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1All Rights Reserved. Copyright © 2008, Hitachi-GE Nuclear Energy, Ltd. 1-1※ この資料の複写、第 3 者への公開を固く禁じます。 All Rights Reserved. Copyright © 2009, Hitachi-GE Nuclear Energy, Ltd.
Application of Hi-F Coatfor Recontamination Reduction
at Shimane Unit 1Hitachi- GE Nuclear Energy, Ltd.M. Nagase, N. Usui, S. Oouchi
Energy & Environmental Research Laboratory, Hitachi, Ltd.H. Hosokawa
Chugoku Electric Power Company, Ltd.H. Kajitani, A. Yamashita, T. Minami
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Background
• Dose rate reduction effects don’t last long after operation.
• Recontamination reduction is needed to keep low dose rate.
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
out
let
pipe
Svh
)(m
Point 3Point 4
NWC HWC
Chemical decon.NWC preoxidation operation
Pipereplacemen
t
Shroud replacementChemical decon.
Abnormal crud deposition
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What is Hi-F Coat
Formation of fine outer magnetite film before power operation ⇒ Reduction of inner oxide film formation to pick up Co Hi-F Coat : Hitachi Ferrite Coating
Film of Hi-F Coat Oxide film in plants
Chemical form
Outer Fe3O4Fe3O4 、 Fe2O3 、Ni ( Co)Fe2O4
Inner - CoCr2O4 、 Cr2O3
Size of particle < 0.2μ m 1 ~ 10μ mThickness of film < 0.5μ m 3 ~ 10μ mTemperature 90℃ 280℃
Principal of recontamination reduction
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Section photograph of film
Formation of fine magnetite film ( thickness :~ 0.3μm )
Vapor deposited carbon
Base metal ( type 304 SS )
Film formed under NWC 200 h(DO: 300 ppb)
Film of Hi-F Caot
Outer (magnetite particle )Inner (chromite )
Coating layer (magnetite )
Vapor deposited carbon
Base metal ( type 304 SS )
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Reduction effect of activity deposition
( laboratory data)
・ Remarkable reduction of 60 Co deposition under HWC・ Continuous effect after 6 times of heat and cool ( Stable)
0
50
100
150
200
250
0 500 1000 1500 2000 2500 3000 3500
(h)浸漬時間
Co-
60(B
q/cm
2)付
着量
Hi-F Coat treatment
NWC treatment
Polished (no film)
~ 1/5
Am
ou
nt
of 6
0C
o d
ep
osi
tion
(B
q/c
m2)
Time (h)
DO:<10ppb, DH:50ppb, DH2O2:5ppb
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Outline of treatment procedure
Oxidation
Decomposition, clean-up
Final clean-up
KMnO4
Dissolution of chromium oxides
Fe2O3 , MFe2
O4
(M : Fe, Ni, Co)Cr2O3Base metal
RepeatRepeat
C2H2O4
N2H4
Dissolution of iron oxides
Heat-up
Reduction, clean-up
Hi-F Coat treatmentHi-F Coat treatment
Decomposition
Fe ( HCOO ) 2
H2O2
N2H4
Formation of fine ferrite (Fe3O4) film
HO
P
met
ho
dH
i-F
Co
at m
eth
od
Base metal
Base metal
Base metal
Base metal
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Outline of Hi-F Coat treatment equipments
Only a little equipments are needed to decontamination equipments.
Pump
CoolerIon exchange column
Catalyst column
Additional chemical injection system
Filter
Surge tank( with
heater )
Pump
Target( PLR piping etc. )
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Outline of Hi-F Coat treatment chemicals
Only iron formate is added to HOP method chemicals.
Chemical Conc. (ppm)
Remarks
HOP decon.process
KMnO4 200 ~ 300 For oxidation
(COOH)2 2000 For reduction
N2H4 ~ 600 For p H control
H2O2 - For decomposition of chemicals
Hi-F Coat treatmentprocess
Fe(HCOO)2
Fe :~ 250Formic ion :~
500
Raw material for film formationFormic acid is used for LOMI* process.
H2O2 - For ion value control
N2H4 200 ~ 500 For p H control* : LOMI is one of chemical decontamination method.
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Target of HOP decontamination & Hi-F Coat
PLR piping・ PLR pump inlet & outlet・ Ring header・ Riser piping(A & B loops)
HOP Hi-F Coat
1st time 1st time
1st &2nd time 2nd time
2nd time 2nd time
10
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Hi-F Coat treatment conditions
Parameter Planned value Measured value
Fe conc. 250±50 ppm 263 ~ 296 ppm
N2H4 conc. 200 ~ 600 ppm 160 ~ 560 ppm
11
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Hi-F Coat treatment results
P
P
Surge tank
Test piece unit
Temporary piping
12
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Hi-F Coat treatment results
More than target value of 0.1μm ( 60μg/cm2) was achieved.
Sample item Application Sample No.Deposited
amount ( μg/cm2)
Test piece
1st time1 2302 270
2nd time3 3024 192
3rd time5 1256 132
4th time7 4028 498
Temporary piping
2nd time A 1504th time B 359
13
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Surface observation (SEM)
Before Hi-F Coat(After decon.)
After Hi-F Coat
×1000
×10000
14
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Dose rate of PLR piping (1/2)
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 pi
ping
Svh
)(m
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
15
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Dose rate of PLR piping (2/2)
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
out
let
pipi
ngSvh
)(m
PLR A)(PLR B)(
NWC HWC
Chemical decon.NWC preoxidation operation
Pipereplacemen
t
Shroud replacementChemical decon.
Abnormal crud deposition
Chemical decon.Hi-F Coat
NWC preoxidation(90 days)
Point 3Point 4
16
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0
0.5
1
1.5
2
23 28
Dos
e ra
te o
f PLR
(m
Sv/
h)
After decon.After operationIncrease
No countermeasure
90 days NWCpreoxidation operation
Hi-F Coat+-54%
Effect of dose rate reduction (1/4)
Point 1: inlet piping
17
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0
0.5
1
1.5
2
23 28
Dos
e ra
te o
f PLR
(m
Sv/
h)
After decon.After operationIncrease
-81%
90 days NWCpreoxidation operation
Hi-F Coat+
No countermeasure
Effect of dose rate reduction (2/4)
Point 2: inlet piping
18
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0
0.5
1
1.5
2
23 26 28
Dos
e ra
te o
f PLR
(m
Sv/
h)
After decon.After operationIncrease
-60% 90 days NWCpreoxidation operation
Hi-F Coat+
54 days NWCpreoxidation operation
Contribution of Hi-F Coat-60%
No countermeasure
Effect of dose rate reduction (3/4)
Point 3: outlet piping
19
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0
0.5
1
1.5
2
23 26 28
Dos
e ra
te o
f PLR
(m
Sv/
h)
After decon.After operationIncrease
-74%
90 days NWCpreoxidation operation
Hi-F Coat+
No countermeasure
Contribution of NWC preoxidation-35%
Contribution of Hi-F Coat-39%
54 days NWCpreoxidation operation
Effect of dose rate reduction (4/4)
Point 4: outlet piping
20
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0
0.2
0.4
0.6
0.8
1
1.2
0 50 100 150
Time after start of chemical decontamination (h)
Rel
ativ
e do
se r
ate
(-) 27th outage
28th outage
1st cycle 2nd cycle
Effect on chemical decontamination
Hi-F Coat film was easy to be removed by chemical decontamination.
21
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Effect of Zn injection on Hi-F Coat
Farther Co deposition reduction can be expected with Zn injection.
Hitachi laboratory data
Time : 500hTemp. : 280℃ECP : -0.5V
0 2 4
Zn conc. (ppb)
0
20
40
60
80
100
PolishedHi-F Coat
60C
o d
ep
osi
tion
am
ou
nt
(Bq
/cm
2)
6
22
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Summary
1. Hi-F Coat was first applied to Shimane Unit 1 after
chemical decontamination.
2. Hi-F Coat treatment was successfully applied to the
decontaminated surface. Deposited amount of film
was about 270 μg/cm2 which was more than target
value of 60 μg/cm2.
3. Recontamination was suppressed about 1/2 to 1/3
after one operation cycle.
4. Coated film was easy to be removed by chemical
decontamination.
5. Farther dose rate reduction can be expected with Zn
injection.