2007 10

FAC Flow Accelerated Corrosion

1

FAC

FAC

PWR FAC

FAC pH Cr

(FAC)

FAC Flow Accelerated Corrosion, Flow Assisted Corrosion FIC FlowInduced Corrosion

2

(FAC) 3

FAC

(FAC) 4

(FAC) 5

Fe3O4

pH

FAC Flow Accelerated Corrosion Flow Assisted Corrosion

(FAC) 6

2.1mm/Surry 21988/09

1mm/cycle(4 )Catawba 21991/11

6San Onofre 31990/07

8Millstone 21991/11

6Millstone 31990/07

Loviisa 21990/05

#1 14Sequoyah 11994/11

18Surry 21986/12

Callaway1999/08

4 12 5DFort Calhoun1997/04

14 7DTrojan1987/06

(FAC) 7

8FAC

Flow

Distance

Fe2+

Conc.

Metal(Fe)

Bulk water

Fe3O4Boundary layer

AVT (1)3Fe + 4H2O = Fe3O4 + 4H2 (1) ( )

Fe2+ (2)Fe3O4 + 2H2O + 2H+ + 2e- = 3Fe2+ + 6OH- (2)

Fe2+ FAC

dm/dt = (D/ ) Cs - Cbulk) = k Cs - Cbulk) (3)dm/dtD Fe2+

( )Cs Fe2+

Cbulk Fe2+

k D/

9(1/2)

10(2/2)

. ( )

275mm

:

45m/s

11

100(Hr)

<5DO2(ppm)

0 0.05, 0.1 0.2 0.35, 0.5N2H4(ppm)

8.9 9.2 9.5 9.8 10pHNH3

25 35 45(m/sec)

70, 100 150 190 220

Cr 0.02 0.25wt%Cr : 2.25wt%

12FAC

FAC

[FAC (mg/cm2/hr)] =

{[ ] – [ ]} { [ ]}

. ( )

( )

13–

FAC 100

FAC500

.

14–

. FAC

FAC

15–

. FAC

FAC 150

16– pH

FAC pHpH9.5

FAC1/10 1/20

FACpH

. FAC pH

17– N2H4

pH FAC N2H4 ppm

. FAC N2H4

18– Cr

Cr 2.25%FAC Cr

0.02% 1/20 1/50

CFAC

. FAC Cr

19FAC

FAC pH

FAC FAC

FAC

20(1/3)

( )

: (NH3, ETA, )

pH FAC FAC

pH

21(2/3)

AVT

Analytical Fe Conc.(ppb)

Calc

ulat

ed F

e Co

nc.(p

pb)

22(2/3)

(ppb)

0.5 12 34 6

1.00.62.14.8

ETANH3

pHETAAVT

23

FAC pH

FAC

PWR SG

SG

FAC

24(FAC)

O.Jonas,"Control Erosion/Corrosion of Steels in Wet Steam",Power, March, p102(1985)

180pH 7 9.5

<5ppb 500ppb20 m/s

pH7pH9.5 DO2 <5ppbpH7 DO2 <5ppb

FAC

FAC

18Cr StainlessFAC

25(FAC)

75pH 7

0 500ppb1.6 m/s

0.5 Mo1Cr-0.5Mo

120pH 7

0 500ppb35 m/s

FAC

FAC

(Fe2O3)

3

FAC

26(1/2)

FAC

FAC

FAC

FAC pH C

FAC 150FAC pH 0.6ppm

27(2/2)

FACFAC