化學除染工程이 304L 스테인레스강의 耐蝕性에 미치는...

304L

T h e In f lu en c e on Corro s ion Re s i s t an c e of 304L S t ain le s s

S te e l in Ch em ic al D e c ont am in ation P roc e s s e s

200 1 2

A b s tract

1

1.1

1.2

1.3

2

2 .1

2 .2

2 .3

2 .4

2.4.1 (Pitting Corrosion )

2.4.2 (Intergranular Corrosion )

3

3 .1 RCP

3.1.1 (KK)

3.1.2 (KKD)

3 .2

3.2.1

3.2.2

3.2.3

3 .3

3.3.1

3.3.2

3.3.3

3.3.4

3.3.5 pH (mV)

4 (K K )

4 .1

4 .2

4.2.1

4.2.2

4.2.3

4.2.4 2

4.2.5

4 .3

4.3.1 1.

4.3.2 2.

4.3.3 3.

4.3.4 4(, ).

4.3.5 5(, ).

4.3.6 6(, , ). (3, 5)

4.3.7 7.

4.3.8 8(, ).

4 .4

4.4.1

4.4.2

4.4.3

4.4.4

4.4.5

4 .5 pH

4 .6

4.6.1

4.6.2

4.6.3 pH ()

5 (K K D )

5 .1

5 .2

5.2.1 (65, 75, 85)

5.2.2 (65, 75, 85)

5 .3

5.3.1

5.3.2

5 .4

5.4.1

5.4.2

5.4.3

5.4.4

5.4.5

5 .5 pH (mV )

5.5.1 , , pH

5 .6

5.6.1 Ox alic Acid Citric Acid

5.6.2

5.6.3

5.6.4 pH

5 .7

5.7.1

5.7.2

5.7.3

5.7.4

5.7.5 pH (mV)

6

6 .1 (KK )

6 .2 (KKD )

T h e In f lu en c e on Corro s ion Re s i s t an c e of 304L S t ain le s s

S te e l in Chem ic al D e c ont am in at ion Proc e s s e s .

Y OU N G- HW A N , LE E

D epartm ent of M arin e E n g in e erin g

Gradu at e S choo l o f K ore a M arit im e U niv ers ity

A b s trac t

As an RCP (Reactor Coolant Pump) run in the nuclear power system for a long

time, it ' s surface is continuously contaminated by radioactive scales . In order to

perform regular or emergency repair about RCP internals, a special

decontamination process should be used to reduce the radiation from the RCP

surface by means of chemical cleaning .

From commercialization of nuclear power , most countries have taken interest in

decontamination process of nuclear power plant and tried to develop a proper

process . As result of that , nowdays, some countries have their own

decontamination process and don 't want open their technology to the pubic.

Because that , it is impossible to obtain skills about decontamination of foreign

country and it is necessarily to develop proper decontamination process system in

korea. So, on the base of skills about decontamination of foreign country which

was already opened in pubic KPS and our institute has developed two kinds of

decontamination process it self. One is KK(KEPCO KPS) process which is a

kind of concentrated chemical decontamination process, the other is KKD(KEPCO

KPS Dilute) process which is a kind of dilute chemical decontamination

process .

In general, the RCP internals are made of 304 stainless steel which can cause

a corrosion damage , such as intergranular corrosion or pitting corrosion , during

decontamination process . Because of that , we carried out various experiments

about corrosion damage on 304 stainless steel. In order to conform the proposed

process (KK and KKD process ), corrosion characteristics of stainless steel(RCP

matrial) have been studied by means of polarization test , weight loss

measurements, scanning electron microscope(SEM) investigation and pH and

potencial(mV) investigation in KK and KKD process .

1

1 .1

1980

.

.

,

.

(Reactor Coolant Pump, RCP )

(Steam Generator )

, 34 . RCP

,

. ,

RCP , ,

. RCP

. ,

.

RCP

, RCP

.1 )

RCP (304L Stainless Steel, ,

SUS304L) ,

(Inter - Granular Corrosion , IGC) (Pit ting )

,

.

RCP 1990

- 1 -

, , , ,

.2 )

. ,

.

1 .2

.

RCP

/ ,

.

RCP

, RCP

.

1 .3

RCP 304L

, ,

RCP(SUS304L) . (3, 4,

5) , , pH (mV ) /

, (Scanning Electon Microscope, SEM )

(Inter - Graular Corrosion , IGC) (Pitt ing )

.

,

.

- 2 -

2

2 .1

(Contamination )

, ,

(Decontamination ) .3 ) , , ,

, , , , ,

. Fig . 2.1

.

2 .2

(System Decontamination )

(Equipment Decontamination) ,

(Dilute Chemical Decontamination ) (Concentrated Chemical

Decontamination) .

,

RCS (Reactor Coolant System ),

(Plant ), RCS Sub- system .

, , (Steam Generator )

, RCP .

(1)

1) (Dilute Chemical Decontamination)

1%

CAN - DECON (Canada Decontamination ) .2 ) RCS

,

.

- 3 -

D econt amin ation

Electric al Chemic al M ech anic al

S oak ,

S crub

Circulation

in - s itu

Spray s , F oam s

Gels , Co ating s

Dilute

D econt amin ation

Concentrated

D econt amin ation

Le s s th an 1%

ty pic ally 0 .1 0 .3 %

M ore than 1%

ty pic ally 3 10%

F ig . 2 .1 D e c ont am in at ion m e th o ds

- 4 -

2) (Concentrated Chemical Decontamination )

110%( 3

7%) RCS RCP

, .

(2)

,

.3 ) 5 )

1) (Concentrated Chemical Decontamination )

AP (Alkaline Permanganate)

10% (Sodium Hydroxide) 3% (Potassium -

Permanganate) 80105 12/ (cycle) 12

. PWP (Pressurized Water Reactor )

, MnO2 10 pH .

0.0060.06/ hr , , (Inconel)

,

.

CIT ROX

CIT ROX 2.5% Oxalic Acid 5.0% Ammonium Citrate, 0.2% Ferric

Nitrate, 0.1% Diethylthiourea 85 14/

. AP .

Oxalic Aicd IGC

, .

CONAP (Concentrated Nitric Acid Permangante)

CONAP Westinghouse European Seavice Center RCP

. Semi- Concentrated Chemical Decontamination

3 24 . 1 RCP

10 2

, RCP .

- 5 -

2) (Dilute Chemical Decontamination )

AP (Alkaline Permanganate)

0.1% KMnO4 , 0.01% NaOH

90 618 .

.

NP (Nitric Permanganate)

KMnO4 HNO3 pH 2.53.5 93

46 . AP LOMI(Low

Oxidate Metal Ion ) .6 )

Sub- system .

LOMI(Low Oxidation State Metal Ion )6 )

197080 EPRI(Electric Pow er Research Institute)

. PWR, BWR

NP

CAN - DECON . ,

.

2 .3

(Stainless Steels )

11% . 30%

, 50% .

.

,

, , , , , , , ,

. 0.03%

1% .

(Ferrit ic),

(Martensit ic), (Austenitic), (Duplex)

- (Precipitation-Hardenable Alloys) .

RCP 300

- 6 -

T able 2.1 .7 ) 300

205275MPa 520760MPa,

4060% .

, (Cold Work)

.

(Heat - Affected Zone, HAZ) . SUS302, 304

, ,

. SUS321 347 SUS304

. SUS316L , ,

, SUS317L

. 304LN

.

,

.

2 .4

(Corrosion )

,

.

(Electrochemical Mechanism ) .

.8 )

(1) (Cell)

(2)

(3) (Eletrolyte)

- 7 -

T able 2 .1 Com po s it ion of s t andard au s t en it ic s t ainle s s s te e ls

T ypeUN S

No.

Com posit ion (% )

C Mn Si Cr Ni P S

201 S 20100 0.15 5.5- 7.5 1.00 16.0- 18.0 3.5- 5.5 0.06 0.03202 S 20200 0.15 7.5- 10.0 1.00 17.0- 19.0 4.0- 6.0 0.06 0.03205 S 20500 0.12- 0.25 14.0- 15.5 1.00 16.5- 18.0 1.0- 1.75 0.06 0.03301 S30100 0.15 2.0 1.00 16.0- 18.0 6.0- 8.0 0.045 0.03302 S30200 0.15 2.0 1.00 17.0- 19.0 8.0- 10.0 0.045 0.03

302B S30215 0.15 2.0 2.0- 3.0 17.0- 19.0 8.0- 10.0 0.045 0.03303 S30300 0.15 2.0 1.00 17.0- 19.0 8.0- 10.0 0.20 0.15

303S e S30323 0.15 2.0 1.00 17.0- 19.0 8.0- 10.0 0.20 0.06304 S30400 0.08 2.0 1.00 18.0- 10.0 8.0- 10.5 0.045 0.03

304H S30409 0.04- 0.10 2.0 1.00 18.0- 20.0 8.0- 10.5 0.045 0.03304L S30403 0.03 2.0 1.00 18.0- 20.0 8.0- 12.0 0.045 0.03

304LN S30453 0.03 2.0 1.00 18.0- 20.0 8.0- 12.0 0.045 0.03302Cu S30430 0.08 2.0 1.00 17.0- 19.0 8.0- 10.0 0.045 0.03304N S30451 0.08 2.0 1.00 18.0- 20.0 8.0- 10.5 0.045 0.03305 S30500 0.12 2.0 1.00 17.0- 19.0 10.5- 13.0 0.045 0.03308 S30800 0.08 2.0 1.00 19.0- 21.0 10.0- 12.0 0.045 0.03309 S30900 0.20 2.0 1.00 22.0- 24.0 12.0- 15.0 0.045 0.03

309S S30908 0.08 2.0 1.00 22.0- 24.0 12.0- 15.0 0.045 0.03310 S31000 0.25 2.0 1.50 24.0- 26.0 19.0- 22.0 0.045 0.03

310S S31008 0.08 2.0 1.50 24.0- 26.0 19.0- 22.0 0.045 0.03314 S31400 0.25 2.0 1.5- 3.0 23.0- 26.0 19.0- 22.0 0.045 0.03316 S31600 0.08 2.0 1.00 16.0- 18.0 10.0- 14.0 0.045 0.03

316F S31620 0.08 2.0 1.00 16.0- 18.0 10.0- 14.0 0.20 0.10316H S31609 0.04- 0.10 2.0 1.00 16.0- 18.0 10.0- 14.0 0.045 0.03316L S31603 0.03 2.0 1.00 16.0- 18.0 10.0- 14.0 0.045 0.03

316LN S31653 0.03 2.0 1.00 16.0- 18.0 10.0- 14.0 0.045 0.03316N S31651 0.08 2.0 1.00 16.0- 18.0 10.0- 14.0 0.045 0.03317 S31700 0.08 2.0 1.00 18.0- 20.0 11.0- 15.0 0.045 0.03

317L S31703 0.03 2.0 1.00 18.0- 20.0 11.0- 15.0 0.045 0.03321 S32100 0.08 2.0 1.00 17.0- 19.0 9.0- 12.0 0.045 0.03

321H S32109 0.04- 0.10 2.0 1.00 17.0- 19.0 9.0- 12.0 0.045 0.03330 N08330 0.08 2.0 0.75- 1.5 17.0- 20.0 34.0- 37.0 0.04 0.03347 S34700 0.08 2.0 1.00 17.0- 19.0 9.0- 13.0 0.045 0.03

347H S34709 0.04- 0.10 2.0 1.00 17.0- 19.0 9.0- 13.0 0.045 0.03348 S34800 0.08 2.0 1.00 17.0- 19.0 9.0- 13.0 0.045 0.03

348H S34809 0.04- 0.10 2.0 1.00 17.0- 19.0 9.0- 13.0 0.045 0.03384 S38400 0.08 2.0 1.00 15.0- 17.0 17.0- 19.0 0.045 0.03

- 8 -

(Electrolyte)

.

, (Organic Acid)

.9 )

2 .4 .1 (Pitting )

(Localized Corrosion)

. (Galvanic

Corrosion )

(Base Metal) .

. Fig . 2.2

, 4 .

(1) : Cell .

(2) : Pit

. ,

.

(3) : (Pit )

.

(4) :

. ,

.

2 .4 .2 (Interg ranular Corros ion )

.

.

,

- 9 -

F ig . 2 .2 D ia g ram m at ic repre s ent at ion of pitt in g

- 10 -

. Fig . 2.3 SUS304

. SUS304 ,

, .

SUS304 (Chromium - Depleted Regions)

.10 ) ,

BWR(Boiling Water Reactor ) ,

IGSCC(Inter - Granular Stress Corrosion Cracking )

.1 1 ) PWR(Pressurized Water Reactor )

.

, .

- 11 -

F ig . 2 .3 D iag ram m atic repre s e nt at ion of in t erg ranular c orro s ion

- 12 -

3

3 .1 R CP

H 2 ) ,3 )

. ,

.

3 .1.1 (Kepco & Kps , K K )

(KK )

, .

(KKD) , 2

.

(MKK)

.

Westinghouse European Service

Center RCP CONAP (Concentrated Nitric Acid

Permanganate) .2 ) Semi- Concentrated Chemical

Decontamiation 3 24

.12 )

(Pre- T reatment ) RCP

0.5% (NaOH) pH

10 8595 15 .

(Oxidation ) 34% (HNO3 ) 0.10.3% -

(KMnO4 ) 8595 30

. , (Dissolution ) 6368

5% (Oxalic Acid)

30. 3

Fig . 3.1 Flowchart .

- 13 -

F ig . 3 .1 F lo w ch art of K K m et h o d

1

: 15

: 30

: 30

2

: 15

4

: 30

: 30

3

: 15

5

: 30

: 30

- 14 -

T able 3 .1 RCP Ch e m ic al de c ont am in ation m o del in K K m et h o d

(g / L )

( )

(P re - T re at m e nt )NaOH 15 min . pH 10

(Ox idat ion )

HNO3 30 30 min . For pH control

KMnO4 3 30 min . For Cr3 + Cr6 +

(D i s s olu t ion )Oxalic Acid 30 30 min .

Citric

Acid(10g/ L)

85( 65)

- 15 -

35

RCP

.

3 .1.2 (Kepco & Kps Dilute , KKD )

2 ),

H .

.

NP (Nitric Permangnate) Citrox Process (Citric+Oxalic)

. NP Sub - sy stem

1,000ppm KMnO4 2,000ppm HNO3

pH 2.53.5 93 46 .

AP (Alkaline Permanganate) LOMI(Low Oxidate

Metal Ion) .6 ) . Citrox Process

Citric Acid Oxalic Acid 2:1 Dilute Citrox 0.25%

Steam Generator Channel Head, Reactor Recirculation Sy stem

, Oxalic Acid

.

, , ,

NP( ) Citrox () .

.

, KMnO4

.

.

(2): 4

(Decomposit ion ) (1)

( )

. Fig . 3.2 .

, .

- 16 -

F ig . 3 .2 F lo w c h art of K KD m e th o d

,

1

: 4

: 1

2

: 4

4

: 1

3

: 1

5

: 1

- 17 -

T able 3 .2 R CP ch em ic al de c ont am in ation m o del in K K D m e th od

(g / L ) ( )

(Ox idation )

HNO3 0.3151 cycle : 4 hour s

24cycle : 2 hour s

For pH control

KMnO4 0.600 For Cr 3 + Cr 6 +

(D e c om po s it ion )

HNO3 0.718

cycle : 1 hour For pH control

Oxalic Acid 0.923

(R e du c tion )

Oxalic Acid 0.602

cycle : 1 hour

For Reduction of

Fe, NiCitric Acid 1.564

LiOH 0.302 For pH control

85( : 65, 75, 85)

- 18 -

, .

,

,

. 90

, 65, 75, 85 .

3 .2

3 .2 .1

(1) (KK)

T able 3.3

. RCP SUS304L,

85

1, 1,

Oxalic Acid Citric Acid 1 . Fig . 3.3

SUS304L , AST M (G- 5)

. 1

. 2 , 2,000

, .13 )

(2) (KKD)

T able 3.4

. SUS304L

, 65, 75, 85 1

. ( Oxalic, Citric,

LiOH ) 1 5 .

.

- 19 -

T able 3 .3 T he conditions for polarization te s t specim ens in KK m ethod

(P re - T re atm ent )85

(Ox idat ion )

HNO3 (KMnO4 : 3g/ L )

HNO3 : 3g/ L HNO3 : 5g/ L HNO3 : 7.5g/ L

HNO3 : 10g/ L HNO3 : 20g/ L HNO3 : 30g/ L

KMnO4 (HNO3 : 7.5g/ L )

KMnO4 : 1g/ L KMnO4 : 2g/ L KMnO4 : 3g/ L

(D i s s olu t ion )Citric Acid (10g/ L) Oxalic Acid (30g/ L)

- 20 -

F ig . 3 .3 P olariz at ion t e s t s pe c im e n s

F ig . 3 .4 W eig ht lo s s s pe c im e n s (E x po s e d A re a : 100 )

- 21 -

T able 3.4 T he conditions for polarization te st specimens in KKD method

65 75 85

65 75 85

Setting 1 Sett ing 2 Setting 3

Setting 4 Sett ing 5

3 .2 .2

(1) (KK)

Fig . 3.4

15mm SUS304L 7070mm (100)

2mm .

RCP /

100( 1L) .

,

10- 4 g

. , ( ,

, ), (Oxalic Acid, Citric Acid),

(3, 4, 5 ), 1 . T able

3.5 .

(2) (KKD)

, ,

, . (65, 75, 85),

(100), (3, 4) . T able 3.6

.

- 22 -

T able 3 .5 T h e c on dit ion s f or w eig ht lo s s s pec im en s in KK m ethod

(W eig ht Lo s s )

(Ox idation )

HNO3 (KMnO4 : 3g/ L)

HNO3 : 3g/ L HNO3 : 5g/ L HNO3 : 7.5g/ L

HNO3 : 10g/ L HNO3 : 20g/ L HNO3 : 30g/ L

KMnO4 (HNO3 : 5g/ L)


KMnO4 (HNO3 : 7.5g/ L)


MnO4 (HNO3 : 10g/ L)

KMnO4 : 1g/ L KMnO4 : 2g/ L

3 4

HNO3 (3g/ L), KMnO4 (3g/ L)


HNO3 (7.5g/ L), KMnO4 (3g/ L)

(15min ) (30min) (45min)


HNO3 (10g/ L), KMnO4 (3g/ L)

HNO3 (30g/ L), KMnO4 (3g/ L)

HNO3 (7.5g/ L), KMnO4 (3g/ L)

HCl(30g/ L)

KMnO4 (3g/ L)

H2 SO4 (15g/ L)

KMnO4 (3g/ L)

(15)

HNO3 (30g/ L)

KMnO4 (3g/ L)

(D i s s olu t ion )Citric Acid (10g/ L) Oxalic Acid (30g/ L)

- 23 -

T able 3 .6 T he condition s f or w eig ht lo s s s pec im en s in KKD m ethod

(W eig ht L o s s )

65 (3 ) (4 )

75 (3 ) (4 )

85 (3 ) (4 )

3 .2 .3

(1) (KK)

Fig . 3.6

.

2,000 , .

.

T able 3.5 .

(2) (KKD)

,

. T able 3.7 (SEM)

.

- 24 -

F ig . 3 .6 S c annin g ele c tron m ic ro s c rope (S E M ) s pe c im en s

F ig . 3 .7 P olariz at ion t e s t k it

- 25 -

T able 3 .7 T h e c on dit ion s f or S E M s pe cim en s in K KD m e th o d

(S E M )

65 (3 ) (4 )

75 (3 ) (4 )

85 (3 ) (4 )

( )

- 26 -

3 .3

3 .3 .1

, , .

10 10

. RCP

100/ L .

RCP SUS304L

.

3 .3 .2

RCP

.

.14 ) ,15 ) (Working

Electrode, WE )

(Counter Electrode, CE ),

(Reference Electrode, RE ) .

Cyclic .

.

(1)

(Potentiostat )

(Potentiodynamic Method) .

(Open Circuit Potential) +1.0V , 5mV/ s

, AST M(G- 5) .

HNO3

- 27 -

.

(2) (Cyclic)

.

,

1 . 5mV/ s (O.C.P )

0.5V - 0.2V (vs . O.C.P ) .

(Ag v s . Ag/ AgCl).

/

(Potentiostat ), Fig . 3.7 Gamry CMS 100

. IBM

Window OS

.

AST M (G- 5) ,16 )

AST M .

3 .3 .3

.

. ,

3

5 .

3 .3 .4

RCP / SEM

.

2

.1 7 ) ,18 )

SEM (Scanning Electron Microscope) T EM (T ransmission Electron

- 28 -

Microscope) . SEM

, T EM

. T EM

.18 ) SEM .

SEM JEOL JSM - 5410 100,000

.

3 5

, . (50

350) ,

(1,200) .

3 .3 .5 pH (mV )

pH ORION pH Meter (Model:420A )

. pH

. ,

pH pH

.

, pH

pH .

, pH .

, .

- 29 -

4 (K K )

4 .1

RCP 2 ,

(out layer ) Fe2 O3 (Fe2 + ), Fe3O4 (FeO+ , Fe2 + , Fe3 + ), NiFe2 O4 (Ni2 + ,

Fe3 + ), (inner layer ) FeCr 2 O4 (Cr 3 +, Fe2 + ), NiCr2 O4 (Ni2 + ,Cr 3 +),

Cr 2O3 (Cr 3 + ) (crud) Fe1 .2Cr 1 .2Ni0 .6 O3

(M =212.6g/ mol), 3 5g/ .

(1) :

NaOH

. NaOH (pH10)

(2) : 30g/ L(HNO3 ) + 3g/ L(KMnO4 )

, KMnO4

.19 )

(outer layer ) : Fe2 + , Fe3 +,

Ni2 + , NO3 - .

HNO3 : 22HNO3 22H + + 22NO3 -

Fe2O3 : 6H + +Fe2O3 2Fe3 + + 3H2 O

Fe3O4 : 8H + + Fe3 O4 2Fe3 + + Fe2 ++ 4H2 O

NiFe2 O4 : 8H + + NiFe2 O4 Ni2 + + 2Fe3 + + 4H2O

(inner layer ) : K +, H + ,

CrO42 - , MnO42 - MnO2

Cr2 O3 :

6KMnO4 + Cr2 O3 + 5H2O 6MnO4 2 - + 2CrO42 - + 6K+ + 10H +

2KMnO4 + Cr2 O3 + H2O 2MnO2 + 2CrO4 2 - + 2K+ + 2H +

- 30 -

(3) : 10g/ L(Oxalic Acid) or 30g/ L(Citric Acid)

KMnO4 MnO2

Oxalic Acid KMnO4

MnO2 . 1 , ,

,

35 .

KMnO4 : 6H + + 2KMnO4 + 5C2 O4H2 (or C6 O7H8 )

2K2 + + 2Mn2 + + 10CO2 + 8H2 O

MnO2 : 2H+ + MnO2 + C2O4H2 (or C6O7H8 ) Mn2 + + 2CO2 + 2H2O

4 .2

, .

(OCP) - 0.05V 1.0V

, (Scan rate) 5mV/ s.

.

4 .2 .1

Fig . 4.1 (Pre- treatment ) 85o C (Sodium

Hydroxide) . pH 10

(- 0.30.6V )

, (

/ : 10- 5mA/ cm2, : 10- 5mA/ cm2) .

.

4 .2 .2 (HN O3 )

(HNO3 : 30g/ L, KMnO4 : 3g/ L)

. Fig . 4.2 (KMnO4 : 3g/ L)

- 31 -

(3, 5, 7.5, 10, 20, 30g/ L) ,

1 .

(Open Circuit Potential, OCP ) 1.17V

1.5V .

1.21.5V . 30 20

10g/ L .

10g/ L (3, 5, 7.5g/ L) .

3010g/ L 30g/ L

, (SEM )

. 10g/ L

,

()

.

4 .2 .3 (KM nO4 )

Fig . 4.3 (HNO3 : 7.5g/ L)

1 2 3g/ L .

(Fig . 4.2)

.

.

1.18V , 1.45V

. 1g/ L, 2g/ L

2g/ L

.

.

, .

4 .2.4 2 (3% Oxalic Acid, 1% Citiric Acid)

Fig . 4.4 . 1% Citiric

- 32 -

Acid , 3% Oxalic Acid

. 1% Citric

Acid 3% Oxalic Acid .

1% Citric Acid - 0.3V 3% Oxalic Acid

- 0.4V . 3% Oxalic

Acid

1% Citric Acid . 3% Oxalic Acid

.

4 .2 .5 (Cy clic )

Fig . 4.5 .

1.1V (O.C.P ) 0.5V

- 0.2V (vs . O.C.P) ,

.

4 .3

.

( )

.

.

.

4 .3 .1 1.

1

(Fig . 4.6).

. Fig . 4.6.ac 30 20 10g/ L

. 30g/ L 20g/ L

.

- 33 -

a. HNO3 : 30g/ L (oxidation process )

b . HNO3 : 20g/ L (oxidation process )

) T emp.: 85, ) Density : 100(SUS304L), ) 3 cycle

) T ime: 30min (15- 30- 30), ) Dissolution : Oxalic acid(30g/ L)

Fig . 4 .6 (I) SEM analy sis for different nitric acid solutions in ox idation proces s

- 34 -

c. HNO3 : 10g/ L (oxidation process )

d. HNO3 : 5g/ L (oxidation process )



Fig . 4 .6 ( ) SEM analy sis for different nitric acid solutions in ox idation proces s

- 35 -

e. HNO3 : 3g/ L (oxidation process )

f. HNO3 : 2g/ L (oxidation process )



Fig . 4 .6 ( ) SEM analy sis for different nitric acid solutions in ox idation proces s

- 36 -

. Fig . 4.6.df

52g/ L

.

.

.

.

4 .3 .2 2 .

2 (KMnO4 , HNO3 )

(Fig . 4.7). Fig . 4.7.b

. 30g/ L

.

,

.

Fig . 4.7.c (15o C) (30g/ L)

.20 ) Fig . 4.7. d, e

(HCl H2 SO4 ) . Fig . 4.7.d

(HCl) Cl-

.20 ) (H2 SO4 ) (Fig . 4.7.e)

(Intergranular Corrosion ) .

20 ) ,2 1 ),

.

2 2 )

.

- 37 -

a. Only HNO3 (30g/ L), without KMnO4 (3g/ L)

b . Only KMnO4 (3g/ L), without HNO3 (30g/ L)



F ig . 4 .7 ( ) S E M an aly s i s f or diff erent t re atm ent s in ox idation pro c e s s

- 38 -

c. Applied temperature : 15

d. HNO3 (30g/ L) change to HCl(30g/ L)

e. HNO3 (30g/ L) change to H2 SO4) T emp.: 85, ) Density : 100(SUS304L), ) 3 cycle


F ig . 4 .7 ( ) S E M an aly s i s f or dif f ere nt tre atm en t s in ox idat ion pro c e s s

- 39 -

4 .3 .3 3 .

3 .

(Fig . 4.8).

,

.

Fig . 4.8. af

.

mV/ s

.

1 2 2 3

.

4 .3 .4 4 ( , ) .

4(,) 3g/ L ,

7.5g/ L 10g/ L (15, 30, 45)

(Fig . 4.910). Fig . 4.9 a, b , c

5g/ L

. Fig . 4.10. ac 5g/ L 10g/ L 2

, .

Fig . 4.10.c(45) a, b . 4()

10g/ L 30

.

(

:10g/ L)

.

.

4 .3 .5 5 ( , ). (KMnO4 )

5(, ) ( 5(): 10g/ L, 5(): 5g/ L)

- 40 -

a. After oxidation process in 1 cycle(HNO3 : 30g/ L)

b . After dissolution process in 1 cycle(HNO3 : 30g/ L)



F ig . 4 .8 ( ) S E M an aly s i s f or e ac h cy cle an d pro c e s s

- 41 -

c. After oxidation process in 2 cycle(HNO3 : 30g/ L)

d. After dissolution process in 2 cycle(HNO3 : 30g/ L)




- 42 -

e. After oxidation process in 3 cycle(HNO3 : 30g/ L)

f. After dissolution process in 3 cycle(HNO3 : 30g/ L)




- 43 -

a. Oxidation process time: 15min. (HNO3 : 5g/ L)

b . Oxidation process time: 30min. (HNO3 : 5g/ L)

c. Oxidation process time: 45min. (HNO3 : 5g/ L)

) T emp.: 85, ) Density : 100(SUS304L), ) 3 cycle) T ime: 30min (15- 30- 30), ) Dissolution : Oxalic acid(30g/ L)

F ig . 4 .9 S E M an aly s i s f or diff erent t im e s in ox idat ion pro c e s s -

- 44 -

a. Oxidation process time: 15min. (HNO3 : 10g/ L)

b. Oxidation process time: 30min. (HNO3 : 10g/ L)

c. Oxidation process time: 45min. (HNO3 : 10g/ L)

) T emp.: 85, ) Density : 100(SUS304L), ) 3 cycle) T ime: 30min (15- 30- 30), ) Dissolution : Oxalic acid(30g/ L)

F ig . 4 .10 S E M an aly s i s f or dif f e re nt t im e s in ox idation pro c e s s -

- 45 -

(Fig . 4.1112). Fig . 4.11. a, b

12g/ L

. (10g/ L) 3g/ L

(Fig . 4.10.c) , .

5() (10g/ L) 1

2g/ L 3g/ L

. 4.6

3g/ L 1g/ L

. 5() 5g/ L

. Fig .

4.12. a, b 3g/ L 4g/ L

.

. 23 ),

304 ,

. RCP

( 1 3).

4 .3 .6 6 ( , , ) (3 , 5 )

6(, , )

(Fig . 4.1315).

6() 3g/ L, 3g/ L 3 5

. Fig . 4.13. a, b 3 5

. 6() 5g/ L

. Fig . 4.14. a, b 5 6()

hole .

. 6() 7.5g/ L .

Fig . 4.15. a, b 6() 5 3

, hole .

10g/ L 5

. RCP

- 46 -

a. KMnO4 (1g/ L), HNO3 (10g/ L)

b . KMnO4 (2g/ L), HNO3 (10g/ L)



F ig . 4 .1 1 S E M an aly s i s f or diff eren t pot a s s um - perm an a g at e s olu t ion s

in ox idat ion pro c e s s -

- 47 -

a. KMnO4 (3g/ L), HNO3 (5g/ L)

b . KMnO4 (4g/ L), HNO3 (5g/ L)



F ig . 4 .12 S E M an aly s i s f or diff eren t pot a s s um - perm an a g at e s olu t ion s

in ox idat ion pro c e s s -

- 48 -

a. 3 cycle (HNO3 : 3g/ L)

b . 5 cycle (HNO3 : 3g/ L)



F ig . 4 .13 S E M an aly s i s f or diff erent c y c le s in ox idation pro c e s s -

- 49 -

a. 3 cycle (HNO3 : 5g/ L)

b . 5 cycle (HNO3 : 5g/ L)



F ig . 4 .14 S E M an aly s i s f or diff erernt c y c le s in ox idation pro c e s s -

- 50 -

a. 3 cycle (HNO3 : 7.5g/ L)

b . 5 cycle (HNO3 : 7.5g/ L)



F ig . 4 .15 S E M an aly s i s f or dif f ere rn t cy c le s in ox idation pro c e s s -

- 51 -

, 5 RCP

.

4 .3 .7 7 . (7 .5g/ L )

(30g/ L)

. ,

.

.

7.5g/ L . 7.5g/ L

.

pH(pH : 12)

.

7 (7.5g/ L) (1, 2,

3g/ L) (Fig . 4.16). Fig . 4.16. ac

1g/ L 3g/ L

3g/ L .

3g/ L (Fig . 4.16.c) 2g/ L (Fig . 4.16.

b ) .

,

.

4 .3 .8 8

8 (7.5g/ L) 7

, (3 5) . 3

(Fig . 4.16) 5 (Fig . 4.17) 1 2 3g/ L

. Fig . 4.17.c

- 52 -

a. KMnO4 (1g/ L) (HNO3 : 7.5g/ L, 3cycle)

b . KMnO4 (2g/ L) (HNO3 : 7.5g/ L, 3cycle)

c. KMnO4 (3g/ L) (HNO3 : 7.5g/ L, 3cycle)

) T emp.:85C, ) Density : 100(SUS304L), ) 3 cycle) T ime: 30min (15- 30- 30), ) Dissolution : Oxalic acid(30g/ L)

F ig . 4 .16 S E M am aly s i s f or diff erent pot a s ium - perm an at e s olu t ion sw ith m o dif ie d n itric a c id s olu t ion in ox idat ion pro c e s s -

- 53 -

, , hole .

7.5g/ L 3g/ L ,

5 .

.

4 .4

RCP .

,

.

. ,

.

4 .4 .1

T able 4.1 (3g/ L) (302g/ L)

.

. 3020g/ L

0.020g 107.5g/ L 1/ 4 0.005g

. 5g/ L

0.002g .

5g/ L

.

4 .4 .2

5, 7.5, 10g/ L

. T able 4.2

- 54 -

a. KMnO4 (1g/ L) (HNO3 : 7.5g/ L, 5cycle)

b . KMnO4 (2g/ L) (HNO3 : 7.5g/ L, 5cycle)

c. KMnO4 (3g/ L) (HNO3 : 7.5g/ L, 5cycle)

) T emp.: 85C, ) Density : 100(SUS304L), ) 5 cycle) T ime: 30min (15- 30- 30), ) Dissolution : Oxalic acid(30g/ L)

F ig . 4 .17 S E M am aly s i s f or diff erent pot a s ium - perm an at e s olu t ion s

w ith m o dif ie d n itric a c id s olu t ion in ox idat ion pro c e s s -

- 55 -

T able 4 .1 Com pari s on of w e ig ht lo s s in v ariou s n itric a c id s olu t ion s

(g / L )

HNO3

(30g/ L)

HNO3

(20g/ L)

HNO3

(10g/ L)

HNO3

(7.5g/ L)

HNO3

(5g/ L)

HNO3

(3g/ L)

HNO3

(2g/ L)

(g ) 55.5107 55.7365 55.8998 54.2333 55.7368 53.6979 54.3369

(g ) 55.4497 55.7164 55.8950 54.2297 55.7345 53.6960 54.3351

(g ) 0.0520 0.0200 0.0048 0.0036 0.0023 0.0019 0.0018

- 56 -

.

5g/ L 4g/ L 3g/ L

, 2g/ L .

,

. 7.5g/ L

. 10g/ L

5g/ L

.

, (: 5g/ L, 10g/ L)

.

4 .4 .3

T able 4.3 3 5

.

(3g/ L : 0.0190 0.1130g, 5g/ L :

0.0025 0.0029g ) 7.5g/ L 3

0.0036g, 5 0.0066g .

.

.

4 .4 .4

T able 4.4

.

50%, 100% .

5g/ L 45 0.0011 0.0044g

. 30g/ L 15, 30

.

- 57 -

T able 4 .2 Comparison of w eight los s in v arious potas sium - permag anate solutions

(g / L )

HNO3 (5g/ L) HNO3 (7.5g/ L) HNO3 (10g/ L)

KMnO

(2g/ L)

KMnO

(3g/ L)

KMnO

(4g/ L)

KMnO

(1g/ L)

KMnO

(2g/ L)

KMnO

(3g/ L)

KMnO

(1g/ L)

KMnO

(2g/ L)

55.8186 55.7368 55.4163 53.4687 54.5819 55.7368 55.8853 55.4142

55.8119 55.7345 55.4112 53.4667 54.5792 55.7345 55.8812 55.4112

0.0067 0.0023 0.0051 0.0020 0.0027 0.0023 0.0041 0.0030

- 58 -

T able 4 .3 Com pari s on of w eig ht lo s s at t w o c y c le s

HNO3 (3g/ L)

KMnO4 (3g/ L)

HNO3 (5g/ L)

KMnO4 (3g/ L)

HNO3 (7.5g/ L)

KMnO4 (3g/ L)

3 cycle 5 cycle 3 cycle 5 cycle 3 cycle 5 cycle

53.6979 53.6952 54.9772 55.7678 54.2333 54.1665

53.6960 53.6562 54.9697 55.7649 54.2297 54.1599

0.0019 0.0030 0.0025 0.0029 0.0036 0.0066

- 59 -

(Fig . 4.4 10g/ L)

.

4 .4 .5

T able 4.5

.

.

Fig . 4.7.d

. Fig . 4.7.e

. ,

.

T able 4.4(: 15o C) T able 4.5(85o C)

. 30g/ L 85o C 0.00470.0058g

, 15o C

(0.0030g ) .

.

T able 4.5 (, )

.

0.0070g ,

+0.0007g .

.

,

,

, ,

.

- 60 -

T able 4 .4 Com pari s on of w e ig ht lo s s w ith v ariou s t im e of ox idat ion s

HNO3 (5g/ L)

KMnO4 (3g/ L)

HNO3 (10g/ L)

KMnO4 (3g/ L)

HNO3 (30g/ L)

KMnO4 (3g/ L)

15min 30min 45min 15min 30min 45min15min

(304L)

30min

(304L)

(g ) 55.7906 55.6186 55.5165 55.7865 55,9028 55.8401 55.8141 55.5107

(g ) 55.7884 55.6715 55.5142 55.7855 55.9000 55.8357 55.7670 55.4497

(g ) 0.0012 0.0011 0.0023 0.0011 0.0028 0.0044 0.0471 0.0520

- 61 -

T able 4 .5 Com pari s on of w eig ht lo s s at a ddit ion al dif f ere nt c on dit ion s

( 85 C )

HCl(30g/ L)

KMnO4 (3g/ L)

H2SO4 (15g/ L)

KMnO4 (3g/ L)

(15)

HNO3 (30g/ L)

KMnO4 (3g/ L)

HNO3

(30g/ L)

KMnO4

(3g/ L)

54.3267 55.5519 55.7059 55.4500 55.5410

54.3058 55.5087 55.7029 55.4431 55.5417

0.0210 0.0430 0.0030 0.0070 +0.0007

- 62 -

4 .5 pH

T able 4.67 pH . T able 4.6

pH .

pH .

T able 4 .6 Com pari s on of pH in diff eren t n itric a c id s olu t ion s

pH (m V ) (KM n O4 :3g / L , :85 )

HNO3

(30g/ L)

HNO3

(20g/ L)

HNO3

(10g/ L)

HNO3

(7.5g/ L)

HNO3

(5g/ L)

HNO3

(3g/ L)

HNO3

(2g/ L)

pH 0.61 0.80 1.08 1.15 1.11 1.60 2.10

T able 4.7 pH .

pH .

pH .

T able 4 .7 Com pari s on of pH in dif f e rent c on dit ion s

pH (m V ) ( :8 5 )

HNO3 (10g/ L) HNO3 (7.5g/ L)HNO3

(5g/ L)

KMnO4

(1g/ L)

KMnO4

(2g/ L)

KMnO4

(1g/ L)

KMnO4

(2g/ L)

KMnO4

(4g/ L)

Oxalic

(30g/ L)

Citric

(10g/ L)

pH 1.11 1.18 1.40 1.41 1.74 1.18 1.32

- 63 -

4 .6 (M K K )

,

. ,

.

4 .6 .1

(1)

, ()

(HNO3 ) 22HNO3 22H + 22NO3 -

(Fe2 O3 ) 6H + Fe2 O3 2Fe3 + 3H2O

(Fe3 O4 ) 8H + Fe3 O4 Fe2 + 2Fe3 + 4H2O

(NiFe2O4 ) 8H+ NiFe2O4 Ni2 + 2Fe3 + 4H2O

T otal : 22HNO3Fe2 O3Fe3 O4NiFe2 O4

Fe2 +6Fe3 +Ni2 +22NO3 - 11H2 O

, HNO3

(Fe2 O3 ) 120g (180g ) 0.7519M (1.1278M ),

4.511M (6.767M ).

60g 0.2561M, 2.049 M.

6.768.82M,

413556g. 2,000L 0.210.28g/ L ,

(Safe Factor ) 100% 0.420.56g/ L .

()

(Cr2 O3 ) 2KMnO4Cr 2O3H2 O 2MnO22CrO42 - 2K+2H +

(HNO3 ) 4HNO3 4H + 4NO3 -

(Cr2 O3 ) 6H + Cr2 O3 2Cr 3 + 3H2O

Total : 2KMnO42Cr2 O34HNO3

2MnO22CrO42 - 4K+4NO3 - 2Cr3 +2H2 O

- 64 -

HNO3 KMnO4

HNO3 : 120g 0.7895M,

(total) 1.579M, 99.477g. 2,000L

0.0497g/ L , (safe factor ) 100%

0.10g/ L .

KMnO4 : 0.7895M

(T otal) 0.7895M, 124.74g. 2000L

0.0624g/ L , (safe factor ) 100%

0.13g/ L .

HNO3 : , HNO3

0.420.56g/ L HNO3 0.10g/ L

, HNO3 0.50.7g/ L

.

KMnO4 : , KMnO4

KMnO4 0.13g/ L

.

: 0.50.7g/ L

30g/ L . 40

. 4.3.7

57g/ L .

0.13g/ L 20 3g/ L

, . 4.3.7

1g/ L .

(2)

()

(HNO3 ) 10HNO3 10H + 10NO3 -

(KMnO4 ) 6H+2KMnO45C2O4H2 2K+2Mn2 +10CO28H2O

(MnO2 ) 4H +2MnO22C2O4H2 2Mn2 +4CO24H2 O

- 65 -

Total : 2KMnO42MnO210HNO37C2O4H2

2K+4Mn2 +10NO3 - 14CO212H2O

HNO3

, 1g/ L(0.6g/ L)

. 1g/ L(0.6g/ L) 50% 80%

, 0.8g/ L (0.48g/ L)

0.14g/ L (0.083g/ L) .

1g/ L (0.6g/ L) 2.0g/ L (1.2g/ L).

C2O4H2

1.4g/ L (0.84g/ L). 100% 2.8g/ L(1.7g/ L) .

,

. Fig .

4.6, 8 HNO3

. T able 4.8

HNO3 30g/ L 6g/ L . Fig . 4.11 12

KMnO4 3g/ L 1g/ L

.

.

Oxalic Acid 2g/ L .

HNO3 KMnO4

.

Oxalic Acid, Citric Acid, LiOH

.

pH (pH =2.5)

. pH LiOH pH 2.0

3.0. 85,

30, 60, 90

. .

- 66 -

T able 4 .8 D e c on t am in ation m o de l in t h e b e s t s u it e d K K m eth o d

(g / L )1 2 3 4 5

(Ox idat ion )

HNO3 6.3 6.3 6.3 6.3 6.5 pH pH

12

.

pH 1.5KMnO4 1 1 1 1 1

(D e c om po s it ion )

Oxalic

Acid2 2 2 2 2

(R e du c tion )

Oxalic

Acid0.7 0.3 0.1 0.1 0.1

pH pH

23

.

pH 2.5

Citric

Acid1.4 1.0 0.7 0.7 0.7

LiOH 1.5 1.4 1.25 1.25 1.25

30, 60, 90

- 67 -

4 .6 .2

(1) 30

Fig . 4.18 3, 4, 5 30 .

3, 4(Fig . 4.18. a, b ) 5

. 30 3, 4

, 5

30 . 5

.

(2) 60

Fig . 4.19 3, 4, 5 60 .

.

30 3 (Fig . 4.19.a)

, 4 (Fig . 4.19.b) .

5 (Fig . 4.19.c) 30

. 60 3, 4

, 5 .

(3) 90

Fig . 4.20 3, 4, 5 90 .

, 5 ,

(Fig . 4.20.e) . 3

30 , 60 90

. 4 (Fig . 4.13.b)

60 4

. 4

30 90

. 5 (Fig . 4.20. c, d, e) 60

- 68 -

a . 3 cycle

b . 4 cycle

c. 5 cycle

) T emp.: 85C, ) Density : 100, iii) T ime: each process 30min .

Fig . 4 .18 S EM analy s is for diff erent cy cle in 30 minute proces s (ox id - dis s - red)

- 69 -

a. 3 cycle

b . 4 cycle

c. 5 cycle


Fig . 4 .19 S EM analy s is for diff erent cy cle in 60 minute proces s (ox id - dis s - red)

- 70 -

a. 3 cycle

b . 4 cycle

c. 5 cycle


Fig . 4 .20 ( ) SEM analy sis for different cy cle in 90 minute process (ox id- dis s - red)

- 71 -

d. 5cy cle - 1

e. 5 cycle - 2


Fig . 4 .20 ( ) SEM analy sis for different cy cle in 90 minute process (ox id- dis s - red)

- 72 -

a . Applied time : 30min. (30- 30- 30)

b . Applied time : 60min . (60- 60- 60)

c. Applied time : 90min . (90- 90- 90)

) T emp.: 85C, ) Density : 100, iii) 3 cycle

Fig . 4 .21 Comparison of SEM analy sis for different time proces s (30 , 60 & 90 min )

- 73 -

(Fig . 4.20.e)

. 5 30

60, 90 .

4 .6 .3 pH ( )

T able 4.912 pH .

30 3 : 0.0035g (T able 4.9, : 100), 4 :

0.0040g, 5 : 0.0041g 4, 5

(T able. 4. 10) 30 3, 4, 5

(4. 6. 2. 30

) 0.00300.0040g

. 60 3 : 0.0046g (T able 4.9 ), 4 :0.0039g

5 0.0063g (T able 4.11). SEM

30 3, 4 , 5

. 90 3 (0.0043g)

, 4 (0.0065g) 5 (0.0073g)

(T able. 4.12). 90 3 4, 5

. pH

T able 4.1012 .

pH :1.671.70 , pH:1.75

1.85, pH :2.352.40 .

.

T able 4 .9 Comparis on of w eig ht los s at different proces s times

30

(30 - 30 - 30 )

3

6 0

(6 0 - 6 0 - 6 0 )

3

90

(90 - 90 - 90 )

3

(g ) 57.8981 57.6602 57.6108

(g ) 57.8946 57.6556 57.6065

(g ) 0.0035 0.0046 0.0043

- 74 -

T able 4 .10 Result s of w eig ht los s , temp . & pH in 30 minute proces s

1

pH ( ) 1.64 1.76 2.31 (331.9mV )

( C ) 84 85 83

2

pH ( ) 1.67 1.83 2.34 (333.6mV )

( C ) 82 84 83

3

pH ( ) 1.68 1.84 2.28 (335.7mV )

( C ) 82 84 85

4

pH ( ) 1.70 1.83 2.31 (333.4mV )

( C ) 83 84 82

5

pH ( ) 1.67 1.80 2.27 (337.6mV )

( C ) 86 85 83

4 : 55.7637g ( ) 55.7597g ( ) : 0.0040g

5 : 55.9352g ( ) 55.9311g ( ) : 0.0041g

- 75 -


1

pH ( ) 1.63 1.75 2.35 (328.8mV )

( C ) 82 82 82

2

pH ( ) 1.69 1.82 2.35 (327.4mV )

( C ) 82 82 83

3

pH ( ) 1.68 1.81 2.28 (330.8mV )

( C ) 83 81 82

4

pH ( ) 1.71 1.83 2.23 (337.2mV )

( C ) 84 84 82

5

pH ( ) 1.69 1.82 2.31 (331mV )

( C ) 84 82 84

4 : 54.3323g ( ) 54.3284g ( ) : 0.0039g

5 : 56.1917g ( ) 56.1854g ( ) : 0.0063g

- 76 -


1

pH ( ) 1.63 1.74 2.37 (328.8mV )

( C ) 83 83 84

2

pH ( ) 1.67 1.81 2.48 (319.4mV )

( C ) 83 82 83

3

pH ( ) 1.70 1.85 2.40 (325.5mV )

( C ) 82 83 83

4

pH ( ) 1.71 1.85 2.41 (327.2mV )

( C ) 82 83 85

5

pH ( ) 1.73 1.85 2.33 (330mV)

( C ) 83 85 83

4 : 57.9325g ( ) 57.9260g ( ) : 0.0065g

5 : 56.6943g ( ) 57.6870g ( ) : 0.0073g

- 77 -

5 (Kepco & Kps Dilute )

5 .1

(1) : 0.315g/ L (HNO3 ) + 0.6g/ L(KMnO4 )

clud

(outer layer )

HNO3 : 22HNO3 22H + + 22NO3 -

Fe2 O3 : 6H + + Fe2O3 2Fe3 + + 3H2 O

Fe3 O4 : 8H + + Fe3O4 Fe2 + + 2Fe3 + + 4H2 O

NiFe2 O4 : 8H + +NiFe2O4 Ni2 + + 2Fe3 + + 4H2 O

outer layer clud Fe2 + , Fe3 + , Ni2 +, NO3 -

.

(inner layer )

Cr 2 O3 :

6KMnO4 + Cr 2O3 + 5H2 O 6MnO42 - + 2CrO4 2 - + 6K+ + 10H +

2KMnO4 + Cr 2O3 + H2 O 2MnO2 + 2CrO4 2 - + 2K + + 2H +

K+ , H + , CrO4 2 - , MnO4 2 -

MnO2 .

(2) : 0.718g/ L (HNO3 ) + 0.923g/ L (Oxalic Acid: C2 O4H2 )

KMnO4 MnO2

HNO3 : 8HNO3 8H + + 8NO3 -

KMnO4 :

6H + + 2KMnO4 + 5C2 O4H2 2K+ + 2Mn2 + + 10CO2 + 8H2 O

MnO2 : 2H+ + MnO2 + C2O4H2 Mn2 + +2CO2 + 2H2O

KMnO4 MnO2 K +, Mn2 +, NO3 -

CO2 .

- 78 -

(3) : 0.602g/ L(C2O4H2 ) + 1.564g/ L(C6O7H8 ) + 0.302g/ L(LiOH)

1 Oxalic Acid

Citric Acid

:

, RCP

.

(free radical(H +)) .

Oxalic Acid : 3.5C2 O4H2 7H + + 7CO2

Citric Acid : 5C6 O7H8 15H + + 15CO2 + 5C3 OH5

Fe2 O3 : 6H + + Fe2 O3 2Fe2 + (free radical) + 3H2O

Fe3 O4 : 8H + + Fe3 O4 3Fe2 + (free radical) + 4H2O

NiFe2 O4 : 8H + + NiFe2O4 Ni2 + + 2Fe3 + + 4H2 O

Fe3 + Fe2 + ,

Oxalic Acid Citric Acid CO2 .

(4) LiOH

LiOH

Oxalic Acid Citric Acid LiOH

pH , Oxalic

Acid Citric Acid LiOH .

) O.A . : (COOH )2LiOH C2O4HLi H2 O

(COOH )22LiOH (COOLi)2 2H2 O

) C.A . : C6O7H8LiOH C6O7H7Li H2O

C6O7H82LiOH C6 O7H6Li2 2H2 O

C6O7H83LiOH C6 O7H5Li3 3H2 O

) O.A . : (COOH )24OH - C2H4 (OH )2 3O2

4(COOH )2 C2H4 (OH )2 6CO2 2OH -

(COOH )26OH - 2CH3 OH 4O2

- 79 -

) C.A . : 11C6O7H816OH - 13C3H5 (OH )3 27CO2

) Oxalic Acid 126 Citric Acid. 210 LiOH

24.

) 0.602g/ L, 1.564g/ L, 0.302g/ L Oxalic, Citric Acid, LiOH

4.78M, 7.45M, 12.58M

) Citric Acid Oxalic Acid 1.43

1.56.

) LiOH Oxalic Acid Citric Acid

13 .

) LiOH 4.78M, 0.115g/ L

7.453=22.35M, 0.536 g/ L.

LiOH

) LiOH 0.302g/ L 2.6

.

) LiOH

.

5 .2

.

5 .2 .1 (65 , 75 , 85 )

Fig . 5.1

,

. 1.0V ,

1.2V 75 65, 85 (A/ )

. 1.2V

.

- 80 -

5 .2 .2 (65 , 75 , 85 )

Fig . 5.2 ,

. 65 75

( 0.1V) ,

(A/ ) , 85

. 85

.

5 .3

5 .3 .1

85 .

85 (Fig . 5.5) .

80

.

1989 Chalk River

2 4 ) Citric Acid Oxalic Acid

410SS 117 90 117

630 . 117

Fe2 +

. 85

.

RCP 90

85

.

5 .3 .2

4 3

(Fig . 5.35.5 ab). 4 3

- 81 -

(a ) 65, 100, 3cycle

(b ) 65, 100, 4cycle

F ig . 5 .3 S E M an aly s i s w it h diff erent c on dit ion s ( )

- 82 -

(a ) 75, 100, 3cycle

(b ) 75, 100, 4cycle


- 83 -

(a ) 85, 100, 3cycle

(b ) 85, 100, 4cycle


- 84 -

3 . 3

4

3 . 3

.

5 .4

5 .4 .1

,

.

,

.

.

5 .4 .2

T able 5.1 .

90

, 65, 75, 85 ,

RCP /

100(1L)

5 .4 .3

T able 5.2 . 0.0004

0.0018g .

- 85 -

T able 5 .1 Comparis on of w eig ht lo s s at diff erent condition s

65 7 5 85

355.8697 55.7130 55.7823

55.8688 55.7126 55.7814

455.9319 55.7903 56.0127

55.9302 55.7881 56.0118

5 .4 .4

T able 5.2 3, 4 65 0.0026g, 75

0.0022g, 85 0.0018g. 3

65: 0.0009g, 75: 0.0004g 85 0.0009g. 75

65, 85 . 4

0.0017g, 0.0018g, 0.0009g .

65 75 , 85

. Fig . 5.1

. ,

.

T able 5 .2 R e s u lt s of w e ig ht lo s s in diff erentc on dit ion s in K K D m eth o d

65 75 8 5

3 0.0009 0.0004 0.0009 0.0022

4 0.0017 0.0018 0.0009 0.0044

0.0026 0.0022 0.0018

- 86 -

5 .4 .5

T able 5.2 3 4

4 3 . , 3

0.0022g 4 0.0044g.

65 0.0008g, 75

0.0014g, 85 .

34

. 3

.

5 .5 pH (m V )

5 .5 .1 , , pH (m V )

T able 5.3 pH .

4 3

pH 2.672.82, 3.233.35.

pH 4%

pH .

pH 2.70,

2.77, 3.29

. ,

pH ,

. pH ,

, , KMnO4

H+ HNO3 pH

(4.1 ). Table 5.3

65 225.7mV, 75 232.7mV, 85

240.6mV .

- 87 -

T able 5 .3 Comparison of pH at the each process with different temperatures and cycles

65 ( :225 .7m V ) 75 ( :232 .7m V ) 85 ( :24 0 .6m V )

1 2 3 4 1 2 3 4 1 2 3 4 ()

2.86 2.71 2.68 2.42 2.67 2.75 2.73 2.69 2.75 2.73 2.70 2.80 2.65 2.73 2.72 2.70

2.95 2.68 2.78 2.72 2.78 2.44 2.72 2.83 2.88 2.72 2.85 2.75 2.78 2.89 2.82 2.77

3.13 3.29 3.32 3.19 3.23 3.45 3.38 3.34 3.23 3.35 3.26 3.33 3.32 3.19 3.28 3.29

- 88 -

5 .6 (K K D )

5 .6 .1 Ox alic Acid Citric Acid

Oxalic Acid Citric

Acid

.

.

, .

(1) Citric Acid Oxalic Acid

: Oxalic Acid Citric Acid 3.55,

.

: Oxalic Acid Citric Acid

, Oxalic Acid 126, Citric Acid

210. , Oxalic Acid

Citric Acid 0.602 1.564g/ L , 4.778 7.448

, 3.5 5.456 .

: 3.5 5 3.5

5.456. Oxalic Acid Citric Acid

. Citric Acid Oxalic Acid

.

T able 5.4 3

. Oxalic Acid Citric Acid

,

. Oxalic, Citric

Acid , ,

H + Oxalic Acid , , H +

90% Oxalic Acid 10% Citric Acid ,

80% Oxalic Acid 20% Citric Acid

- 89 -

T able 5 .4 Decontamination model in reduction proces s

w ith different ox alic , citric acid solutions

(g / L )

HNO3 0.315

KMnO4 0.6

HNO3 0.718

Oxalic Acid 0.923

Oxalic Acid: 100%Oxalic Acid: 90%

Citric Acid: 10%

Oxalic Acid: 80%

Citric Acid: 20%

Oxalic Acid 1.3 1.225 1.155

Citric Acid 0 0.157 0.012

LiOH 0.302

: 85C, : 100, : 3cycle

- 90 -

. Oxalic Acid Citric Acid T able 5.4

. 85, 100,

3 2 .

5 .6 .2

1 3 . Fig . 5.6

. 2 (Fig . 5.7) , Oxalic Acid

(Fig . 5.7.c) Oxalic Acid(90%)

Citric Acid(10%) (Fig . 5.7.b)

. 1, 2 , 3

Oxalic Acid .

Citric Acid ,

Oxalic Acid .

5 .6 .3

T able 5.5 . Oxalic

Acid Oxalic Acid(90%) Citric Acid(10%)

0.0020g , Oxalic Acid(80%) Citric Acid(20%)

0.0014g 0.0006g

. ,

(T able 3.2) 0.0010g0.0020g.

T able 5 .5 Com pari s on of w eig ht lo s s w ith diff erent ox alic , c itrica c id s olu t ion s in re du ct ion pro c e s s

Ox alic Acid: 100%Ox alic Acid: 90%

Citric Acid: 10%

Ox alic Acid: 80%

Citric Acid: 20%

(g ) 56.8119 55.8031 55.9082

(g ) 56.8099 55.8011 55.9068

(g ) 0.0020 0.0020 0.0014

- 91 -

a. Oxalic Acid: 80% , Citric Acid: 20%

b. Oxalic Acid: 90% , Citric Acid: 10%

c. Oxalic Acid: 100%

F ig . 5 .6 S E M analy s i s at diff e rent s olut ion s in re du ction pro c e s s -

- 92 -

a. Oxalic Acid: 80% , Citric Acid: 20%

b. Oxalic Acid: 90% , Citric Acid: 10%

c. Oxalic Acid: 100%

F ig . 5 .7 S E M analy s i s at diff e rent s olut ion s in re du ction pro c e s s -

- 93 -

5 .6 .4 pH

T able 5.6 pH . 30

pH , pH

T able 5.6 pH .

T able 5 .6 Com pari s on of pH w ith ox alic an d cit ric ac ids olu t ion s in re du c tion pro c e s s

Ox alic A cid: 100%Ox alic Acid: 90%

Citric Acid: 10%

Ox alic Acid: 80%

Citric A cid: 20%

1 3.17 3.20 3.15

2 3.19 3.18 3.21

3 3.17 3.20 3.26

5 .7 (K K D )

5 .7 .1

.

,

. pH

, pH

.

.

,

, pH .

5 .7 .2

T able 5.7 ( , , ) .

- 94 -

(Oxalic Acid, Citric Acid)

, 5 (Setting 15) 2 . Fig 5.8

Settting

. Sett ing (OCP)

- 0.5V , OCP - 0.1V Setting

. Setting 24

, Setting 1 5

. Setting 1 Setting 5

, Setting 5 OCP -

. Setting 1, 5 Setting

24 , Setting ,

Oxalic .

Setting pH (T able 5.9)

. Setting 24 pH 3.373.39 , Setting 1 5

3.563.66 . Oxalic

, .

5 .7 .3

1 ,

, (Fig . 5.9.c)

, (Fig . 5.9. a , b)

. 2 1 (Fig . 5.10.c)

. 2 (Fig . 5.10 a,b) ,

.

5 .7 .4

T able 5.8 3 .

Setting 1 , 1

- 95 -

T able 5 .7 D e c ont am in ation m o del in re du c tion pro c e s s

at t hre e dif f e re nt c on dit ion s

(g / L )

1

Setting 1 Setting 2 Setting 4

Oxalic 0.403 0.747 0.713

Citric 1.654 0.919 1.489

LiOH 0.302 0.302 0.302

2


Oxalic 0.403 0.679 0.576

Citric 1.654 1.507 1.287

LiOH 0.302 0.302 0.302

3


Oxalic 0.403 0.403 0.403

Citric 1.654 1.654 1.654

LiOH 0.302 0.302 0.302

- 96 -

a . Condition

b . Condition

c. Condition

F ig . 5 .9 S E M an aly s i s at diff erent c on dit ion s in re du ct ion proc e s s -

- 97 -

a . Condition

b . Condition

c. Condition

F ig . 5 .10 S E M an aly s i s at diff erent c on dit ion s in re du ction pro c e s s -

- 98 -

Setting 2, 2 Setting 3, 3 Setting 1 ,

1 Setting 4, 2 Setting 5, 3 Setting 1

. 0.0012g 0.0031g

.

.

(0.0010g 0.0020g )

T able 5 .8 Com pari s on of w eig ht lo s s in re du ction pro c e s sat thre e diff erent c on dit ion s < T able 4 .1 >

(g ) 56.0130 55.9275 55.8068

(g ) 56.0118 55.9254 55.8050

(g ) 0.0012 0.0031 0.0018

5 .7 .5 pH (mV )

2 pH

T able 5.9, 10 . pH

pH . T able 5.9,

10 3

. Fig . 5.8 Setting 2,

3, 4 . T able 5.910 Setting 2, 3, 4

, 1 2 , 1 pH

. Fig . 5.8

Setting 5 T able 5.910 2 pH

. Fig . 5.8 Setting 5 Setting 24

Setting 1 T able 5.910 Setting 1 ( 1

2 , 1 )

- 99 -

T able 5 .9 Com pari s on of pH (m V ) in re du ct ion pro c e s s at thre e

diff eren t c on dit ion s -

1

pH(Setting 1)

3.56

(Setting 2)

3.38

(Setting 4)

3.39

(mV ) 242 255 256

2

pH(Setting 1)

3.55

(Setting 3)

3.37

(Setting 5)

3.66

(mV ) 242 255 235

3

pH(Setting 1)

3.50

(Setting 1)

3.49

(Setting 1)

3.52

(mV ) 245 246 243

- 100 -

T able 5 .10 Com pari s on of pH (m V ) in re du c tion pro c e s s at thre e

diff eren t c on dit ion s -

1

pH(Setting 1)

3.12

(Setting 2)

2.95

(Setting 4)

2.83

(mV ) 273 283 298

2

pH(Setting 1)

3.20

(Setting 3)

2.93

(Setting 5)

3.08

(mV ) 268 283 280

3

pH(Setting 1)

2.97

(Setting 1)

2.94

(Setting 1)

2.95

(mV ) 281 286 286

- 10 1 -

pH .

pH

.

- 102 -

6

6 . 1 (K K )

(1) SUS304L

, HNO3 .

HNO3 .

(2) HNO3

HNO3 6.5g/ L7.5g/ L.

(3) KMnO4 SUS304L .

(4) HNO3

, HNO3 HCl, H2 SO4 .

(5) HNO3 ,

SUS304L .

SUS304L .

HNO3

.

(6) 0.0030g0.0040g (100)

. 0.0020g

, 0.0050g

.

(7) pH pH : 1.5, pH : 1.8,

pH : 2.5 , pH

.

- 103 -

6 .2 (K K D )

(1) , 85

75 .

(2) 85, 3, 4

.

(3) Citric Acid Oxalic Acid

.

(4) 3 .

(5) 0.00120.0031g .

(6) pH ,

, , KMnO4

H + HNO3

.

- 104 -

Re feren c e

1. , T VCS (1995)

2. () ,

(1997)

3. (), ,

(1998)

4. EPRI, "Sourcebook for Chemical Decontamination of Nuclear Power Plants",

Special Report , Project 2296- 15 (1989)

5. EPRI, "A Review of Plant Decontamination Methods", Project 2296- 15, Final

Report (1989)

6. EPRI, "Corrosion T esting of LOMI Decontamination Reagent s", Project 2296- 4,

Final Report (1985)

7. ASM Specialty Handbook, Stainless Steels , pp. 134228 (1994)

8. D. L. Piron , "T he Electrochemistry of Corrosion", NACE, pp. 136 (1991)

9. D. A . Jones , "Principles and Prevention of Corrosion", Maxw ell Machillan

International Editions, pp . 1520 (1996)

10. , , , pp. 104119 (1995)

11. R. L. Jones , "Prevention of Stress Corrosion Cracking in Boiling Water

Reactor s", NACE, MP, Vol. 26, No. 2, pp. 7073 (1991)

12. ,

, pp. 917 (1999)

13. AST M, "Nuclear Power", Corrosion T est and Standard, No. 67, pp . 611- 620

(1995)

14. K. R. T retheway and J . Chemberlain , "Corrosion for Science and

Engineering", Longman, pp. 69129 (1995)

15. , , , pp. 3459 (1988)

16. AST M, "Standard Reference T est Method for Making Potentiostatic and

Potentiodynamic Anodic Polarization Measurements", Annual Book of AST M

Standards, G5, Vol. 03.02, pp. 6373 (1994)

17. R. E. Lee, Scanning Electron Microscopy and X-Ray microanalysis , pp. 116

(1993)

18. , , , pp . 17 (1994)

19. D. D. Ebbing , "General Chemistry ", , pp . 577581 (1993)

20. A . J . Sedriks , "Corrosion of Stainless Steels", T he Electrochemical Society ,

pp. 147166 (1996)

21. D. Behrens , "DECHMA Corrosion Handbook", Vol. 10. pp. 1291 (1991)

22. D. Behrens , "DECHMA Corrosion Handbook", Vol. 8. pp. 1244 (1991)

23. C. W . Kovach, "T ypes 304 and 316 Stainless Steels Can Experience

Permanganate Pitting in Water - handling Systems", NACE, MP, Vol. 30, No. 9,

pp. 7075 (1999)

24. R. A . Speranzini, P . A . Burchart , & K. A . Kanhai, "Corrosion Response of

Nuclear Reactor Materials to Mixtures of Decontamination Reagent s", NACE,

MP, Vol. 24, No, 3, pp. 67- 72 (1989)

25. ASM, "Metals Handbook", Corrosion , Vol. 13, pp . 231241, pp. 11491173

(1987)
Abstract1 1.1 1.2 1.3 2 2.1 2.2 2.3 2.4 2.4.1 (Pitting Corrosion)2.4.2 (Intergranular Corrosion)3 3.1 RCP 3.1.1 (KK)3.1.2 (KKD)3.2 3.2.1 3.2.2 3.2.3 3.3 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5 pH (mV)4 (KK) 4.1 4.2 4.2.1 4.2.2 4.2.3 4.2.4 2 4.2.5 4.3 4.3.1 1. 4.3.2 2. 4.3.3 3. 4.3.4 4(,). 4.3.5 5(,). 4.3.6 6(,,). (3, 5 ) 4.3.7 7. 4.3.8 8(,). 4.4 4.4.1 4.4.2 4.4.3 4.4.4 4.4.5 4.5 pH 4.6 4.6.1 4.6.2 4.6.3 pH() 5 (KKD) 5.1 5.2 5.2.1 (65 , 75 , 85 ) 5.2.2 (65 , 75 , 85 ) 5.3 5.3.1 5.3.2 5.4 5.4.1 5.4.2 5.4.3 5.4.4 5.4.5 5.5 pH (mV) 5.5.1 , , pH 5.6 5.6.1 Oxalic Acid Citric Acid 5.6.2 5.6.3 5.6.4 pH 5.7 5.7.1 5.7.2 5.7.3 5.7.4 5.7.5 pH (mV) 6 6.1 (KK)6.2 (KKD)

化學除染工程이 304L 스테인레스강의 耐蝕性에 미치는...

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