1. A Seminar Presentation on
NUCLEAR
MICROBATTERY
A Portable Energy Source
1

2. INTRODUCTION
• Need for compact reliable light weight and
self-contained power supplies.
• Chemical batteries require frequent
replacements and are bulky.
• Nuclear reactors offer economical and
technical problems.
• Fuel and Solar cells are expensive and requires
sunlight respectively.

3. • Nuclear batteries have lifespan upto decades
and nearly 200 times more efficient.
• Do not rely on nuclear reaction , so no
radioactive wastes.
• Uses emissions from radioactive isotope to
generate electricity.
• Can be used in inaccessible and extreme
conditions.

4. HISTORICAL DEVELOPMENTS
• Idea was introduced in 1950 and patented to
Tracer Lab.
• Radioisotope electric power system developed
by Paul Brown.
• He organized an approach to harness energy
from the magnetic field of alpha and beta
particles using Radium-226.
• Low efficiency due to loss of electrons.

5. ENERGY PRODUCTION MECHANISMS
Betavoltaics :
• Alternative energy technology.
• Provides extended battery life and power
density.
• Uses energy from beta particles.
• Beta particles from radioactive gas captured in
Si wafer coated with diode material.
• Absorbed radiation creates electron-hole pair.
• Results in the generation of electric current.

6. Representation of basic beta voltaic conversion

7. The Energy Conversion Mechanism
• Before the radioactive source is introduced , no
current flows as the electrical forces are in
equilibrium.
• As a beta emitter is introduced , electrons are
knocked out by its energy.
• Generates electron-hole pairs in the junction.
• When beta particle imparts more than ionization
potential the electron rises to a higher level.

8. • Fermi voltage established between the electrodes.
• Potential difference drives electrons from electrode A
through the load where they give up the energy.
• Electron is then driven into electrode B to recombine
with a junction ion.
• Betavoltaics does not have solar-cell efficiency.
• Electrons shoot out in all directions; hence lost.
• Porous Si diodes with pits provide a 3-D surface
thereby increasing the efficiency.

9. Direct charging generators:
• Primary generator consists of LC tank circuit.
• Energy from radioactive decay products sustain
and amplify oscillations.
• Circuit impedance has coil wound on a core
composed of radioactive elements.
• Decay by alpha emission; hence greater flux of
radioactive decay.

10. Schematic Diagram of an LC resonant circuit
3 – capacitor
5 – inductor
9 – transformer T primary winding
11 – resistance
7 – core with radioactive elements

11. Working
• Oscillations induced in LCR circuit damp out due to
loss of energy.
• Here energy is imparted to the alpha particles
during the decay of elements in the core.
• This energy is introduced to circuit when alpha
particles are absorbed by the inductor.
• Oscillations sustain until amount of energy
absorbed=amount of energy dissipated in ohmic
resistance.
• This excess energy is delivered to the load
connected across transformer T secondary
winding.

12. FUEL CONSIDERATIONS
• Avoiding gamma rays in decay chain.
Ra-226 produces Bi-214.
Strong gamma radiation.
Shielding makes it bulky.
• Half life.
• Particle range.
• Cost.

13. ADVANTAGES
• Life span- minimum of 10 years.
• Reliable electricity.
• Amount of energy highest.
• Lighter with high energy density.
• Efficient; less waste generation.
• Reduces green house and associated effects.
• Fuel used is the nuclear waste from nuclear
fission.

14. APPLICATIONS
• Space applications:
Unaffected by long period of darkness and
radiation belts like Van-Allen belt.
Compact and lighter in weight.
Can avoid heating equipments required for
storage batteries.
High power for long time independent of
atmospheric conditions.
NASA is trying to harness this technology in space
applications.

15. • Medical applications:
In Cardiac pacemakers
Batteries should have reliability and longevity to
avoid frequent replacements.
• Mobile devices:
Nuclear powered laptop battery Xcell-N has
7000-8000 times more life.
No need for charging, battery replacing.

16. • Automobiles:
In initial stages.
No running short of fuel.
Possibility of replacing ionic fuels with its advantages.
• Under-water sea probes and sea sensors:
In sensors working for long time.
At inaccessible and extreme conditions.
Use in coal mines and polar sensor applications too.
• For powering MEMS devices : in optical switches and
smart dust sensors.

17. DRAWBACKS
• High initial cost of production as its in the
experimental stage
• Energy conversion methodologies are not
much advanced.
• Regional and country-specific laws regarding
use and disposal of radioactive fuels.
• To gain social acceptance.

18. CONCLUSION
• Small compact devices of future require small
batteries.
• Nuclear batteries increase functionality,
reliability and longevity.
• Until final disposal all Radiation Protection
Standards must be met.
• Batteries of the near future.

19. THANK YOU