Major Evaluating Report for batteries of Radioactive Kind1. Introduction The search for alternative energy sources has led to research in many different fields. One of the modern concepts is the idea of a battery that, instead of utilizing the energy in a chemical gradient like a dry cell battery, uses the energy given off by natural radioactive decay of an isotope to create an electric current. This type of cell is called a nuclear battery. In order for a nuclear battery to function, the power source has to be a radioactive isotope. An isotope is a nuclide of an element with a different mass due to a different number of neutrons. The decay of a nucleus to form other nuclides by emitting different types of particles, electromagnetic radiation, as well as heat, is known as radioactivity. The stability of an isotope depends on the ratio of protons to neutrons and a Line of Stability that describes the radioactivity of isotopes. The time scale for radioactivity to occur is different among isotopes and their decay can be measured in terms of how long it takes for half of the original element to decay to another element. This value is known as the half-life or t1/2. decay is a type of process that certain elements may go through depending on the ratio of protons to neutrons inside the nucleus. Neutron Proton + electron (Energy) The mass of the particles in this equation is conserved. When this reaction occurs, the product electron is ejected with some kinetic energy from the nucleus and is known as a particle.This idea becomes vital for the function of the modular nuclear battery because the natural decay of a - emitting particle is the primary source of energy. This electron can be used to cause a type of chain reaction, or flow of other electrons, that can be harnessed as electrical energy. The rate of flow of electrons through a medium is known as a current.The most important type of material relative to the function of a nuclear battery is the semiconductor. The special properties of semiconductors allow the harnessing of radioactive energy from the decay of radioisotopes that release of particles. Semiconductors are materials that contain properties that fall in between conductors and insulators. Conduction in semiconductors can occur in multiple ways.2. HistoryHenry Mosley, in 1912 attempted to use high positive voltages to pull beta particles (high energy electrons) back into their radioactive source. The positive charge on radium increases when it loses negative charges by beta-particle emission. The lack of perfect insulation then limited the generated potential to 150,000V. Moseley actually created the worlds first atomic battery a beta cell. He called it a radium battery. Such a battery relied on using the charge on beta or alpha particles to directly derive a current. This was done by collecting the charges of radioactive decay on a metal and using a capacitive structure to drive a current.3. ClassificationCurrently, nuclear batteries can be separated into two main categories: Non-thermal Converting Batteries and Thermal Converting Batteries.3.1. Thermal Converting Battery An example of thermal converting battery is Radioisotope Thermo-electric Generator (RTG). RTGs, like other nuclear batteries, essentially have no moving parts. They generate electricity by utilizing the heat released from radioactive decay. Heat from decay is generated by many unstable isotopes, including byproducts of nuclear fission capable of radiating heat for decades. This heat source conducts onto a thermo-electric generator. The heat-to-electricity conversion occurs when two different conducting metals are joined together to create a closed circuit and the two junctions are kept at different temperatures. The temperature differential is brought about by utilizing the radioisotope to transfer more heat to one metal conductor while the other is less hot. (Barnov, 2011)3.2. Non Thermal Converting Battery Non-thermal Converting Batteries extract incident energy of radioactive decay and does not depend on a temperature differential. There are three existing types of non-thermal converting atomic batteries that have been developed.3.2.1. Optoelectric BatteryThe first type is the Optoelectric Battery, which involves turning the beta decay of radionuclides to light and then the conversion of light into electrical energy (photovoltaics). Isotopes are suspended in gas that is capable of being excited by emitted electrons. The chosen gases then emit light that is of certain wavelength, which is then used to excite a PN-junction in a photovoltaic cell to produce an electric current. Technetium-99 and Strontium-90 have both been used as the radioisotope and the gases used may be a mixture of argon, xenon, and krypton for the production of this type of battery (Lao, 2011)3.2.2. Radioisotope Piezoelectric BatteryThe second type is the Radioisotope Piezoelectric Battery (RPB). Piezoelectricity is the linear accumulation of electric charge due to mechanical stress or pressure directly due to the Piezoelectric Effect. The reverse Piezoelectric Effect is what drives the RPB, using an electric field and mechanical energy to produce a current. Nickel-63 is usually used for this process. . This isotope emits beta particles towards the cantilever, which gradually builds an electric charge. At the same time, the film of nickel isotope builds a positive charge. With building potential cantilever and film come in contact and a flow of current is established. (Li H., 2002) 3.2.3. Betavoltaic CellThe third kind of Non-thermal Converting Nuclear Battery is the betavoltaic cell. Analogous to a photovoltaic cell, the betavoltaic cell operates on the same principle, but generates energy from a beta-emitting radioisotope instead of light. When the isotope radiates toward a PN-junction, it creates holes pairs in the semiconductor material, which in turn generates a current due to the voltaic effect. Recent research in betavoltaics has also increased the efficiency of the conversion system. Modern technology allowed to increase the surface area of semiconductor material to absorb particles, this increase resulting in higher efficiency. (Lao, 2011)4. DrawbacksHigh price, low conversion efficiency, Disposal and harmful effects of radioactive substance weighs in heavily on public and hence it is first essential for the new technology to gain social acceptance which is can do so by demonstrating its benefits and safe operations of the batteries.5. ApplicationsNuclear batteries find many fold applications due to its long life and improved reliability. Space, medical, underwater exploration are the filled which will be greatly benefitted by advancements in nuclear battery technology. In space applications, nuclear power units offer advantages over solar cells, fuel cells and ordinary batteries as they provide high power, a high life time, a compact design and are independent of atmospheric conditions. The medical field finds a lot of applications with the nuclear battery due to their increased longevity and better reliability. Nuclear batteries may slowly replacing the conventional batteries and adaptors. Since these batteries are geared towards applications where power is needed in inaccessible places or under extreme conditions, researchers envision its use as deep-sea probes and sensors.6. ConclusionAs the world grows, the need for more power and 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, nuclear cells are going to be the next best thing ever invented in human history. 7. BibliographyA, T. (1999). Nuclear Batteries: Types and Possible Uses. Nucleonics, 129-133.Barnov, V. (2011). Super Compact Radio Nuclide. Vancouver.Blanchard, J. (2005). Radioisotope Batteries for MEMS. Wisconsin.Lao, R. (2011). A Modular Design for Nuclear Battery Technology. San Luis.Li H., L. A. (2002). Self-reciprocating Radioisotope-Powered Cantilever. Wisconcin: J. Appl. Phys.