Final Report On Nuclear Reaction

Table of content • • • • • • • • • •

Introduction Discovery Nuclear Fission Nuclear Fusion Nuclear Power Uses of nuclear power Nuclear Accidents Nuclear weapons Types of nuclear reaction Examples of nuclear technology 1. Nuclear Technology 2. Medical Applications 3. Industrial Application 4. Commercial Applications 5. Food processing & agriculture • Economics of Nuclear Technology • Pros and Cons of Nuclear Energy

Introduction: In nuclear physics, a nuclear reaction is the process in which two nuclei or nuclear particles collide to produce products different from the initial particles. In principle a reaction can involve more than two particles colliding, but because the probability of three or more nuclei to meet at the same time at the same place is much less than for two nuclei, such an event is exceptionally rare. While the transformation is spontaneous in the case of radioactive decay, it is initiated by a particle in the case of a nuclear reaction. If the particles collide and separate without changing, the process is called an elastic collision rather than a reaction.

In the symbolic figure shown to the right, 63Li and deuterium react to form the highly excited intermediate nucleus 84Be which then decays immediately into two alpha particles. Protons are symbolically represented by red spheres, and neutrons by blue spheres. 63Li

+

21H

→

42He

+ ?

To make the sums correct, the second nucleus to the right must have atomic number 2 and mass number 4; it is therefore also Helium-4. The complete equation therefore reads: 63Li

+

21H

→

42He

+

or more simply: 63Li

+

21H

→ 2 42He

42He

Discovery: In 1896, Henri Becquerel was investigating phosphorescence in uranium salts when he discovered a new phenomenon which came to be called radioactivity.[1] He, Pierre Curie and Marie Curie began investigating the phenomenon. In the process they isolated the element radium, which is highly radioactive. They discovered that radioactive materials produce intense, penetrating rays of several distinct sorts, which they called alpha rays, beta rays and gamma rays. Some of these kinds of radiation could pass through ordinary matter, and all of them could cause damage in large amounts - all the early researchers received various radiation burns, much like sunburn, and thought little of it. The new phenomenon of radioactivity was seized upon by the manufacturers of quack medicine (as had the discoveries of electricity and magnetism, earlier), and any number of patent medicines and treatments involving radioactivity were put forward. Gradually it came to be realized that the radiation produced by radioactive decay was ionizing radiation, and that quantities too small to burn presented a severe long-term hazard. Many of the scientists working on radioactivity died of cancer as a result of their exposure. Radioactive patent medicines mostly disappeared, but other applications of radioactive materials persisted, such as the use of radium salts to produce glowing dials on meters. As the atom came to be better understood, the nature of radioactivity became clearer; some atomic nuclei are unstable, and can decay releasing energy in the form of gamma rays (high-energy photons), alpha particles (a pair of protons and a pair of neutrons) and beta particles, high-energy electrons.

Nuclear fission: Radioactivity is generally a slow and difficult process to control, and is unsuited to building a weapon. However, other nuclear reactions are possible. In particular, a sufficiently unstable nucleus can undergo nuclear fission, breaking into two smaller nuclei and releasing energy and some fast neutrons. This neutron could, if captured by another nucleus, cause that nucleus to undergo fission as well. The process could then continue in a nuclear chain reaction. Such a chain reaction could release a vast amount of energy in a short amount of time. When discovered on the eve of World War II, it led multiple countries to begin programs investigating the possibility of constructing an atomic bomb—a weapon which utilized fission reactions to generate far more energy than could be created with chemical explosives. The Manhattan Project, run by the United States with the help of the United Kingdom and Canada, developed multiple fission weapons which were used against Japan in 1945. During the project, the first fission reactors were developed as well, though they were primarily for weapons manufacture and did not generate power.

Nuclear fusion: Nuclear fusion technology was initially pursued only in theoretical stages during World War II, when scientists on the Manhattan Project (led by Edward Teller) investigated the possibility of using the great power of a fission reaction to ignite fusion reactions. It took until 1952 for the first full detonation of a hydrogen bomb to take place, so-called because it utilized reactions between deuterium and tritium, isotopes of hydrogen. Fusion reactions are much more energetic per unit mass of fusion material, but it is much more difficult to ignite a chain reaction than is fission. Research into the possibilities of using nuclear fusion for civilian power generation was begun during the 1940s as well. Technical and theoretical difficulties have hindered the development of working civilian fusion technology, though research continues to this day around the world.

Nuclear Power Nuclear power is any nuclear technology designed to extract usable energy from atomic nuclei via controlled nuclear reactions. The only method in use today is through nuclear fission, though other methods might one day include nuclear fusion and radioactive decay (see below). All utility-scale reactorsheat water to produce steam, which is then converted into mechanical work for the purpose of generating electricity or propulsion. In 2007, 14% of the world's electricity came from nuclear power. More than 150 nuclear-powered naval vessels have been built, and a few radioisotope rockets have been produced.

Uses: As of 2005, nuclear power provided 6.3% of the world's energy and 15% of the world's electricity, with the U.S., France, and Japan together accounting for 56.5% of nuclear generated electricity. As of 2007, the IAEA reported there are 439 nuclear power reactors in operation in the world, operating in 31 countries. In 2007, nuclear power´s share of global electricity generation dropped to 14%. According to the International Atomic Energy Agency, the main reason for this was an earthquake in western Japan on 16 July 2007, which shut down all seven reactors at the Kashiwazaki-Kariwa Nuclear Power Plant. There were also several other reductions and "unusual outages" experienced in Korea and Germany. Also, increases in the load factor for the current fleet of reactors appear to have plateaued. The United States produces the most nuclear energy, with nuclear power providing 19% of the electricity it consumes, while France produces the highest

percentage of its electrical energy from nuclear reactors—78% as of 2006. In the European Union as a whole, nuclear energy provides 30% of the electricity. Nuclear energy policy differs between European Union countries, and some, such as Austria, Estonia, and Ireland, have no active nuclear power stations. In comparison, France has a large number of these plants, with 16 multi-unit stations in current use. In the US, while the Coal and Gas Electricity industry is projected to be worth $85 billion by 2013, Nuclear Power generators are forecast to be worth $18 billion. Many military and some civilian (such as some icebreaker) ships use nuclear marine propulsion, a form of nuclear propulsion. A few space vehicles have been launched using full-fledged nuclear reactors: the Soviet RORSAT series and the American SNAP-10A. International research is continuing into safety improvements such as passively safe plants, the use of nuclear fusion, and additional uses of process heat such as hydrogen production (in support of a hydrogen economy), for desalinating sea water, and for use in district heating systems.

Nuclear Accidents In some cases, a release of radioactive contamination occurs, but in many cases the accident involves a sealed source or the release of radioactivity is small while the direct irradiation is large. Due to government and business secrecy, it is not always possible to determine with certainty the frequency or the extent of some events in the early days of the radiation industries. Modern misadventures, accidents, and incidents, which result in injury, death, or serious environmental contamination, tend to be well documented by the International Atomic Energy Agency Because of the different nature of the events it is best to divide the list into nuclear and radiation accidents. An example of nuclear accident might be one in which a reactor core is damaged such as in the Chernobyl Nuclear Power Plant Accident, while an example of a radiation accident might be some event such as a radiography accident where a worker drops the source into a river. These radiation accidents such as those involving the radiography sources often have as much or even greater ability to cause serious harm to both workers and the public than the well known nuclear accidents. Radiation accidents are more common than nuclear accidents, and are often limited in scale. For instance at Soreq, a worker suffered a dose which was similar to one of the highest doses suffered by a worker on site at Chernobyl on

day one. However, because the gamma source was never able to leave the 2metre thick concrete enclosure, it was not able to harm many others. The web page at the International Atomic Energy Agency, which deals with recent accidents is. The safety significance of nuclear accidents can be assessed and conveyed using the International Atomic Energy Agency International Nuclear Event Scale. Nuclear Regulatory Commission Headquarters and Regional staff members typically participate in four full-scale and emergency response exercises each year, selected from among the list of full-scale Federal Emergency Management Agency (FEMA)-graded exercises required of nuclear facilities. Regional staff members and selected Headquarters staff also participate in post-plume, ingestion phase response exercises. On-scene participants include the NRC licensee, and State, county, and local emergency response agencies. This allows for Federal Interagency participation that will provide increased preparedness during the potential for an event at an operating nuclear reactor.

Nuclear Weapons The design of a nuclear weapon is more complicated than it might seem; it is quite difficult to ensure that such a chain reaction consumes a significant fraction of the fuel before the device flies apart. The construction of a nuclear weapon is also more difficult than it might seem, as no naturally occurring substance is sufficiently unstable for this process to occur. One isotope of uranium, namely uranium-235, is naturally occurring and sufficiently unstable, but it is always found mixed with the more stable isotope uranium-238. Thus a complicated and difficult process of isotope separation must be performed to obtain uranium-235. Alternatively, the element plutonium possesses an isotope that is sufficiently unstable for this process to be usable. Plutonium does not occur naturally, so it must be manufactured in a nuclear reactor. Ultimately, the Manhattan Project manufactured nuclear weapons based on each of these. The first atomic bomb was detonated in a test code-named "Trinity", near Alamogordo on July 16, 1945. After much debate on the morality of using such a horrifying weapon, two bombs were dropped on the Japanese cities Hiroshima and Nagasaki, and the Japanese surrender followed shortly. Several nations began nuclear weapons programs, developing ever more destructive bombs in an arms race to obtain what many called a nuclear deterrent. Nuclear weapons are the most destructive weapons known - the archetypal weapons of mass destruction. Throughout the Cold War, the opposing powers had huge nuclear arsenals, sufficient to kill hundreds of millions of people. Generations of people grew up under the shadow of nuclear devastation.

However, the tremendous energy release in the detonation of a nuclear weapon also suggested the possibility of a new energy source.

Types of nuclear reaction Most natural nuclear reactions fall under the heading of radioactive decay, where a nucleus is unstable and decays after a random interval. The most common processes by which this can occur are alpha decay, beta decay, and gamma decay. Under suitable circumstances, a large unstable nucleus can break into two smaller nuclei, undergoing nuclear fission. If these neutrons are captured by a suitable nucleus, they can trigger fission as well, leading to a chain reaction. A mass of radioactive material large enough (and in a suitable configuration) is called a critical mass. When a neutron is captured by a suitable nucleus, fission may occur immediately, or the nucleus may persist in an unstable state for a short time. If there are enough immediate decays to carry on the chain reaction, the mass is said to be prompt critical, and the energy release will grow rapidly and uncontrollably, usually leading to an explosion. However, if the mass is critical only when the delayed neutrons are included, the reaction can be controlled, for example by the introduction or removal of neutron absorbers. This is what allows nuclear reactors to be built. Fast neutrons are not easily captured by nuclei; they must be slowed (slow neutrons), generally by collision with the nuclei of a neutron moderator, before they can be easily captured. If nuclei are forced to collide, they can undergo nuclear fusion. This process may release or absorb energy. When the resulting nucleus is lighter than that of iron, energy is normally released; when the nucleus is heavier than that of iron, energy is generally absorbed. This process of fusion occurs in stars, and results in the formation, in stellar nucleosynthesis, of the light elements, from lithium to calcium, as well as some formation of the heavy elements, beyond Iron and Nickel, which cannot be created by nuclear fusion, via neutron capture - the Sprocess. The remaining abundance of heavy elements - from Nickel to Uranium and beyond - is due to supernova nucleosynthesis, the R-process. Of course, these natural processes of astrophysics are not examples of nuclear technology. Because of the very strong repulsion of nuclei, fusion is difficult to achieve in a controlled fashion. Hydrogen bombs obtain their enormous destructive power from fusion, but obtaining controlled fusion power has so far proved elusive. Controlled fusion can be achieved in particle accelerators; this is how many synthetic elements were produced. The Farnsworth-Hirsch Fusor is a device which can produce controlled fusion (and which can be built as a high-school science project), albeit at a net energy loss. It is sold commercially as a neutron source.

The vast majority of everyday phenomena do not involve nuclear reactions. Most everyday phenomena only involve gravity and electromagnetism. Of the fundamental forces of nature, they are not the strongest, but the other two, the strong nuclear force and the weak nuclear force are essentially short-range forces so they do not play a role outside the atomic nucleus. Atomic nuclei are generally kept apart because they contain positive electrical charges and therefore repel each other, so in ordinary circumstances they cannot meet.

Examples of Nuclear Technology: Medical Applications The medical applications of nuclear technology are divided into diagnostics and radiation treatment. Imaging - medical and dental x-ray imagers use of Cobalt-60 or other x-ray sources. Technetium-99m is used, attached to organic molecules, as radioactive tracer in the human body, before being excreted by the kidneys. Positron emitting nucleotides are used for high resolution, short time span imaging in applications known as Positron emission tomography. Radiation therapy is an effective treatment for cancer.

Industrial applications Oil and Gas Exploration- Nuclear well logging is used to help predict the commercial viability of new or existing wells. The technology involves the use of a neutron or gamma-ray source and a radiation detector which are lowered into boreholes to determine the properties of the surrounding rock such as porosity and lithography.[1] Road Construction - Nuclear moisture/density gauges are used to determine the density of soils, asphalt, and concrete. Typically a Cesium-137 source is used.

Commercial applications An ionization smoke detector includes a tiny mass of radioactive americium-241, which is a source of alpha radiation. Tritium is used with phosphor in rifle sights to increase nighttime firing accuracy. Luminescent exit signs use the same technology.[3]

Food Processing and Agriculture

The Radura logo, used to show a food has been treated with ionizing radiation. Food irradiation[4] is the process of exposing food to ionizing radiation in order to destroy microorganisms, bacteria, viruses, or insects that might be present in the food. The radiation sources used include radioisotope gamma ray sources, X-ray generators and electron accelerators. Further applications include sprout inhibition, delay of ripening, increase of juice yield, and improvement of rehydration. Irradiation is a more general term of deliberate exposure of materials to radiation to achieve a technical goal (in this context 'ionizing radiation' is implied). As such it is also used on non-food items, such as medical hardware, plastics, tubes for gas-pipelines, hoses for floor-heating, shrink-foils for food packaging, automobile parts, wires and cables (isolation), tires, and even gemstones. Compared to the amount of food irradiated, the volume of those every-day applications is huge but not noticed by the consumer. The genuine effect of processing food by ionizing radiation relates to damages to the DNA, the basic genetic information for life. Microorganisms can no longer proliferate and continue their malignant or pathogen activities. Spoilage causing micro-organisms cannot continue their activities. Insects do not survive or become incapable of procreation. Plants cannot continue the natural ripening or aging process. All these effects are beneficial to the consumer and the food industry, likewise.[4] It should be noted that the amount of energy imparted for effective food irradiation is low compared to cooking the same; even at a typical dose of 10 kGy most food, which is (with regard to warming) physically equivalent to water, would warm by only about 2.5 °C. The specialty of processing food by ionizing radiation is the fact, that the energy density per atomic transition is very high, it can cleave molecules and induce ionization (hence the name) which cannot be achieved by mere heating. This is the reason for new beneficial effects, however at the same time, for new concerns. The treatment of solid food by ionizing radiation can provide an effect similar to heat pasteurization of liquids, such as milk. However, the use of the term, cold pasteurization, to describe irradiated foods is controversial, because

pasteurization and irradiation are fundamentally different processes, although the intended end results can in some cases be similar. Food irradiation is currently permitted by over 40 countries and volumes are estimated to exceed 500 000 metric tons annually world wide. [5] [6] [7] It should be noted that food irradiation is essentially a non-nuclear technology; it relies on the use of ionizing radiation which may be generated by accelerators for electrons and conversion into bremsstrahlung, but which may use also gammarays from nuclear decay. There is a world-wide industry for processing by ionizing radiation, the majority by number and by processing power using accelerators. Food irradiation is only a niche application compared to medical supplies, plastic materials, raw materials, gemstones, cables and wires, etc.

Economics of Nuclear Technology The Economics of Nuclear Power

Electricity Generation Nuclear Technology can also be used to produce ELECTRICITY which is very important according to economical condition of a country. Nuclear plant can produce more electricity than thermal or hydro electric plant. Isotope produced using Nuclear Technology is used in many chemical and pharma companies. 1) Nuclear power is cost competitive with other forms of electricity generation, except where there is direct access to low-cost fossil fuels. 2) Fuel costs for nuclear plants are a minor proportion of total generating costs, though capital costs are greater than those for coal-fired plants. 3) In assessing the cost competitiveness of nuclear energy, decommissioning and waste disposal costs are taken into account. The relative costs of generating electricity from coal, gas and nuclear plants vary considerably depending on location. Coal is, and will probably remain, economically attractive in countries such as China, the USA and Australia with abundant and accessible domestic coal resources as long as carbon emissions are cost-free. Gas is also competitive for base-load power in many places, particularly using combined-cycle plants, though rising gas prices have removed much of the advantage. Nuclear energy is, in many places, competitive with fossil fuel for electricity generation, despite relatively high capital costs and the need to internalise all waste disposal and decommissioning costs. If the social, health and environmental costs of fossil fuels are also taken into account, nuclear is outstanding.

The cost of fuel From the outset the basic attraction of nuclear energy has been its low fuel costs compared with coal, oil and gas fired plants. Uranium, however, has to be processed, enriched and fabricated into fuel elements, and about two thirds of the cost is due to enrichment and fabrication. Allowances must also be made for the management of radioactive spent fuel and the ultimate disposal of this spent fuel or the wastes separated from it. But even with these included, the total fuel costs of a nuclear power plant in the OECD are typically about a third of those for a coal-fired plant and between a quarter and a fifth of those for a gas combined-cycle plant. Fuel costs are one area of steadily increasing efficiency and cost reduction. For instance, in Spain nuclear electricity cost was reduced by 29% over 1995-2001. This involved boosting enrichment levels and burn-up to achieve 40% fuel cost reduction. Prospectively, a further 8% increase in burn-up will give another 5% reduction in fuel cost.

Comparing electricity generation For nuclear power plants any cost figures normally include spent fuel management, plant decommissioning and final waste disposal. These costs, while usually external for other technologies, are internal for nuclear power. Decommissioning costs are estimated at 9-15% of the initial capital cost of a nuclear power plant. But when discounted, they contribute only a few percent to the investment cost and even less to the generation cost. In the USA they account for 0.1-0.2 cent/kWh, which is no more than 5% of the cost of the electricity produced. The back-end of the fuel cycle, including spent fuel storage or disposal in a waste repository, contributes up to another 10% to the overall costs per kWh, - less if there is direct disposal of spent fuel rather than reprocessing. The $18 billion US spent fuel program is funded by a 0.1 cent/kWh levy. French figures published in 2002 show (EUR cents/kWh): nuclear 3.20, gas 3.054.26, coal 3.81-4.57. Nuclear is favourable because of the large, standardised plants used. The cost of nuclear power generation has been dropping over the last decade. This is because declining fuel (including enrichment), operating and maintenance costs, while the plant concerned has been paid for, or at least is being paid off. In general the construction costs of nuclear power plants are significantly higher than for coal- or gas-fired plants because of the need to use special materials, and to incorporate sophisticated safety features and back-up control equipment. These contribute much of the nuclear generation cost, but once the plant is built the variables are minor. In the past, long construction periods have pushed up financing costs. In Asia

construction times have tended to be shorter, for instance the new-generation 1300 MWe Japanese reactors which began operating in 1996 and 1997 were built in a little over four years. Overall, OECD studies in teh 1990s showed a decreasing advantage of nuclear over coal. This trend was largely due to a decline in fossil fuel prices in the 1980s, and easy access to low-cost, clean coal, or gas. In the 1990s gas combined-cycle technology with low fuel prices was often the lowest cost option in Europe and North America. But the picture is changing.

The Pros and Cons of Nuclear Energy: The applications of nuclear reactors as our main power source for the future is a huge subject of debate, named The Nuclear Debate. The generation of nuclear power from nuclear fuel for civilian purposes is a quest that 21 one companies are taking on for the first time since 1973. The Nuclear Regulatory Commission reports they will seek permission to build 34 power plants from New York to Texas. Multi billion dollar investments that were riding on the choice of an energy source are now being funneled into new nuclear energy projects costing several billion dollars for each plant. Supports claim new nuclear plants are needed because of the variable needs for different amounts of energy to be stored and released at different times. This is also known as base power. Hydroelectricity comes close with it?s man made dam control that allows us to release more power as needed but as the natural conditions must be in place the potential for stored nuclear power is so much greater. Nuclear energy supporters claim back up sources are necessary with other forms of energy like wind and solar because they fail to produce a constant supply or surplus of energy that is offered by nuclear power. The primary environment impacts of nuclear power come from Uranium mining, radioactive emissions and heat waste. The greenhouse gas emissions produced thru the nuclear fuel cycle are only a fraction of those produced by fossil fuels. However, new nuclear power plants are considered unfavorable by anti-nuclear organizations because of the initial cost of constructing them and the fact that a new plant will take 10 years to build. Because each plant costs several billion US dollars it is hard to imagine that money will be left over for research which could make plants cheaper and more efficient. To get an idea of the scope of building that would be necessary if we wanted to count on getting 80% of our energy from nuclear fission, we would need thousands of new plants. Nuclear development is therefore conceivable on the scale necessary only if it is backed by inappropriately large economic subsidies in the form of taxpayer funded research and development and risks. Public subsidies and tax expenditures involved in research and security. The

decommissioning of a nuclear facility has unforeseen potential costs as we do not know what it may cost to dispose, safely of the nuclear waste and the taxpayers might pay for this risk. With new nuclear plant building beginning again, alternative energy source development advocates are also worried about the lack of research and development for other power sources. Because of the massive power potential of nuclear energy there is a danger that there could be a lock-in effect or the creation of market entry barriers for other sources of energy like solar and wind energy. Other competing energy sources still receive large direct production subsides and tax breaks in many nations. As long as the subsidies continue to be given for alternative energy sources while we enter a new ten year nuclear energy plant construction period, energy solutions can come from many alternative sources both corporate and homespun, yet none with as much energy potential and on the massive scale of nuclear energy development.