153 salil varma

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


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.


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


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


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


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


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


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


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.


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


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


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


XRD


~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


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


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


For Pt, PtPd, PPR and PtR1 catalysts

Catalytic activity in presence of Carbon monoxide

Catalytic activity of PtR1 catalyst in

presence Carbon Monoxide


Reproducibility of Catalytic Activity of PtR1 catalyst


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

153 salil varma

Technology

hydrogen hydrogen

generation of hydrogen

catalytic activity icaer

hydrogen monitor

metalwater reaction

reinforced concrete

diluted formaldehyde

heavy water pump