NUCLEAR BATTERIES PDF
PDF | This paper reviews recent efforts in the literature to miniaturize nuclear battery systems. The potential of a nuclear battery for longer shelf-life and higher . PDF | Research groups at Cornell University and the University of Wisconsin have Their research involves developing devices, called nuclear microbatteries. atomic batteries by using nanomaterials to improve their performance. tomic batteries, nuclear batteries or radioisotope generators are devices.
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Get More Information about Nuclear Batteries PDF Download by visiting this link. Nuclear batteries use the incredible amount of energy released naturally by tiny. cooled reactor power supply known as the Nuclear Battery. Key technical features of the Nuclear Battery reactor core include a heat-pipe primary heat transport. In the past, nuclear batteries were used to power electronics for In order for a nuclear battery to function, the power source has to be a.
Fuel cells and solar cells require little maintenance, but the former are too expensive for such modest, low-power applications, and the latter need plenty of sun. Thus the demand to exploit the radioactive energy has become inevitable high. Several methods have been developed for conversion of radioactive energy released during the decay of natural radioactive elements into electrical energy.
Gallium Nitride for Nuclear Batteries
A grapefruit-sized radioisotope thermo-electric generator that utilized the heat produced from alpha particles emitted as plutonium decays was developed during the early 's. Since then the nuclear power has taken a significant consideration in the energy source of future. Also, with the advancement of the technology the requirement for lasting energy sources has been increased to a great extent.
The solution to the long term energy source is, of course, the nuclear batteries with a lifespan measured in decades and has the potential to be nearly times more efficient than the currently used ordinary batteries. These incredibly long-lasting batteries are still in the theoretical and developmental stage of existence, but they promise to provide clean, safe, almost endless energy.
Unlike conventional nuclear power generating devices, these power cells does not rely on a nuclear reaction or chemical process and does not produce radioactive waste products. The nuclear battery technology is geared toward applications where power is needed in inaccessible places or under extreme conditions.
The NAG represents a new form of nuclear power conversion technology. It represents a smaller, safer and far more efficient than any conventional nuclear power generator now in existence.
It can be used for virtually any power application from large to small hand devices. The properties of the interelectrode plasma are determined by the mode of operation of the thermionic converter. In such a device, the heat released by the decay of a suitable radioactive material is converted into electricity by the See beck effect using an array of thermocouples.
RTGs have been used as power sources in satellites, space probes and unmanned remote facilities, such as a series of lighthouses built by the former Soviet Union inside the Arctic Circle. RTGs are usually the most desirable power source for robotic or unmaintained situations needing a few hundred watts or less of power for durations too long for fuel cells, batteries, or generators to provide economically, and in places where solar cells are not practical.
Safe use of RTGs requires containment of the radioisotopes long after the productive life of the 7. Critics argue that they could cause environmental and security problems as leakage or theft of the radioactive material could pass unnoticed for years, particularly as the locations of some of these lighthouses are no longer known due to poor record keeping.
In one instance, the radioactive compartments were opened by a thief. In another case, three woodsmen in Georgia came across two ceramic RTG heat sources that had been stripped of their shielding. Two of the three were later hospitalized with severe radiation burns after carrying the sources on their backs. The units were eventually recovered and isolated.
There are approximately 1, such RTGs in Russia.
All of them have long exhausted their year engineered life spans. They are likely no longer functional, and may be in need of dismantling.
Some of them have become the prey of metal hunters, who strip the RTGs' metal casings, regardless of the risk of radioactive contamination. A basic thermophotovoltaic system consists of a thermal emitter and a photovoltaic diode cell. The emitter can be a piece of solid material or a specially engineered structure. A conventional solar cell is effectively a TPV device in which the Sun functions as the emitter. Thermal emission is the spontaneous emission of photons due to thermal motion of charges in the material.
For normal TPV temperatures, this radiation is mostly at near infrared and infrared frequencies. The photovoltaic diodes can absorb some of these radiated photons and convert them into free charge carriers, that is electricity. Thermophotovoltaic systems have few, if any, moving parts and are therefore very quiet and require low maintenance. These properties make thermophotovoltaic systems suitable for remote-site and portable electricity-generating applications. Their efficiency-cost properties, however, are often rather poor compared to other electricity-generating technologies.
Current research in the area aims at increasing the system efficiencies while keeping the system cost low. In the design of a TPV system, it is usually desired to match the optical properties of thermal emission wavelength, polarization, direction with the most efficient conversion characteristics of the photovoltaic cell, since unconverted thermal emission is a major source of inefficiency. Most groups focus on gallium antimonide GaSb cells.
Germanium Ge is also suitable.
TPV cells have often been proposed as auxiliary power conversion devices for regeneration of lost heat in other power generation systems, such as steam turbine systems or solar cells. A prototype TPV hybrid car was even built.
TPV research is a very active area. Among others, the University of Houston TPV Radioisotope Power Conversion Technology development effort is aiming at combining thermophotovoltaic cell concurrently with thermocouples to provide a 3 to 4-fold improvement in system efficiency over current radioisotope thermoelectric generators. TPVs have significant promise for efficient and economically viable power systems for both military and commercial applications. Compared to traditional nonrenewable energy sources, burner TPVs have little NOx emissions and are virtually silent.
Solar TPVs, on the other hand, are a source of entirely renewable energy with no emissions.
Compared to photovoltaics, TPVs can be more efficient owing to recycling of unabsorbed photons. However, the structure of TPVs is more complex, and losses at each energy conversion step can result in a lower efficiency than that of photovoltaics. As a result, no form of energy storage is needed. Kummer and Neill Weber at Ford in In the AMTEC sodium is driven around a closed thermodynamic cycle between a high temperature heat reservoir and a cooler reservoir at the heat rejection temperature.
The unique feature of the AMTEC cycle is that sodium ion conduction between a high pressure or activity region and a low pressure or activity region on either side of a highly ionically conducting refractory solid electrolyte, is thermodynamically nearly equivalent to an isothermal expansion of sodium vapor between the same high and low pressure.
Electrochemical oxidation of neutral sodium at the anode leads to sodium ions which traverse the solid electrolyte and electrons which travel from the anode through an external circuit where they The sodium gas generated at the cathode then travels to a condenser at the heat rejection temperature of perhaps — K where liquid sodium reforms.
The AMTEC thus is an electrochemical concentration cell which converts the work generated by expansion of sodium vapor directly into electric power. The converter is based on the electrolyte used in the sodium-sulfur battery, sodium beta"alumina, a crystalline phase of somewhat variable composition containing aluminum oxide, Al2O3, and sodium oxide, Na2O, in a nominal ratio of 5: The sodium beta"-alumina solid electrolyte BASE [ceramic] is nearly insulating with respect to transport of electrons, and is a thermodynamically stable phase in contact with both liquid sodium and sodium at low pressure.
AMTEC requires energy input at modest elevated temperatures, and not at a specific wavelength, it is easily adapted to any heat source, including radioisotope, concentrated solar, external combustion, or nuclear reactor. A solar thermal power conversion system based on an AMTEC has advantages over other technologies including photovoltaic systems in terms of the total power that can be achieved with such a system and the simplicity of the system which includes the collector, energy storage thermal storage with phase change material and power conversion in a compact unit.
The energy storage system outperforms batteries, and the temperatures at which the system operates allows long life and reduced radiator size heat reject temperature of K. Deep-space applications would use radioisotope thermoelectric generators; hybrid systems are in design. While space power systems are of intrinsic interest, terrestrial applications will offer large scale applications for AMTEC systems.
The potential to scavenge waste heat may allow for integration of this technology into general residential and commercial cogeneration schemes although costs per kilowatt-hour would have to drop substantially from current projections. Their outputs are not functions of temperature differences as are thermoelectric and thermionic converters. Non-thermal generators can be grouped into five classes. Spacing can be either vacuum or dielectric.
Negatively charged beta particles or positively charged alpha particles, positrons or fission fragments may be utilized. Although this form of nuclear-electric generator dates back to , few applications have been found in the past for the extremely low currents and inconveniently high voltages provided by direct charging generators.
English physicist H. Moseley constructed the first of these. The charged particles from the radium created a flow of electricity as they moved quickly from the radium to the inside surface of the sphere.
As late as the Moseley model guided other efforts to build experimental batteries generating electricity from the emissions of radioactive elements. A common source used is the hydrogen isotope, tritium. Unlike most nuclear power sources, which use nuclear radiation to generate heat, which then is used to generate electricity thermoelectric and thermionic sources , betavoltaics use a non-thermal conversion process; converting the electron-hole pairs produced by the ionization trail of beta particles traversing a semiconductor.
Betavoltaic power sources are particularly well-suited to low-power electrical applications where long life of the energy source is needed, such as implantable medical devices or military and space applications. The primary use for betavoltaics is for remote and long-term use, such as spacecraft requiring electrical power for a decade or two. Recent progress has prompted some to suggest using betavoltaics to trickle-charge conventional batteries in consumer devices, such as cell phones and laptop computers.
As early as , betavoltaics were suggested for use in long-term medical devices such as pacemakers.
Although betavoltaics use a radioactive material as a power source, the beta particles used are low energy and easily stopped by shielding, as compared to the gamma rays generated by more dangerous radioactive materials. With proper device construction that is, proper containment , a betavoltaic device would not emit dangerous radiation. Leakage of the enclosed material would engender health risks, just as leakage of the materials in other types of batteries leads to significant health and environmental concerns.
As radioactive material emits, it slowly decreases in activity. Thus, over time a betavoltaic device will provide less power. For practical devices, this decrease occurs over a period of many years. For tritium devices, the half-life is In device design, one must account for what battery characteristics are required at end-of-life, and ensure that the beginning-of-life properties take into account the desired usable lifetime.
Liability connected with environmental laws and human exposure to tritium and its beta decay must also be taken into consideration during risk assessment and product development.
Naturally, this increases both time-to-market and the already high cost associated with tritium. A report by the UK government's Health Protection Agency Advisory Group on Ionizing Radiation declared the health risks of tritium exposure to be double those previously set by the International Commission on Radiological Protection located in Sweden. A beta-emitter such as technetium or strontium is suspended in a gas or liquid containing luminescent gas molecules of the excimer type, constituting a "dust plasma.
The electrons then excite the gases whose excimer line is selected for the conversion of the radioactivity into a surrounding photovoltaic layer such that a lightweight, lowpressure, high-efficiency battery can be realised.
These nuclides are relatively low-cost radioactive waste from nuclear power reactors. The diameter of the dust particles is so small a few micrometers that the electrons from the beta decay leave the dust particles nearly without loss. The surrounding weakly ionized plasma consists of gases or gas mixtures such as krypton, argon, and xenon with excimer 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 as e. The battery would consist of an excimer of argon, xenon, or krypton or a mixture of two or three of them in a pressure vessel with an internal mirrored surface, finely-ground radioisotope, and an intermittent ultrasonic stirrer, illuminating a photocell with a bandgap tuned for the excimer. When the beta active nuclides e. The electric power per weight compared with existing radionuclide batteries can then be increased by a factor 10 to 50 and more.
The 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 battery's net power. This approach creates a high-impedance source and, unlike chemical batteries, the devices will work in a very wide range of temperatures. A piezoelectric cantilever is mounted directly above a base of the radioactive isotope nickel All of the radiation emitted as the millicurie-level nickel thin film decays is in the form of beta radiation, which consists of electrons.
As the cantilever accumulates the emitted electrons, it builds up a negative charge at the same time that the isotope film becomes positively charged. The beta particles essentially transfer electronic charge from the thin film to the cantilever. The opposite charges cause the cantilever to bend toward the isotope film.
Nuclear Batteries and Radioisotopes
Just as the cantilever touches the thin-film isotope, the charge jumps the gap. That permits current to flow back onto the isotope, equalizing the charge and resetting the cantilever. As long as the isotope is decaying - a process that can last for decades - the tiny cantilever will continue its up-and-down motion.
As the cantilever directly generates electricity when deformed, a charge pulse is released each time the cantilever cycles. Radioactive isotopes can continue to release energy over periods ranging from weeks to decades. The half-life of nickel, for example, is over years. Thus, a battery using this isotope might continue to supply useful energy for at least half that time. Radioisotope piezoelectric generator Avoidance of gamma in the decay chain Half life Particle range Watch out for alpha, n reactions Any radioisotope in the form of a solid that gives off alpha or beta particles can be utilized in the nuclear battery.
The first cell constructed that melted the wire components employed the most powerful source known, radium, as the energy source. However, radium gives rise through decay to the daughter product bismuth, which gives off strong gamma radiation that requires shielding for safety. This adds a weight penalty in mobile applications. Radium is a naturally occurring isotope which is formed very slowly by the decay of uranium Radium in equilibrium is present at about 1 gram per 3 million grams of uranium in the earths crust.
Uranium mill wastes are readily available source of radium in very abundant quantities. Uranium mill wastes contain far more energy in the radium than is represented by the fission energy derived form the produced uranium. Strontium gives off no gamma radiation so it does not necessitate the use of thick lead shielding for safety.
The utilizable energy from strontium substantially exceeds the energy derived from the nuclear fission which gave rise to this isotope. Once the present stores of nuclear wastes have been mined, the future supplies of strontium will depend on the amount of nuclear electricity generated hence strontium decay may ultimately become a premium fuel for such special uses as for perpetually powered wheel chairs and portable computers.
Plutonium dioxide is used for space application. Half life of In its ground state, tantalum Ta is very unstable and decays to other nuclei in about 8 hours but its isomeric state, m Ta, is found in natural samples.
Tantalum m hence can be used for switchable nuclear batteries. This is whopping when considered that it provides non stop electric energy for the seconds spanning these 10long years, which may simply mean that we keep our laptop or any hand held devices switched-on for 10 years nonstop.
Contrary to fears associated with conventional batteries nuclear cells offers reliable electricity, without any drop in the yield or potential during its entire operational period. Thus the longevity and reliability coupled together would suffice the small factored energy needs for at least a couple of decades. The largest 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. Balancing the safety measures such as shielding and regulation while still keeping the size and power advantages will determine the economic feasibility of nuclear batteries. Safeties with respect to the containers are also adequately taken care as the battery cases are hermetically sealed.
Thus the risk of safety hazards involving radioactive material stands reduced. 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. Similarly, the efficiency of such cells is much higher simply because radioactive materials in little waste generation. 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.
This should come as a handy savior for almost all developed and developing nations. For example strontium does not exist in nature but it is one of the several radioactive waste products resulting from nuclear fission. DRAWBACKS 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.
The size of nuclear batteries for certain specific applications may cause problems, but can be done away with as time goes by.
For example, size of Xcell used for laptop battery is much more than the conventional battery used in the laptops. Though radioactive materials sport high efficiency, the conversion methodologies used presently are not much of any wonder and at the best matches conventional energy sources. However, laboratory results have yielded much higher efficiencies, but are yet to be released into the alpha stage.
A minor blow may come in the way of existing regional and country specific laws regarding the use and disposal of radioactive materials.
As these are not unique worldwide and are subject to political horrors and ideology prevalent in the country. The introduction legally requires these to be scrapped or amended.
It can be however be hoped that, given the revolutionary importance of this substance, things would come in favor gradually.Upcoming SlideShare. When the current flows in electrical circuit.
So the scientists had to find some other ways of converting nuclear energy into electric energy.
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The opposite charges cause the cantilever to bend toward the isotope film. It is reported that about These results support the validity of the hydrogen-induced dipole layer model.
It is then covered with a black box to shield it from the light. The electric circuit used for these experiments is shown below. Direct charging generators In this type. First the beta particles, which are high-energy electrons, fly spontaneously from the radioactive source.
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