2010 ISOE Asia ALARA Symposium
Development of Hi-F Coat
for Carbon Steel Piping
Hitachi-ＧＥ Nuclear Energy, Ltd.
H. Matsubara, N. Usui, M. Nagase
Energy & Environmental Research Laboratory,
Hitachi, Ltd.
T. Ito, H. Hosokawa
© Hitachi-GE
Nuclear Energy, Ltd. 2010. All rights reserved.
コピーライトの表示については、作成元で責任を持って適宜変更してください。
⇒
１．Application result of Hi-F Coat for SS
Low recontamination by Hi-F Coat was confirmed for Stainless Steel.
Dose rate of PLR inlet piping（mSv/h)
5
NWC
HWC
4
PLR（A)
Point 1
Point 2
PLR（B)
NWC preoxidation operation
3
Pipe
replacement
Chemical decon.
Hi-F Coat
NWC preoxidation
(90 days）
Shroud replacement
Chemical decon.
2
1
0
17
18
19
20
Hi-F Coat ; Hitachi Ferrite Coating
NWC ; Normal water chemistry
HWC ; Hydrogen water chemistry
21
22
23
24
25
Number of outage（-）
26
27
28
M. Nagase, et al.,2009 ISOE Asian ALARA Symposium
© Hitachi-GE Nuclear Energy, Ltd. 2010. All rights reserved.
1
2．Enlargement of Hi-F Coat application area
CUW piping is one of the biggest sources of radiation exposure.
【Countermeasure to reduce recontamination】
60Co
Recontamination
No treatment
in oxide
film
Operation
Decon.
Reduction
Hi-F Coat
Principal: Reduction of 60Co deposition by reducing base metal corrosion
【System and its countermeasure】
System
RRS※1
RWCU※2
Material
SS※3
SS
CS※4
Problem
・RI deposition
・RI deposition
・Corrosion
Countermeasure
Ｈｉ-Ｆ
No method after
chemical decon.
※1 ; Reactor recirculation system
※2 ; Reactor water clean up
※3 ; Stainless steel ※4 ; Carbon steel
© Hitachi-GE Nuclear Energy, Ltd. 2010. All rights reserved.
2
3．Problem of Hi-F Coat for CS
Hi-F Coat procedure for SS is not applicable for CS.
【Procedure of Hi-F Coat】
Heat-up
C2H2O4
N2H4
Reduction, clean-up
Repeat
Fe（HCOO）2
H 2O 2
Hi-F Coat treatment
N2H4
Decomposition
Final clean-up
Hi-F Coat method
Decomposition,
clean-up
400
Film amount （μｇ/cm2）
Oxidation
ＨＯＰ method
KMnO4
【Problem of film formation】
SUS
SUS
CS
200
-200
Base metal
corrosion
CS
© Hitachi-GE Nuclear Energy, Ltd. 2010. All rights reserved.
3
4．Idea for Hi-F Coat procedure for CS
Higher pH is a key parameter to reduce CS corrosion.
【Procedure of film formation for SS】
【Idea for film formation】
Solution pH (-)
Pure water
7
H2O2 & N2H4
Fe(HCOO)2
6
Film
formation
5
4
Apply to CS
・Surface corrosion
BM ・No film
Time
CS corrosion rate（g/m2/h）
0.4
0.3
Countermeasure
・Low corrosion
BM
at higher pH
0.2
0.1
0
3
4
5
6
Solution pH (-)
7
8
BM ; Base Metal
© Hitachi-GE Nuclear Energy, Ltd. 2010. All rights reserved.
4
5．Conditions of film formation
【Experimental apparatus】
TP
90℃
pH
Pure water１ℓ
N2bubbling
Heat up（90℃）
Test piece
Chemicals
Reaction Start
3 hours
Film formation
Analysis
Analysis method
・Crystal structure・・・・X ray deflection
・Binding status・・・・XPS
・Film structure・・・・SEM
・Film composition・・・・Raman spectrum
・・・・Auger spectrum
Chemical conc. (ppm)
1
2
3
N2H4
Ｆｅ(HCOO)2
H2O2
Former
(15)
(300)
(600)
New
method Mixing all chemicals in advance
8
Mixed chemicals
Fｅ(HCOO)2
pH （-）
N2 gas
【Injection order and pH】
7
New method
6
5
Ni金属皮膜形成
Former
4
N2 H4 , H2 O 2
© Hitachi-GE Nuclear Energy, Ltd. 2010. All rights reserved.
5
6．Film amount
The new method enables to make a enough film amount on CS.
Weight change （μｇ/cm2）
300
200
Ｈｉ-Ｆ Coat film
Target film amount
(90μg/cm2)
CS
2μm
100
0
-100
-200
-300
Former
New method
© Hitachi-GE Nuclear Energy, Ltd. 2010. All rights reserved.
6
7．Detail analysis of formed film
Fine mono layer of polycrystalline Fe3O4 was identified.
Protect film for work
Formed film
CS
2μm
Relative strength
【Crystal structure】 Polycrystalline Fe3O4
Fe3O4
BM
10 20 30 40 50 60 70 80 90100
Relative strength
【Film composition】 Identified as Fe3O4
Formed film
Fe3O4
Fe(OH)3
Fe2O3
200
600
800
400
-1
Raman shift (cm )
【Binding status】 Existing ratio agrees with Fe3O4
Relative strength
【Cross section】
700
Fe2+ Fe3+
710
720
730
© Hitachi-GE Nuclear Energy, Ltd. 2010. All rights reserved.
7
8．Co deposition test conditions
Test was performed under simulated NWC conditions.
Test conditions
（NWC）
Pressure Control Valve
Cooler
Demi.
Test
section
E. C.
DO
P
Hx.
P
Temperature
280 Ԩ
Time
500 h
Pressure
7.8 MPa
Concentration (ppb)
DO
100
DH
10
H2O2
200
Cr
5
Co-60
30
© Hitachi-GE Nuclear Energy, Ltd. 2010. All rights reserved.
8
9 Weight change
Weight gain of CS was reduced to about 1/4 under simulated NWC.
© Hitachi-GE Nuclear Energy, Ltd. 2010. All rights reserved.
9
10 Co-60 deposition
Co-60 deposition on CS was reduced to about 40%
under simulated NWC.
© Hitachi-GE Nuclear Energy, Ltd. 2010. All rights reserved.
10
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.
© Hitachi-GE Nuclear Energy, Ltd. 2010. All rights reserved.
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© Hitachi-GE Nuclear Energy, Ltd. 2010. All rights reserved.
12