) worldwide

1975 1985 1995 2005year

0

10000

20000

30000

40000

50000

60000

FAC cases for validation

Kastnermodel

WATHECV 1.0

WATHECV 2.0

WATHECV 3.0

COMSYV 1.0

COMSYV 2.0


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-accelerated corrosion- Model validation / verification / optimization

> Uncertainties on wall thinning computation are considered via a safety margin in order to ensure safe operation of element.

> The computed wear is considered the maximum probable wall thinning rate for element under specified operating conditions. Hence, the corresponding recommended inspection date (RecUT) indicates the minimum life expectancy of the element.

wall t

hinnin

g rate

pred

icted

wall thinning rate measured

safety margin

>The safety margin is reduced after measurement results are available


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-accelerated corrosion- FAC prediction with COMSY

Obviously, a specifically designed software tool shall be used to consider all affecting parameters with a reasonable effort.


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-induced corrosion- COMSY characteristics

> COMSY copes with� the large number of parameters affecting flow-induced corrosion (FAC, droplet

impingement erosion and cavitation erosion) as well as� the complexity of their functional interdependencies.

> COMSY allows� the reliable identification of piping elements which may suffer material loss due

to FIC,� to calculate the minimum residual lifetime of piping elements affected by FIC to

streamline inspection effort and� to check countermeasures prior to their implementation.

COMSY is a proven and ready-to-use tool with user interfaces in different languages and provides common materials and stress calculation for various countries


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


COMSY – References

Philippsburg 1+2KrümmelIsar 1+2 BrunsbüttelBiblis A+BGundremmingen BBorsseleBeznau 1 GösgenLeibstadt Almaraz 1+2 Oskarshamn 3Forsmark 1+2 Fukushima 2-1Different fossil fired plantsOL3 lifetime design servicesChinshan 1

Spain : Asco 1+2 Almaraz 1+2CofrentesSt. Maria de Garona

Finland : Loviisa 1+2Hungary : Paks 1 to 4Bulgaria : Kozloduy 1 to 4Ukraine : Khmelnitski 1+2

Rowno 1 to 4Japan : Tomari 1+2 Brazil : Angra 1&2Belgium: 8 fossil fired plants

Service Applications Software Licenses

46AREVA NP

> AREVA NP Gm



IAEA



Countermeasures


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


> The establishment and implementation of an effective plant FAC program (e.g. using of a software tool) > Optimizing the water chemical treatment> Apply improved material concepts for replaced components or lines and/or sufficient wall thickness margins> Apply qualified repair technologies (e.g. METCO spraying, sheet metal cladding)

Flow-induced material degradation - Countermeasures

48AREVA NP

> AREVA NP Gm



IAEA


The six parameters form the columns of an effective FAC program.

Flow-induced material degradation -Effective plant FAC program


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-induced material degradation - Optimized water chemistry (1)

The pH value is one of the chief parameter affecting the FAC rate.To control the pH is important in that it provides a way of globally reducing the rate of FAC in power plants.High alkalizing levels reduce the FAC risk, but, are aggressive to copper.For copper – based materials like e.g. brass tubing of condensers or feedwaterheaters, a high pH values > 9.3 is not favorable, as it may accelerate wall thinning.


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


*Source: R. Freier, „Aqueous Solutions – Data for Inorganic and Organic Compounds, Vol.2”

Influence of pH on solubility of base material

The solubility of ferrous ions strongly depends on the pH-Value of the water phase. For ‘High-AVT’, that means a pH value of approx. 9.8, the solubility amounts to only 0.0274 mg/l.



The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Experience: KWU-PWR ‘Obrigheim‘ with High-AVT

Average value1 ppb

The plot indicate, that the iron ingress was reduced down to 1ppm after switching over from AVT water chemistry to High AVT treatment.

Experience: solubility of Fe on pH



The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Plant N: measured iron concentration dependence on the pH value in final feedwater

8,5

9

9,5

10

10,5

Jan 88 Sep 90 Jun 93 Mrz 96 Dez 98 Sep 01 Jun 04

pH-va

lue

0

2

4

6

8

Fefilt. [ppb]

pH(NH3)Fe

Average value: 0,6 ppb

Average value0.6 ppb



The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


8,5

9

9,5

10

10,5

Jan 76 Sep 78 Jun 81 Mrz 84 Dez 86 Sep 89 Jun 92 Mrz 95 Nov 97 Aug 00 Mai 03

pH-va

lue

0

5

10

15

20

Fefilt [ppb]

pH(NH3)Fe

Average value: 1 ppb

Average value1 ppb


Plant E: measured iron concentration dependence on the pH value in final feedwater


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-induced material degradation - Material concept (1)

The stability and solubility of the oxide layer is governed by the composition and amount of the alloying material (Cr, Mo, Cu) present.

The most beneficial alloying element is chromium. For steels with a Cr-content of 2.1% or more, FAC rates can be considered negligible.


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-induced material degradation - Material concept (2)

The results obtained from the AREVA – BENSON test rig represent the effect of different steel compositions on FAC rate.


The p

assin

g on,

as w

ell as

the c

opyin

g, dis

tributi

on an

d/or a

dapta

tion o

f this

docu

ment,

explo

itatio

n and

co

mmun

icatio

n of it

s con

tents

witho

ut ex

press

ed au

thoriz

ation

ispro

hibite

d. Co

ntrav

entio

n enta

ils lia

bility

for th

e pa

ymen

t of d

amag

es. A

ll righ

ts res

erved

in th

e eve

nt of

paten

t, utili

ty mo

del o

r orna

menta

l des

ign re

gistra

tion.

IAEA


Flow-induced material degradation - Repair technologies (1)

Welding material Application range

METCO spraying(2 layer)

ARC spraying(3 layer)

undercoating: Ni-Alprotective coating: Cr-Ni-Fe-Alloy

Inner surface of � turbine casing, � vessels,� heater,� large bore piping

Methode

1. Layer: Ni-Al2. Layer: Cr-Alloy3. Layer: Cr-Ni-Alloy

57AREVA NP

> AREVA NP Gm



IAEA


Repair with METCO flame spraying

Flow-induced material degradation -Repair technologies (2)

58AREVA NP

> AREVA NP Gm



IAEA


Repair with METCO flame spraying

Flow-induced material degradation -Repair technologies (3)

> areva np gmbh - atoms for peace and development · pdf fileareva np > areva np gmbh...

Documents