PWR Secondary Side Chemistry (November 2008) 1/ 49> Proprietary of AREVA NP GmbH Disclosure not permitted

The

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PWR Secondary Side Chemistry / Corrosion Control / Steam Generator Performance

PWR Secondary Side Chemistry (November 2008) 2/ 49> Proprietary of AREVA NP GmbH Disclosure not permitted

The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

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d/or

ada

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and

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Presentation Overview

> Basis for selection of water chemistry Field experience

Secondary side design & materials Key components

Steam Generator performance SG corrosion mechanism SG tube fouling

> Water chemistry measures for corrosion control Power Operation

Corrosion product control Oxygen control Impurity control

Annual outages> Conclusions

PWR Secondary Side Chemistry (November 2008) 3/ 49> Proprietary of AREVA NP GmbH Disclosure not permitted

The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

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and

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of it

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CONTROL

Water Chemistry SelectionFor Corrosion Control

Parameters to be considered for corrosion control:

Based on Field Experience Key Components should be the main target for corrosion control Steam Generators

PWR Secondary Side Chemistry (November 2008) 4/ 49> Proprietary of AREVA NP GmbH Disclosure not permitted

The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

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of th

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and

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utho

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Secondary Side SystemsDesign & Materials

(e.g. German Convoy Plant)

All carbon steel materialsExceptions:* SG tubes (I600; I800; I690TT; SS)* Condenser tubes (Cu bearing materials; SS; Ti)* FW HX; MSR (Cu; CS; SS)* Turbine blades (high alloyed steels)* Steam Extraction lines (Low alloyed steels)

PWR Secondary Side Chemistry (November 2008) 5/ 49> Proprietary of AREVA NP GmbH Disclosure not permitted

The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

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expl

oita

tion

and

com

mun

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ion

of it

s co

nten

ts w

ithou

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ress

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utho

rizat

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is

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d. C

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ion

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Steam Generator as KEY COMPONENTImportance of Good SG Performance

> World wide field experience confirm that SGs are the Key Components of PWRs:

SG reliability affects overall plant performance

Significant number of SGs experienced degradation problems Tube corrosion (mostly secondary side) Deterioration of primary to secondary heat transfer (Fouling)SG degradation problems force Unscheduled or extended outages, Preventive or corrective maintenance work Costly in terms of repair work, loss of power & radiation exposureMaintaining high SG performance means safe of money!

PWR Secondary Side Chemistry (November 2008) 6/ 49> Proprietary of AREVA NP GmbH Disclosure not permitted

The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

ptat

ion

of th

is d

ocum

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expl

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tion

and

com

mun

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ion

of it

s co

nten

ts w

ithou

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utho

rizat

ion

is

proh

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d. C

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vent

ion

enta

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Steam Generator as KEY COMPONENT World Wide SG Corrosion Problems

Source: EPRI SG Progress Report

0%

20%

40%

60%

80%

100%

73 75 77 79 81 83 85 87 89 91 93 95 97 99

Other Mechanisms

Wear

SCC OD

SCC ID

Pitting

Preventive(Mainly Denting)

Thinning(Wastage)

PWR Secondary Side Chemistry (November 2008) 7/ 49> Proprietary of AREVA NP GmbH Disclosure not permitted

The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

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Steam GeneratorCorrosion Mechanism

> SG corrosion is caused by concentrated impurities

In crevices (TSP: Tube Support Plate)Top of tube sheet

> Type of corrosion depends on chemical environmental conditions

Composition (pH)Redox potential

Location for impurity concentration

PWR Secondary Side Chemistry (November 2008) 8/ 49> Proprietary of AREVA NP GmbH Disclosure not permitted

The

pass

ing

on, a

s w

ell a

s th

e co

pyin

g, d

istri

butio

n an

d/or

ada

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