Water chemistry for SCWR
M.Zychová, J. Berka, K. Vonková, R. Fukač
Research Centre Řež Ltd.
[email protected]
GIV International forum (GIF)
• The Generation IV International forum (GIF)
– organization to carry out the research & development of the new generation of
nuclear reactors
– GIF determined the goals
• sustainability, economics, safety and reliability
• the six reactor concepts chose
•very high temperature reactor,
•sodium-cooled fast reactor,
•gas-cooled fast reactor,
•lead-cooled fast reactor,
•molten salt reactor ,
•supercritical water-cooled reactor (SCWR).
2
Supercritical Water
–
–
–
–
Above 374 C, 22,05 MPa
(typically 600 C, 25 MPa)
Interesting medium
Problem with proper constructional material
Nature supercritical water
„black smokers“
•
•
•
•
•
Sub- and SCW extraction
SCW oxidation
SCW gassification
SCW as reaction medium
SCW as coolant
–
–
Fossil fueled SCW-cooled power plant
Nuclear SCW-cooled power plants
Use of SCW in power engineering
 Fossil fueled SCW-cooled power plant
– Ledvice 6 Power plant – under construction
4
4
Environment
Tc
SCWO
SCWR
Water-cooled
NPPs
Fossil-fueled plants
Temperature
Water chemistry
•Proper water regime enables:
–
–
–
–
Reduced corrosion product transport and release
Reduced flow accelerated corrosion of the feedwater system piping
Reduce maintance costs
Minimizing corrosion, fouling, activity and corrosion product transport and
deposition
– Optimizing thermal performance
– Maximize component lifetime
Fossil-fueled supercritical water-cooled power plants
Water chemistry
Ammonia + hydrazine
Hydrazine only
Chelate + NH3 + N2H4
pH 7 with oxygen
Combined mode
pH at 25 C
Details
-
0.7 - 1 mg amine/kg
9.1 - 9.4
NH3 + N2H4
8.5 - 9.5
NH3
9.1 - 9.6
-
9.1
NH3<0.8mg/kg to avoid copper transport
>9
NH3 or cyclohexylamine + hydrazine
8 - 8.5
N2H4 at 60 - 100 μg/kg
7.7
N2H4 at 60 - 100 μg/kg
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80μg/kg chelate, 0.8 mg/kg ammonia, 0.2 mg/kg hydrazine
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Increases thermal conductivity of iron oxide deposits
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50 - 200 μg O2/kg, conductivity <0.1 μS/cm
6.5 - 7.3
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Reaction of Fe(OH)2+O2 slow compared to reaction with H2O2
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<0.15 μS/cm, 0.2 - 0.4 mg O2/kg at boilet inlet
8 - 8.5
NH3 + O2 ↔NH3 provides slight buffering of pH so that impurities do not cause wide swings in the pH,
especially to the acid side where corrosion rates can increase
Water chemistry
Selected water regimes are (BWR):
NWC – normal water chemistry - pure water, 125 ppb of oxygen
HWC – hydrogen water chemistry – 3-6 Nml/kg H2O H2
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Main problem:
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–
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great difference between the input temperature and the output temperature in the active zone in critical
temperature area
To establish optimal operating conditions (various solubility of gases,…)
Corrosion product release and transport
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–
Water regime – suppress the contamination of turbine
Similar to BWR – single-circuit, NO RECIRCULATION LOOPS TO PROVIDE THE PURIFICATION AND
TREATMENT OF MEDIUM
Corrosion product transport
Turbine
t
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Processes controlling
mass (particle)
transport:
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–
–
–
–
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Diffusion
Thermophoresis
Turbulence
Gravity
Electrical forces
Van der Waals forces
Core
Condenser
Solubility(mol/kg)
Solubility(mol/kg)
Corrosion product solubility
Temperature ( C)
Temperature (oC), Density (kg/m3)
800
Cladding Surface
Temperature
Deposited Iron
Loading*
0.06
700
0.05
600
0.04
500
400
0.03
Bulk Coolant
Temperature
300
Bulk
Coolant
Density
200
0.02
Cladding
Corrosion
0.01
100
0
0
0
1
2
3
Distance along Fuel Channel (m)
Inlet iron concentration =10-8 kg/m3
4
5
Iron Loading (kg/m2/a), Corrosion Rate/10 (mdd)
Conditions in the core
Řež facilities
• Nuclear Research Institute Group (NRI)
• Research Centre Rez (CVR)
– part of NRI group, large facilities operation
• JHR Hot Cells group
• Research reactors (0 power and LVR-15), GIV experimental loops
• International programs – 7FP, EERA, SUSEN
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New experimental hall
• Large experimental hall for pre
irradiation testing of equipment
• Loops construction
• Testing operation
• Fusion
– BESTH (ITER PFW qualification)
• GIV – pre in-pile
– PbLi
– SCWL loop
– He loop
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SCWL
Facility for material and water chemistry testing –
Supercritical water loop (SCWL)
Pressure
25 MPa
(max. 32 MPa)
Temperature
max in AC 600 oC
max in loop 390 oC
Flow (Active channel)
200 - 500 kg·h-1
Flow (loop)
200 - 500 kg·h-1
Volume
42 dm3
Flow (filtration circuit)
30 kg·h-1
Sampling rate
0.2 kg·h-1
Flow (measurement system)
2 x 12 kg·h-1 ( HP, LP)
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Irradiation channel (SCWL)
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HTHL
Thank you for your attention.
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References
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USA.
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P.Kritzer, J. of Supercritical Fluids 29 (2004) p. 1 – 29.
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W.G. Cook and R.P. Olive Prediction of Crud Deposition in a CANDU-SCWR Core Through Corrosion Product Solubility
and Transport Modelling,, 5th Int. Sym. SCWR, Vancouver, BC, Canada, March 13-16, 2011
D. Guzonas, IAPWS Annual meeting 2011, 5-9 September 2011, Pilsen, Czech Republic