experimental studies on steel corrosion in lead-bismuth with … · 2005. 2. 4. · koji hata,...
TRANSCRIPT
-
INES-1#101 1
Experimental Studies on Steel Corrosionin Lead-Bismuth with Steam Injection
Koji Hata, Kazuyuki HaraNuclear Development Corporation
Minoru TakahashiResearch Laboratory for Nuclear Reactors
Tokyo Institute of Technology
-
2
Objectives
BackgroundFeasibility study of Pb-Bi direct contact boiling water reactor (PBWFR) for innovated nuclear reactor energy system.PurposeTo investigate the compatibility of high Cr steel
in the steam injecting Pb-Bi Study items
Effectiveness of Cr contents for corrosion resistance Influence of (PH2/PH2O) ratio in the injecting steam
on corrosion behaviorEffect of temperature on the steel corrosionSelection of more promising Cr steel and
evaluation of its applicability
-
3
System of the Experimental Apparatus
Pb-Bi Test Sub-systemSteam Supply Sub-system
Pb-Bi drain tank
Pb-Bitest tank
vacuum pump
exhaust gasheader
cooling water
DH meter
gas bubbling
flow meter
pump
filter
pump
waterconditioning
tank
condenser
steamgenerator
Ar gas
H2 gas
level sensorview port
oxygen sensor
chimney
slug filter
injection nozzle
-
4
Chimney
Test Specimens
Pb-BiCirculation
Pb-Bi Test Tank
Steam Bubbles
Steam Injection Steam Exhaust
Corrosion Test Concept
-
5
Chemical Composition of Tested Materials (wt.%)
C Si Mn Ni Cr Mo W V Nb0.1 0.1 0.2 0.02 7.7 ~ 1.9 0.2 ~0.1 0.4 0.4 0.1 8.6 1.0 ~ 0.2 0.080.1 0.3 0.5 0.3 8.8 0.3 1.9 0.2 0.07
0.15 0.1 0.5 0.6 10.0 0.5 ~ 0.2 ~0.1 0.3 0.5 0.2 12.0 1.1 1.0 0.3 0.10.1 0.3 0.5 0.3 12.0 0.3 1.9 0.2 0.05
0.01 1.0 0.5 4.5 16.0 ~ ~ ~ 0.20.01 1.4 0.7 ~ 17.7 ~ ~ ~ ~
F82HSTBA28
RECLOY17-5PH
Steel
NF616TMK1
HCM12HCM12A
-
6
Summary of the Experimental Parameters
400 450 500O ~ ~O O O
O ~ ~O ~ ~
O : tested, ~ : not tested
ExposurePeriods
Oxygen Potential Relatives
0.25 MPa 500 hours
Temperatures (℃)
5 x 10-6
1 x 10-5
DH
500 ppb1,000 ppb
1 x 10-6
Pressuresin Test TankP H2/P H20
< 3 x 10-7 < 30 ppb100 ppb
P H2P H2O
M H2O= (DH ) M H2 M H2O = molecular weight of H2O
M H2 = molecular weight of H2
(DH )=disolved hydrogen concentrationrelashionship between (P H2/P H2O) and DH
-
7
Oxygen Potential: Ox Electro-motive Force: Eand Oxygen Concentration: C
Nernst’s equation for electro-motive force
E = ( OREF – OPb-Bi )/nFwhere E: electro-motive force for an electrochemical system
OREF : oxygen potential of reference electrode OPb-Bi : oxygen potential of Pb-Bi
n: atomic valence of oxygen ion, F: Faraday’s constant
Calculation of E for oxygen concentration of C
E = [OREF - △GPb(Bi)-oxide - RTln(C/C0)] / nFwhere E: electro-motive force calculated for oxygen concentration of C
△GPb(Bi)-oxide : Gibb’s free energy of formation for Pb(Bi)-oxideR: gas constant, T: temperatureC : oxygen concentration in Pb-Bi, C0 : oxygen solubility in Pb-Bi
-
8
Experimental Conditions for E, C, and T
0
100
200
300
400
500
600
250 300 350 400 450 500 550 600
Temperature (℃)
E(m
V)
Fe3O4 formation
(Pb-Bi) oxide formation
oxygen in Pb-Bi(wt.fraction)
1.0E-10
1.0E-11
1.0E-9
1.0E-8
1.0E-7
1.0E-6
Experimental Condition
-
9
Fe in steel
before exposure (Wa )
Fe in steel
O in Pb-Bi
exposure in Pb-Bi
Pb-Bi
Fe
(FeCr)3O4Fe3O4Pb-Bi
Fe
(FeCr)3O4Fe3O4Pb-Bi
after exposure
after exposure
Fe
(FeCr)3O4
Fe3O4into Na
Pb-Bi
Na treatment (Wb)Fe
(FeCr)3O4into
citrate sol.
citrate sol. Treatment (Wc)
Process Flow for the Post-Exposure Treatment
-
10
Surface of HCM12A by Post-Exposure Treatment
optical microscope
4 mm4 mm 4 mm
before exposure test Na-ethanol treatment citrate teatment
before exposure test Na-ethanol treatment citrate teatment
1,000μm1,000μm 1,000μm
electron microscope
-
11
Fe
(FeCr)3O4into
citrate sol.
Fe
(FeCr)3O4
Fe3O4into Na
Pb-Bi
Fe in steel
before exposure (Wa ) citrate sol. Treatment (Wc )Na treatment (Wb )
Fe3O4: defective(porous) structure
(( (FeCr)3O4: sound structure
Weight Changes after Na treatment : (Wb – Wa) after citrate treatment : (Wc – Wa)
-
12
Weight Changes after Na Treatment (400℃)
-15.0
-10.0
-5.0
0.0
5.0
10.0
F82H
STBA28
NF616
TMK1
HCM12
HCM12A
17-4PH
RECLOY
Symbol of Steel (in the order of Cr content)
Wb-Wa
(mg/
test
pie
ce)
DH < 30 (ppb)
DH = 100 (ppb)
DH = 1,000 (ppb)
-
13
0
50
100
150
200
250
F82H
STBA28
NF616
TMK1
HCM12
HCM12A
17-4PH
RECLOY
Symbol of Steel (in the order of Cr content)
Wa-
Wc
(mg/
test
pie
ce)
DH = < 30 (ppb)
DH = 100
DH = 1,000
Weight Losses after Citrate Treatment (400℃)
-
14
0
40
80
120
160
200
F82H
STBA28
NF616
TMK1
HCM12
HCM12A
17-4PH
RECLOY
Symbol of Steel (in the order of Cr content)
Wa-
Wc
(mg/
test
piec
e)400℃
450℃
500℃
Weight Losses after Citrate Treatment (DH=100 ppb)
-
15
Conclusions & Future Works
Corrosion behaviors for some types of high Cr steel were examined.It was identified that :
Higher Cr content lead more corrosion resistance to Cr steel, and more than 9 % Cr content would be feasible for an application.
DH seemed to be little effective to control corrosion, but would be effective to avoid PbBi-slug formation or its precipitation.
DH should be limited less than 1,000 ppb to lower the amountof corrosion product (Fe-oxide ) released in Pb-Bi.
Corrosion rate increased with temperature, and Cr content effectiveness decreased at temperatures 500oC.
Corrosion rate of 12Cr steel were estimated as a few μm /y at 400oCand evaluated to be promising for a large reactor structure.
Further experiments are in progress to investigate the corrosion behavior of12Cr steel and other advanced materials (refractory metals and ceramics).