1. 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 - Mumbai
2University of Pune - Pune
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2. Introduction
Nuclear Energy
 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.
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3. Safety - one of the key aspect.
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.
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4. Inside of Nuclear Reactor
1. Fuel bundle
2. Calandria (reactor core)
3. Adjuster rods
4. Heavy water pressure reservoir
5. Steam generator
6. Light water pump
7. Heavy water pump
8. Fueling machines
9. Heavy water moderator
10. Pressure tube
11. Pressure tube
12. Cold water returning from
turbine
13. Containment building made of
reinforced concrete
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5. Inside of Nuclear Reactor
Residual Heat Removal
after reactor Shutdown
Radioactive
Fission
Products generate heat in
form of Decay Products,
a and b particles and grays.
Heat generated and g-ray
lead to generation of
hydrogen
in
the
containment
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6. HYDROGEN IN NUCLEAR REACTORS
Design Basis Accident
Radiolytic 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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7. 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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8. 65.0k
60.0k
Hydrogen Generation (gm-moles)
55.0k
50.0k
45.0k
40.0k
Cumulative
35.0k
30.0k
Metal-steam reaction
25.0k
20.0k
15.0k
Radiolytic decomposition of moderator
10.0k
Radiolytic decomposition of coolant
5.0k
0.0
10
100
1000
10000
100000
1000000
Time (sec)
Cumulative time dependent hydrogen generation from metal-water
reaction and radiolytic decomposition of water
Source: KAPP Safety report II
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9. THREATS POSED BY HYDROGEN
Hydrogen
conc. in air
Possible reaction
0% - 4%
noncombustible
4% - 13%
Combustible
13% - 59%
Combustible,
possibly detonable
59%- 75%
Combustible
75% - 100% noncombustible
K. Fischer et. al., Nuclear Engineering and Design, 209 (2001) 147.
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10. 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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11. Objectives of the present study
 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
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12. Experimental
S.
Catalysts
Dil. HCHOa
Pt
90
02
PtR1
90
03
PtR2
90
04
PtR3
90
05
PtR4
90
06
PtPd
120
07
PPR
120
No
01
Noble Metal
Precursor (ml)
H2PtCl6 = 32
H2PtCl6 = 32
Time of
Wt gain (%)
RuCl3 = 5
H2PtCl6 = 32
RuCl3 = 5
H2PtCl6 = 32
RuCl3 = 5
H2PtCl6 = 32
PdCl2 = 7
H2PtCl6 = 32
76
Coating (h)
20
61
7
0.9
61
8
1.1
61
8
1.4
61
8
1.6
71
7
0.83
79
RuCl3 = 5
H2PtCl6 = 32
PdCl2 = 2.5
HCHO:NMb
8
0.85
0.85
RuCl3 = 2.5
a = 1:10 diluted formaldehyde
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b = Noble Metal
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13. Coating kinetics of plating bath
Absorbance verses wavelength for
Pt-Ru solution with time.
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Absorbance at λmax = 260 nm for
PtR1 and Pt catalysts bath solution
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14. XRD
~7.0 nm Crystallite Size
~24.0 nm Crystallite Size
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15. Surface morphology - SEM
a
b
SEM images of
(a) Bare wiregauze
c
d
(b) Etched Wiregauze
(c) PtR1at 2.5K,
(d) PtR4 at 2.5K,
(e) PtR1 at 10K and
e
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f
(f) PtR4 at 10K.
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16. 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.
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17. Catalytic activity
G. Hydrogen monitor
E. & F. mV meter
E
F
G
S. Catalytic sample
B. Air pump
circulating
H
D
B
A. Fixed volume
injector (0.25 l)
D. Pressure gauge
S
C
A
H. Thermocouple
C. SS reactor (40 l)
Block diagram representing the experimental setup for
catalytic activity evaluation.
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18. Catalytic activity for various Pt-Ru
samples and their temperature rise for
recombination of 4 % hydrogen in air.
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H2 Concentration and temperature as
a function of time for H2-O-2
reaction in presence of PtR1catalyst
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19. Catalytic activity of PtR1 catalyst in presence of
CH4, CO2, relative humidity and after flushing
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20. Catalytic activity in presence of Carbon monoxide
For Pt, PtPd, PPR and
PtR1 catalysts
Catalytic activity of PtR1
catalyst in presence
Carbon Monoxide
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21. Reproducibility of Catalytic Activity of
PtR1 catalyst
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22. 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.
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