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2010 ISOE Asia ALARA Symposium

Hitachi- ＧＥ Nuclear Energy, Ltd.

Development of Hi-F Coat for Carbon Steel Piping

H. Matsubara, N. Usui, M. Nagase

Energy & Environmental Research Laboratory, Hitachi, Ltd.

T. Ito, H. Hosokawa

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M. Nagase, et al.,2009 ISOE Asian ALARA Symposium

Low recontamination by Hi-F Coat was confirmed for Stainless Steel.

１． Application result of Hi-F Coat for SS

Hi-F Coat ; Hitachi Ferrite Coating

0

1

2

3

4

5

17 18 19 20 21 22 23 24 25 26 27 28Number of outage （ - ）

Dos

e ra

te o

f PLR

inle

t pip

ing

（m

Sv/h

)

PLR （ A)PLR （ B)

NWC HWC

Pipereplacement

NWC preoxidation operation

Shroud replacementChemical decon.

Chemical decon.Hi-F Coat

NWC preoxidation(90 days ）

Point 1Point 2

NWC ; Normal water chemistryHWC ; Hydrogen water chemistry

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CUW piping is one of the biggest sources of radiation exposure.

2 ． Enlargement of Hi-F Coat application area

System Material ProblemCountermeas

ure

RRS※1 SS※3 ・ RI deposition

Ｈｉ - Ｆ

RWCU※2SS

CS※4

・ RI deposition・ Corrosion

No method after chemical

decon.

【 System and its countermeasure 】

60Co in oxide film

No treatment

Hi-F Coat

Decon.

Recontamination

Operation Reductio

n

Principal: Reduction of 60Co deposition by reducing base metal corrosion

【 Countermeasure to reduce recontamination 】

※1 ; Reactor recirculation system※2 ; Reactor water clean up※3 ; Stainless steel 4 ; Carbon steel※

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Hi-F Coat procedure for SS is not applicable for CS.

3 ． Problem of Hi-F Coat for CS

Oxidation

Decomposition, clean-up

KMnO4

RepeatRepeat

C2H2O4

N2H4

Heat-up

Reduction, clean-up

Final clean-up

Hi-F Coat treatmentHi-F Coat treatment

Decomposition

Fe （ HCOO ） 2

H2O2

N2H4

【 Problem of film formation 】

-200

200

400SUS

CS

Base metal corrosion

SUS CS

Film

am

ou

nt

（μ

ｇ/c

m2

）

ＨＯ

Ｐ

met

ho

dH

i-F

Co

at m

eth

od

【 Procedure of Hi-F Coat 】

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Higher pH is a key parameter to reduce CS corrosion.

4 ． Idea for Hi-F Coat procedure for CS

Solution pH (-)

0

0.1

0.2

0.3

0.4

3 4 5 6 87

Solu

tion

pH

(-

)

7

4

6

5

Fe(HCOO)2

H2O2 & N2H4

Film formati

on

【 Procedure of film formation for SS 】

CS

corr

osi

on

rate

（g

/m2/h

）

Time

Apply to CS

・ Surface corrosion・ No film

Countermeasure・ Low corrosion at higher pH

【 Idea for film formation 】

Pure water

BM

BM

BM ; Base Metal

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5 ． Conditions of film formation

Pure water１ℓ N2bubbli

ngHeat up （ 90℃ ）

Reaction Start

Film formation

3 hours

Test pieceChemica

ls

Chemical conc. (ppm)1 2 3

FormerＦｅ

(HCOO)2

(300)

H2O2

(15)N2H4

(600)

New method

Mixing all chemicals in advance

AnalysisAnalysis method・ Crystal structure ・・・・ X ray

deflection・ Binding status ・・・・ XPS・ Film structure ・・・・ SEM・ Film composition ・・・・

Raman spectrum　　　　　　 ・・・・ Auger

spectrum

【 Experimental apparatus 】

Ni 金属皮膜形成

【 Injection order and pH 】

7

4

Mixed chemicals

F ｅ(HCOO)2

5

6

8

Former

New method

pH

（-）

N2 gas

pH

TP

90℃

N2H4, H2O2

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The new method enables to make a enough film amount on CS.

6 ． Film amount

300

200

100

0

-100

-200

-300

Former New method

2μmCS

Ｈｉ - Ｆ Coat film

Weig

ht

change （

μｇ

/cm

2）

Target film amount(90μg/cm2)

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Fine mono layer of polycrystalline Fe3O4 was identified.

7 ． Detail analysis of formed film

2μmCS

Formed film

Protect film for work

102030405060708090100

Fe3O4

BM

Polycrystalline Fe3O4

Raman shift (cm-1)200 400 600 800

Formed film

Fe(OH)3

Fe2O3

Fe3O4

Identified as Fe3O4

700 710 720 730

Fe2

+Fe3

+

Existing ratio agrees with Fe3O4

【 Cross section 】

【 Crystal structure 】

【 Film composition 】

【 Binding status 】

Rela

tive

stre

ngth

Rela

tive

stre

ngth

Rela

tive

stre

ngth

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Test was performed under simulated NWC conditions.

8 ． Co deposition test conditions

DO

Demi.

Cooler

E. C.

Hx.

Pressure Control Valve

Test section

Temperature 280 ℃

Time 500 h

Pressure 7.8 MPa

Concentration (ppb)

DO 100

DH 10

H2O2 200

Cr 5

Co-60 30

Test conditions （ NWC ）

P

P

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9 Weight change

Weight gain of CS was reduced to about 1/4 under simulated NWC.

0

20

40

60

80

100

120

140

160

Polished Hi- F

Wei

ght g

ain

(μ

g/cm

2 )

Simulated NWCDO：100 ppbDHP：200 ppbCr：5 ppbCo- 60：30ppbTime：500h

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10 Co-60 deposition

Co-60 deposition on CS was reduced to about 40% under simulated NWC.

0

0.2

0.4

0.6

0.8

1

1.2

Polished Hi- F

Dep

ositi

on a

mou

nt o

f Co

-60

(Rel

ativ

e)

Simulated NWCDO：100 ppbDHP：200 ppbCr：5 ppbCo- 60：30ppbTime：500h

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10 Summary

Film formation method on CS was studied in order to reduce corrosion and Co-60 deposition and its effect was confirmed.

【 Results 】

　　・ Film formation was realized by reducing CS corrosion.

　　・ Target film amount of 90 μg/cm2 was realized.

　　・ Weight gain was reduced to about 1/4 by Hi-F coat film under simulated NWC.

　　・ Deposition amount of Co-60 was reduced to about 40% by Hi-F coat film under simulated NWC.

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