The document summarizes a student's paper on nuclear micro-batteries. It discusses how nuclear micro-batteries provide a long-lasting, compact power source using radioactive decay. The mechanisms of betavoltaics and direct charging generators are described. Various isotopes are considered for use, and incorporation into MEMS devices and applications like medical implants, sensors, and mobile devices are discussed. Concerns around waste disposal are addressed. The conclusion is that nuclear micro-batteries show promise in applications requiring long-lasting power.

1. Nuclear micro-battery
By
VISHNU M T
SEM 7
ROLL NO: 90012068
Department of Instrumentation ,CUSAT

2. INTRODUCTION
 A burgeoning need exists today for small, compact, reliable, lightweight and self-
contained rugged power supply
 Its lifespan is decades and has 200 times more efficiency
 these power cells do not rely on a nuclear reaction or chemical process do not
produce radioactive waste products
 It is the answer for power supply to MEMS devices.
 Envisioned to be used in medical devices and remotely placed sensors.
 It will make its way to commonly used products like laptops and smart phones.
Surely its the batteries of near future.

3. Historical developments
 Idea came in beginning of 1950 at tracer lab
 Radio isotope electric power system developed by inventor Paul Brown was a scientific
breakthrough in nuclear power. . Brown’s first prototype power cell produced 100,000
times as much energy per gram of strontium -90(the energy source) than the most
powerful thermal battery yet in existence.
 The main drawback of Mr. Brown’s prototype was its low efficiency, and the reason for
that was when the radioactive material decays, many of the electrons lost from the
semiconductor material.
 With the enhancement of more regular pitting and introduction better fuels the nuclear
batteries are thought to be the next generation batteries and there is hardly any doubt
that these batteries will be available in stores within another decade.

4. Energy production mechanism
1) Betavoltaics
 Alternative energy technology that promises vastly extended battery life and power
density over current technologies.
 The functioning of a betavoltaics device is somewhat similar to a solar panel, which
converts photons (light) into electric current.
 Betavoltaic technique uses a silicon wafer to capture electrons emitted by a
radioactive gas, such as tritium.
 The junction between the two electrodes is comprised of a suitably ionisable medium
exposed to decay particles emitted from a radioactive source.
 Irradiated p-n junction produces electron hole pairs .
 It consist of 6 stages of energy transition of electrons .

5. A pictorial representation of a basic Betavoltaic conversion as shown in
figure 1. Electrode A (P-region) has a positive potential while electrode B (N-
region) is negative with the potential difference provided by me
conventional means.

6. The energy conversion mechanism for this arrangement involves energy flow
in different stages .
Stage 1:- Before the radioactive source is introduced, a difference in
potential between to electrodes is provided by a conventional means.

7.  Stage 2:- Next, we introduce the radioactive source, say a beta emitter, to
the system.
 Stage 3:- Further the beta particle imparts an amount of energy in excess of
ionization potential
 Stage 4:- next, the electric field present in the junction acts on the ions and
drives the electrons into electrode A and a Fermi voltage is established.
Naturally, the electrons in electrode A seek to give up their energy and go
back to their ground state (law of entropy).
 Stage 5:- the Fermi voltage derives electrons from the electrode A through
the load where they give up their energy in accordance with conventional
electrical theory.
Eb-energy of β particle
E1-ionization potential of junction
E2- stage 2 energy

10. 2) Direct charging generators
a)High Q LC tank circuit
 the primary generator consists of a high –Q LC tank circuit
 Core composed of radioactive nuclides connected in series with the primary winding of a
power transformer. . The core is fabricated from a mixture of three radioactive materials
which decay primarily by α emission and provides a greater flux of radioactive decay
products than the equivalent amount of single radioactive nuclei.
 Each α particles collide with more than one atoms and knocks out electrons imparting KE .
 Sustained oscillations are induced by absorption of radio active decay energy.
 Excess energy is transferred to load connected across transformer secondary

11. Schematic diagram of an LC resonant
circuit

12. WIRING DIAGRAM OF CONSTRUCTED NUCLEAR
BATTERY

13. b)Self-reciprocating cantilever
 Also a direct charging method
 A resonator is created by inducing movement due to attraction or repulsion resulting from
the collection of charged particles.
 Electrostatic force is driving force
 The radioactive source used was 63Ni with an activity of 1 mCi. The beam is 5 cm *5 mm,
made from 60 μm thick copper.
 A CCD camera connected to a VCR is used to record the movement of the beam and its
periodicity

15. A more analytical approach
α represents current emitted by
radioactive source
V is the voltage across source and beam
represent current leakage by air ionization
C is the capacitance of source and beam

16. We obtain the above equation

19. 3) optoelectrics
 Proposed by researchers of the kurchatov institute in Moscow.
 A beta emitter such as technetium-99 are strontium-90 is suspended in a gas or
liquid containing luminescent gas molecules of the exciter type, constituting “dust
plasma”.
 a comparably light weight low pressure, high efficiency battery can be realized.
 The surrounding weakly ionized plasma consists of gases or gas mixtures (e.g.
krypton, argon, xenon) with exciter lines, such that a considerable amount of the
energy of the beta electrons is converted into this light the surrounding walls
contain photovoltaic layers with wide forbidden zones.
 advantage of this design is that precision electrode assemblies are not needed
and most beta particles escape the finely-divided bulk material to contribute to
the batteries net power.
 disadvantage consists in the high price of the radionuclide and in the high
pressure of up to 10MPa (100bar) and more for the gas that requires an expensive
and heavy container.

20. Fuel considerations
The major criterions considered in the selection
of fuels are:
 Avoidance of gamma in the decay chain
 Half life
 Particle range
 Watch out for (alpha, n)reactions

22. Isotope selection
 A critical aspect of the creation of microbatteries for MEMS devices is the
choice of the isotope to be used as a power source.
 Isotope selection looks into : safety, reliability, cost, and activity.
 The half-life of the isotopes must be high enough so that the useful life of the
battery is sufficient for typical applications, and low enough to provide sufficient
activity.
 the new isotope resulting after decay should be stable, or it should decay
without emitting gamma radiation.
 The power dissipated for charging such an electromechanical capacitor would
be in the range of 10 to 100 nanowatts.

23. To explore the viability of the nuclear micro battery concept, some scoping calculations
need to be carried out. Using 210Po as an example, one can analyze the best case
scenario, assuming that the nuclear battery is created using pure 210Po. In this case, the
activity would be approximately 4,500 Ci per gram or 43,000 Ci per cubic centimeter. Thus,
for a characteristic source volume of 10-5 cubic centimeters (0.1 cm x 0.1cm x 10 microns),
one obtains approximately 0.5 Ci. Based on the results of previous experimental studies, the
available power would be on the order of 0.5 mW (about 1 mW/Ci). The power required for
MEMS devices can range from nanowatts to microwatts.

24. Incorporation of source into device
3 Methods
1) activation of layers within the MEMS device,
2) addition of liquid radioactive material into
fabricated devices
3) addition of solid radioactive material into
fabricated devices.

25.  Electroless plating is the plating of nickel without the use of electrodes but by
chemical reduction
 Metallic nickel is produced by the chemical reduction of nickel solutions with
hypophosphite using an autocatalytic bath.
 This type of nickel plating can be used on a large group of metals, such as steel,
iron, platinum, silver, nickel, gold, copper, cobalt, palladium and aluminum.
 The important factor influencing the plating process is the pH. The pH needs to be
maintained at 4.5-6 for plating to occur.
 Plating of nickel on gold was observed in about 15 minutes

26.  We have obtained glass microspheres (25 to 53 μm in diameter) that will emit low energy
3H beta radiation . These are obtained by irradiating 6Li glass silicate non-radioactive
microspheres in the UW Nuclear Reactor .
 Using this procedure, we can produce activities of up to 12.8 mCi per gram and per hour
of irradiation.
 This approaches will allow for higher power densities than the direct reactor activation
approach, but will provide less flexibility with respect to device design.
We are currently exploring the tradeoffs of the different options, and will shortly release
all the data needed to assess the viability of all of these approaches.

27. Waste disposal
Analysis proves that the environmental impact of disposing of these micro-devices once
their useful life has ended, as well as the associated costs are minimal. Since after three
half-lives the activity of the isotope has decayed to about 10% of the original activity, the
micro-batteries would be below background radiation level at the following times:

28. ADVANTAGES
 The most important feat of nuclear cells is the life span they offer, a minimum of
10years!
 As the energy associated with fissile material is several times higher than conventional
sources, the cells are comparatively much lighter and thus facilitates high energy
densities to be achieved.
 the efficiency of such cells is much higher simply because radioactive materials in little
waste generation .
 nuclear produced therein are substances that don’t occur naturally. example
strontium does not exist in nature but it is one of the several radioactive waste products
resulting from nuclear fission .
 . Thus substituting the future energy needs with nuclear cells and replacing the already
existing ones with these, the world can be seen transformed by reducing the green
house effects and associated risks.

29. DISADVANTAGES
 First and foremost, as is the case with most breathtaking technologies, the high initial
cost of production involved is a drawback but as the product goes operational and
gets into bulk production, the price is sure to drop .
 Size can sometimes be a problem . Eg : Xcell
 Complete efficiency is yet to be realized even though high efficiencies are realized in
laboratories
 A minor blow may come in the way of existing regional and country specific laws
regarding the use and disposal of radioactive materials

30. Applications
Nuclear batteries find many fold applications due to its long life time and
improved reliability. In the ensuing era, the replacing of conventional
chemical batteries will be of enormous advantages. This innovative
technology will surely bring break-through in the current technology which was
muddled up in the power limitations. MEMS devices, with their integrated
nuclear micro-battery will be used in large variety of applications, as sensors,
actuators, resonators, etc. It will be ensured that their use does not result in any
unsafe exposure to radiation

31. Space applications
 When the satellite orbits pass through radiation belts such as the van-Allen belts
around the Earth that could destroy the solar cells
 Operations on the Moon or Mars where long periods of darkness require heavy
batteries to supply power when solar cells would not have access to sunlight
 Space missions in the opaque atmospheres such as Jupiter, where solar cells would be
useless because of lack of light.
 At a distance far from the sun for long duration missions where fuel cells, batteries and
solar arrays would be too large and heavy.
 Heating the electronics and storage batteries in the deep cold of space at minus 245°
F is a necessity

32. Medical applications
 Used due to their increased longevity and better reliability.
 Can be used in for medical devices like pacemakers, implanted deep
fibrillations or other implanted devices that would otherwise require surgery
to replace or repair the best out of the box is use in ‘cardiac pacemakers .
 The definitions for some of the important parts of the battery and its
performances are parameters like voltage, duty cycle, temperature, shelf
life, service life, safety and reliability, internal resistance, specific energy
(watt-hour/ kg), specific power (watts/kg), and in all that means nuclear
batteries stands out. Compared to conventional batteries.

33. Mobile devices
 Xcell-N is a nuclear powered laptop battery that can provide between seven and
eight thousand times the life of a normal laptop battery-that is more than five year’s
worth of continuous power .
 Nuclear batteries are about forgetting things around the usual charging, battery
replacing and such bottlenecks
 a nuclear battery can endure at least up to five years. The Xcell-N is in continuous
working for the last eight months and has not been turned off and has never been
plugged into electrical power since .
 are going to replace the conventional batteries and adaptors, so the future will be of
exciting innovative new approach to powering portable devices.

34. Automobiles
 Although it is on the initial stages of development, it is highly promised that the nuclear
batteries will find a sure niche in the automobiles replacing the weary conventional
iconic fuels there will be no case such as running out of fuel and running short of time.

35. Military applications
 a transformation into a more responsive, deployable, and sustainable force, while
maintaining high levels of lethality, survivability and versatility.
 “TRACE photonics, U.S. Army Armaments Research, Development and Engineering
Centre” has harnessed radioisotope power sources to provide very high energy
density battery power to the men in action
 No power cords or transformers will be needed for the next generation of
microelectronics in which voltage-matched supplies are built into components .
 Safe, long-life, reliable and stable temperature is available from the direct
conversion of radioactive decay energy to electricity. This distributed energy source
is well suited to active radio frequency equipment tags, sensors and ultra wide-band
communication chips used on the modern battlefield.

36. Under water sea probes and sensors
 The recent flare up of Tsunami, Earthquakes and other underwater destructive
phenomenon has increased the demand for sensors that keeps working for a long
time and able to withstand any crude situations
 Perfect in inaccessible places or under extreme conditions, the researchers envision
its use as deep-sea probes and sensors, sub-surface, coal mines and polar sensor
application s, with a focus on the oil industry.

37. Conclusion
The world of tomorrow that science fiction dreams of and technology manifests
might be a very small one. It would reason that small devices would need small
batteries to power them. The use of power as heat and electricity from radioisotope
will continue to be indispensable. As the technology grows, the need for more
power and more heat will undoubtedly grow along with it.
Clearly the current research of nuclear batteries shows promise in future
applications for sure. With implementation of this new technology credibility and
feasibility of the device will be heightened. The principal concern of nuclear
batteries comes from the fact that it involves the use of radioactive materials. This
means throughout the process of making a nuclear battery to final disposal, all
radiation protection standards must be met. The economic feasibility of the nuclear
batteries will be determined by its applications and advantages. With several
features being added to this little wonder and other parallel laboratory works going
on, nuclear cells are going to be the next best thing ever invented in the human
history .

38. Reference
 “Power from radioisotopes,” USAEC, Division of Technical Information
 “Nuclear and radiochemistry” , Gerhardt Friedlander, Joseph.W.Kennedy and
Julian Malcolm Miller,
 “Particles and Nuclei, an Introduction to the Physical Concepts”. B.Povh, K.Rith, C.
Scolz and F.Zetche.
 Brown, Paul: "Resonant Nuclear Battery Supply", Raum & Zeit, 1(3) (August-
September, 1989
 Powerstream.com, “The Role of Chemical Power Sources in Modern Health Care”,
Curtis F. Holmes
 Powerpaper.com
 Technologyreview.com
 Wikipedia.com/ atomicbattery