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A novel wiregauze supported Pt-Ru bimetallic nanoparticles
catalyst for the application of hydrogen mitigation under LOCA
condition
Salil Varma1, Kiran K. Sanap1,2, Suresh B. Waghmode2 and Shyamala R. Bharadwaj1
1Bhabha Atomic Research Centre - Mumbai2University of Pune - Pune
ICAER -2013, IITB, 10th December 2013 1/23
Nuclear energy - one of the non-renewable but clean sources of energy.
Nuclear power - a source of sustainable energy which reduces carbon emissions.
Nuclear power plants provide about 13% of worlds electricity.
Introduction
Nuclear Energy
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As concern with any
organization, its
safety is one of the
most prominent
questions.
Accidents at
Fukushima (Japan)
and Three Mile
Island (USA) nuclear
power plants
brought hydrogen
related issues into
the forefront.
Safety - one of the key aspect.
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1. Fuel bundle2. Calandria (reactor core)3. Adjuster rods4. Heavy water pressure reservoir5. Steam generator6. Light water pump7. Heavy water pump8. Fueling machines9. Heavy water moderator10. Pressure tube11. Pressure tube12. Cold water returning from
turbine13. Containment building made of
reinforced concrete
Inside of Nuclear Reactor
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Residual Heat Removal after reactor Shutdown
Radioactive Fission Products generate heat in form of Decay Products, a and b particles and g-rays.
Heat generated and g-ray lead to generation of hydrogen in the containment
Inside of Nuclear Reactor
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HYDROGEN IN NUCLEAR REACTORS
Design Basis AccidentRadiolytic generation (0.001 – 0.05 Kg/s)
Severe Accident
(LOCA + Failure of ECCS)Zirconium steam reaction (0.1 – 5.0 Kg/s)
Uranium steam reaction
Molten core concrete interaction
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METAL STEAM REACTION
Zr (s) + 2 H2O (g) → ZrO2 (s) + 2 H2 (g)
ΔH = -147.2 Kcal/g.mole
• 10 times higher kinetics compared to Radiolytic decomposition of water.
• 95 % hydrogen within 10 minutes.
• Oxidation of 30 % fuel sheath.
• Oxidation of 20 % Zirconium.
• 23500 gm moles of hydrogen in half an hour
Source: KAPP Safety report II
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10 100 1000 10000 100000 1000000
0.0
5.0k
10.0k
15.0k
20.0k
25.0k
30.0k
35.0k
40.0k
45.0k
50.0k
55.0k
60.0k
65.0k
Hyd
rog
en
Ge
ne
ratio
n (
gm
-mo
les)
Time (sec)
Cumulative time dependent hydrogen generation from metal-water reaction and radiolytic decomposition of water
Source: KAPP Safety report II
Cumulative
Metal-steam reaction
Radiolytic decomposition of coolant
Radiolytic decomposition of moderator
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THREATS POSED BY HYDROGEN
K. Fischer et. al., Nuclear Engineering and Design, 209 (2001) 147.
Hydrogen conc. in air
Possible reaction
0% - 4% noncombustible
4% - 13% Combustible
13% - 59% Combustible, possibly detonable
59%- 75% Combustible
75% - 100% noncombustible
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Hydrogen Mitigation systems Deliberate ignition system
Pre and post inerting Dilute Venting
Passive Autocatalytic recombiner (PAR)
Advantages of PAR Auto initiation.
Not depend on external power supply.
Can be placed at any location in containment.
No pressure build up.
Free access to all containment area, No life support required for working
staff during regular operation/maintenance of plant.
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Pt+Pd/SS efficient catalysts for PAR; limited to 50 ppm of CO
New breed of catalysts which initiate room temperature H2-O2
recombination in presence of all feasible contaminants
Optimisation of electroless deposition method in terms of
precursor and reducing agent concentration, the rate of
noble metal deposition and its loading
To study the influence of different poisons like CO2, CH4, CO
and moisture on catalytic activity
Objectives of the present study
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S.
NoCatalysts Dil. HCHOa
Noble Metal
Precursor (ml)HCHO:NMb
Time of
Coating (h)Wt gain (%)
01 Pt 90 H2PtCl6 = 32 76 20 0.85
02 PtR1 90H2PtCl6 = 32
RuCl3 = 561 7 0.9
03 PtR2 90H2PtCl6 = 32
RuCl3 = 561 8 1.1
04 PtR3 90H2PtCl6 = 32
RuCl3 = 561 8 1.4
05 PtR4 90H2PtCl6 = 32
RuCl3 = 561 8 1.6
06 PtPd 120H2PtCl6 = 32
PdCl2 = 771 7 0.83
07 PPR 120
H2PtCl6 = 32
PdCl2 = 2.5
RuCl3 = 2.579 8 0.85
a = 1:10 diluted formaldehyde b = Noble Metal
Experimental
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Absorbance verses wavelength for Pt-Ru solution with time.
Absorbance at λmax = 260 nm for PtR1 and Pt catalysts bath solution
Coating kinetics of plating bath
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XRD
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~7.0 nm Crystallite Size
~24.0 nm Crystallite Size
a b
c d
e f
SEM images of
(a) Bare wiregauze
(b) Etched
Wiregauze (c)
PtR1at 2.5K,
(d) PtR4 at 2.5K,
(e) PtR1 at 10K
and
(f) PtR4 at 10K.
Surface morphology - SEM
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TEM
TEM image and particle size distribution of PtR1 catalyst respectively. Particle size is varied from 0-20 nm mostly.But average particles size is in the range of 0-10 nm. ICAER -2013, IITB, 10th December 2013 16/23
D. Pressure gauge
A
D
GF
H
E
C
B
A. Fixed volume injector (0.25 l)
B. Air pump
circulating
C. SS reactor (40 l)
E. & F. mV meterG. Hydrogen monitor
H. Thermocouple
S. Catalytic sample
S
Block diagram representing the experimental setup for catalytic activity evaluation.
Catalytic activity
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Catalytic activity for various Pt-Ru samples and their temperature rise for recombination of 4 % hydrogen in air.
H2 Concentration and temperature as a function of time for H2-O 2 reaction in presence of PtR1catalystICAER -2013, IITB, 10th December 2013 18/23
Catalytic activity of PtR1 catalyst in presence of CH4, CO2, relative humidity and after flushing
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For Pt, PtPd, PPR and PtR1 catalysts
Catalytic activity in presence of Carbon monoxide
Catalytic activity of PtR1 catalyst in
presence Carbon Monoxide
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Reproducibility of Catalytic Activity of PtR1 catalyst
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Conclusions
Pt-Ru bimetallic catalyst prepared by electroless deposition
method on Stainless Steel support.
Catalyst with noble metal loading of 0.9 % found to be
optimum.
Catalyst found to be active for room temperature initiated
catalytic recombination of H2 and O2 in air.
Catalytic activity of this catalyst remain unaffected in
presence of CH4, CO2 and relative humidity.
Catalyst is found to exhibit enhanced catalytic activity in
presence of 400 ppm of carbon monoxide.
The platinum-ruthenium catalyst with 0.9 wt% noble metal
loading on stainless steel wire gauze is found to comply
with various requirements for application in PAR.ICAER -2013, IITB, 10th December 2013 22/23
Thank Youfor your
kind attention