Presentation on theme: "Nuclear Energy Sergei Zverev, Ph.D. The Ingenuity Project"— Presentation transcript:
Nuclear Energy Sergei Zverev, Ph.D. The Ingenuity Project
quadrillion btu = × joules US Energy Consumption by Source US Energy Consumption and Production Source: EIA US Energy Consumption by Industry USA : 4.5 % of world population 21% of world energy consumption
World Energy Consumption by Source quadrillion btu = × joules World Population Millions of people Source: UN Source: EIA The wide use of fossil fuels has been one of the most important stimuli of economic growth and prosperity since the industrial revolution.
World Crude Oil Discoveries and Production US Crude Oil Production and Imports US Crude Oil Production In 1956, Hubbert proposed that fossil fuel production would follow a bell-shaped curve (Hubbert curve) for production P which can be approximated with World Crude Oil and Gas Production Coal. Recent estimates suggest that global coal production could peak in as few as 15 years. After the peak, the rate of production enters a terminal decline.
Why go nuclear?
Approximately 70% of energy in the US is produced from oil, coal and gas; nuclear power stations and renewable energy sources (hydro, solar, wind) produce only 16.4%. World population is growing as well as consumption of energy per person, but production of fossil fuels most likely will peak before 2050.
In 2005, the United States Department of Energy published a report (The Hirsch Report) saying that "The peaking of world oil production presents the U.S. and the world with an unprecedented risk management problem. As, liquid fuel prices and price volatility will increase dramatically, and, without timely mitigation, the economic, social, and political costs will be unprecedented. Viable mitigation options exist on both the supply and demand sides, but to have substantial impact, they must be initiated more than a decade in advance of peaking. …If alternatives are not forthcoming, the products produced with oil (including fertilizers, detergents, solvents, adhesives, and most plastics) would become scarce and expensive.
According to the report, in 2004 the average household spent $1,520 on fuel purchases for transport. In 2011 that expense climbed to $4,155. Rising oil prices will also affect the cost of food, heating, and electricity. With prices rising for these necessities, a high amount of stress will be put on current middle to low income families as economies contract from the decline in excess funds, decreasing employment rates. The US United States Department of Energy Report concludes that "without timely mitigation, world supply/demand balance will be achieved… Mitigation efforts will require substantial time; failure to initiate mitigation could be extremely damaging. A peak oil shock as outlined by Hirsch may have a much more severe outcome in the US compared to other parts of the world, especially Europe. In a world with a constantly growing population and with economic growth and prosperity directly linked with the use of finite fossil fuel resources, we must plan for alternative energy sources.
So, nuclear fission and possibly fusion can become a major source of energy in the 22 nd century Although the world's present measured resources of uranium (economically recoverable at a current price of 130 USD/kg) are enough to last for approximately 100 – 200 years at current consumption, vast amounts of uranium are contained in extremely dilute concentrations in seawater. Peak uranium can be in a very remote future. Introduction of breeder reactors will extend the mined uranium peak to 9,000 years, and combined with seawater uranium extraction, would make the uranium supply virtually inexhaustible: it has been estimated that there is up to five billion years' worth of uranium-238 for use in power plants. Breeders can also use thorium as a fuel, and thorium is more abandoned than uranium. Nuclear fusion can be a viable alternative to other sources of energy. There are approximately 33 grams of deuterium in every cubic meter of sea water – we have enough deuterium for millions of years. Reserves of easily mined lithium will last hundreds of years. If used to fuel a fusion power station, the lithium in one laptop battery would produce the same amount of electricity as burning 40 tons of coal. Tritium, another potential fuel for the fusion reactor, can be made of lithium using the high-energy neutron released from the fusion reaction.
PROS Low carbon dioxide (and other greenhouse gases) released into the atmosphere in power generation Low operating costs Known, developed technology ready for market (for fission reactors) Large power-generating capacity able to meet industrial and city needs (as opposed to low-power technologies like solar that cannot generate power for heavy manufacturing) Existing and future nuclear waste can be reduced through waste recycling, reprocessing and burning in breeders. CONS High construction costs due to complex radiation containment systems and procedures (~$2 billion) Long construction time (7 – 9 years) Accident risk; can be a target for terrorism Nuclear is a centralized power source requiring large infrastructure, investment, and coordination while decentralized sources (including solar and wind) can be less costly and more resilient The majority of known uranium around the world lies under land controlled by peoples who dont support it being mined from the earth Nuclear waste is hazardous and lasts for many years Pros and cons of nuclear energy
Matter (4.6% of the content of our Universe) was once considered to be made simply of atoms. Later it was discovered that atoms are made of elementary particles. Furthermore, it turned out that some elementary particles have a further fine structure and consist of quarks. For example, a proton consists of two u-quarks and one d-quark and a neutron consists of two d-quarks and one u-quark. Quarks and Leptons
Four fundamental interactions: gravity, electromagnetic, weak nuclear, strong nuclear Atomic number, atomic mass number: Isotopes:
Unstable isotopes exhibit radioactivity Alpha decay: Beta decay: Beta-plus decay: Electron Capture: Gamma decay: nucleus transition from excited state to the one with lesser energy (like the emission of a photon by an excited atom) (+ antineutrino ) (+ neutrino )
Decay Rate and Half-Life The rate ΔN/Δt at which the number of parent nuclei decreases: or which yields Half-life and decay constant λ: Half-life examples: 238 U ·10 9 years 14 C - 5,730 years 15 O seconds
Carbon Dating Carbon has three naturally occurring isotopes. Both C-12 and C-13 are stable, but C-14 decays by very weak beta decay to nitrogen-14 (see slide 14) with a half-life of approximately 5,730 years. Naturally occurring radiocarbon is produced as a secondary effect of cosmic- ray bombardment of the upper atmosphere: 1 n + 14 N 14 C + 1 p. Plants transpire to take in atmospheric carbon, which is the beginning of absorption of carbon into the food chain. Animals eat the plants and this action introduces carbon into their bodies. After the organism dies, carbon-14 continues to decay without being replaced. To measure the amount of radiocarbon left in a artifact, scientists compare the amount of C-14 is to the amount of C-12 (the stable form of carbon), to determine how much radiocarbon has decayed, thereby dating the artifact.
Nuclear binding energy is the energy required to split a nucleus of an atom into its component parts. The mass of a nucleus is always less than the sum of masses of the protons and neutrons after separation. Binding energy is a result of strong nuclear forces that hold the nucleus together. To overcome these forces we must supply binding energy = Δmc 2 (Δm is called mass defect). If reactants of lower average binding energy are changed into products of higher average binding energy, energy is released. For both nuclear fission and fusion the mass of nuclear reaction products are less than the mass of reactants. That is why when the products are formed, the energy conserved in mass is released. Energy Production: Nuclear Fission and Nuclear Fusion Mass–energy equivalence: the mass of a body is a measure of its energy content: E = mc 2 e + e + γ + γ Fusion: two atomic nuclei combine and form a heavier nucleus Fission: the breaking of a heavy nucleus into two (sometimes three) lighter nuclei
Nuclear Fission: Chain Reaction The chain reaction will continue if an least one neutron from U-235 fission strikes another nucleus and causes it to decay. The minimal mass for the reaction to sustain itself is called "critical mass. To increase the effectiveness of the chain reaction we can slow down the neutrons from fission with a moderator. It can reduce critical mass or provide chain reaction at lower concentrations of U-235. Example:
Control rods (to absorb neutrons; are used to adjust and control the level of reaction and therefore the level of power output): silver-indium-cadmium alloys or boron Moderators (to slow down neutrons and increase neutron efficiency): water or graphite Pressurized Nuclear Reactor
Natural uranium exists in a form of different minerals and on average contains % U- 234, 0.720% U-235, and % U-238. Only U-235 is used in light-water reactors. Uranium Conversion The primary uranium ore mineral is uraninite (UO 2 ). At a conversion plant, chemical processes convert it to uranium hexafluoride. The uranium hexafluoride is heated to become a gas and loaded into cylinders. When it cools, it condenses into a solid. After the uranium hexafluoride is enriched, a fuel fabricator converts it into uranium dioxide powder and presses the powder into fuel pellets. The fabricator loads the ceramic pellets into long tubes made of a noncorrosive material, usually a zirconium alloy. Once grouped together into a bundle, these tubes form a fuel assembly. Uranium Enrichment Uranium hexafluoride contains two types of uranium, U-238 and U-235. Since only U-235 can fission by thermal neutrons in current light-water reactors, natural uranium must be enriched to increase concentration of U-235. To make the uranium usable as a fuel, its U-235 content must be increased to 3% - 5%. Other thermally fissionable materials are U-233, Pu-239 and Pu-241. As U-235 is fissioned, some U-238 in the fuel rod is converted to Pu-239 extending the life of the fuel: U n U-239 Np-239 Pu-239. Nuclear Reactor Fuel Fuel assembly video:
Breeding Breeder reactors breed fissile fuel from U-238 and Th-232 and can extract almost all of the energy contained in uranium or thorium. They will require 100 times less fuel than traditional water reactors. Thorium-232 is about 3.5 times more common than uranium-238 in the Earth's crust. The breeders can significantly reduce the nuclear waste in particular by eliminating the long-term radioactivity from the spent fuel. The reason that the breeders are not used commercially yet is relatively high cost of reprocessing fuel safely.
Nuclear Waste Problem As of January 10, 2013 in 31 countries 438 nuclear power plant units with an installed electric net capacity of about 373 GW are in operation and 63 plants with an installed capacity of 61 GW are in 15 countries under construction. 56 countries operate a total of about 240 research reactors and a further 180 nuclear reactors power some 150 ships and submarines. Approximately 860 reactors are operating worldwide. A typical reactor will generate 20 to 30 tons of high-level nuclear waste annually. They produce approximately 22,000 tons of nuclear waste every year. These radioactive substances emit different type and energy of the ionizing radiation and have different chemical properties. Radioactive wastes comprise less than 1% of total industrial toxic wastes but certain radioactive elements in nuclear waste will remain hazardous to humans for hundreds or thousands of years, even for millions of years meaning they must be perfectly and reliably isolated for many centuries. World Nuclear Association
Classification of radioactive waste Low-level waste (Class A, B, C; short-lived, low-level) includes radioactively contaminated protective clothing, tools, filters, rags, medical tubes, and other items like that. Worldwide it comprises 90% of the volume but only 1% of the radioactivity of all radioactive waste. Usually it is buried in shallow landfill sites. Intermediate-level Waste contains higher amounts of radioactivity and may require special shielding. It includes some reactor components and contaminated materials from reactor decommissioning. Worldwide it makes up 7% of the volume and has 4% of the radioactivity of all radioactive waste. It may be solidified in concrete or bitumen for disposal. Generally short-lived waste (mainly from reactors) is buried, but long-lived waste (from reprocessing nuclear fuel) is disposed of deep underground. Low and medium level waste storage in South Africa High-level waste storage in Sweden at a depth of 420 m High-level Waste is the spent nuclear fuel of approximately 35 fission products after separation from the spent fuel by a chemical process. While only 3% of the volume of radioactive waste, it holds 95% of the radioactivity. It contains the highly-radioactive fission products and some heavy elements with long-lived radioactivity. It generates a considerable amount of heat and requires cooling, as well as special shielding during handling and transport. Currently more than 68,000 metric tons of waste are stored at commercial reactor sites, with about 2,000 metric tons added to the waste stockpile each year.
Used reactor fuel is temporarily stored at the nation's nuclear power plants in steel-lined, concrete pools or basins filled with water or in massive, airtight steel or concrete-and-steel canisters with heavy shielding and cooling. While stored, both the temperature and radioactivity of the wastes gradually decrease, simplifying their handling and disposal considerably. The U.S. Department of Energy will transport used nuclear fuel to the repository by rail and road, inside massive, sealed containers that have undergone safety and durability testing. to allow the short-lived radionuclides to decay to more-stable isotopes. After about five years of water storage, the heat output of the spent fuel is reduced to the extent that it can be safely stored in massive concrete containers that are air-cooled by convection. The ultimate disposal of High-level waste is deep in the ground in an engineered facility designed for safe containment and isolation of the material for thousands of years. Breeder Reactors can reduce high-level waste by breeding fissile plutonium-239 from furanium-238 and uranium-233 from thorium-232. Reprocessing of the nuclear fuel for breeders presents a proliferation concern since it produces weapons plutonium. FuelWaste Nuclear Reactor25 tons of uranium about 24 tons of uranium almost 1 ton of fission products 500 pounds of plutonium a small amount of other actinide elements Coal Plant3,000,000 tons of typical coal 7,000,000 tons of carbon dioxide 200,000 tons of ash 30,000 tons of sulfur oxide 10,000 tons of nitrogen oxide Compare yearly amounts of wastes produced by power plants of the same size (1,000 MWe), one burning coal and the other fueled by uranium (source: Center for Reactor Information) : High-level Waste
National Nuclear High-Level Waste Repository at Yucca Mountain in Nevada The Yucca Mountain Project originated from the 1982 Nuclear Waste Policy Act, to provide for the development of repositories for the disposal of high- level radioactive waste and spent nuclear fuel, to establish a program of research, development, and demonstration regarding the disposal of high-level radioactive waste and spent nuclear fuel, and for other purposes. After more than 20 years of scientific and engineering investigations, the Department of Energy submitted a license application to the Nuclear Regulatory Commission on June 3, 2008 for repository construction at Yucca Mountain. However, under the Obama Administration funding for development of Yucca Mountain waste site was terminated effective via amendment to the Department of Defense and Full-Year Continuing Appropriations Act, passed by Congress on April 14, This leaves United States civilians without any long term storage site for high-level radioactive waste, currently stored on-site at various nuclear facilities around the country, although the United States government can dispose of its waste at Waste Isolation Pilot Plant in New Mexico. in rooms 2,150 feet (660 m) underground. The Department of Energy is reviewing other options for a high-level waste repository. The Yucca Mountain Project
Three Mile Island, PA, USA March 28, 1979 In 1979 at Three Mile Island nuclear power plant in USA a cooling malfunction caused part of the core to melt in the # 2 reactor which was destroyed. Some radioactive gas was released a couple of days after the accident, but not enough to cause any dose above background levels to local residents. There were no injuries or adverse health effects The Worst Nuclear Disasters from the Three Mile Island accident. The partial meltdown of the Three Mile Island Unit 2 nuclear power plant was the most serious accident in the history of U.S. nuclear power plant operating history, despite the fact that it led to no deaths or injuries.
The Worst Nuclear Disasters Chernobyl, USSR April 26, 1986 The Chernobyl disaster is considered to have been the worst nuclear power plant accident in history. On the morning of April 26, 1986, reactor number four at the Chernobyl plant exploded. Two more explosions followed, and resulted fires sent radioactive cloud into the atmosphere. International Atomic Energy Agency reported that catastrophic accident was caused by severe violations of operating rules and regulations: "During preparation and testing of the turbine generator under run-down conditions using the auxiliary load, personnel disconnected a series of technical protection systems and breached the most important operational safety provisions for conducting a technical exercise. A 20,000-ton steel case called the New Safe Confinement, designed as a permanent containment structure for the whole plant, will be completed in firefighters had fought the fire for 5 hours and prevented if from spreading to the neighboring reactor #3. 3 volunteer divers drained the two bubbler pools under reactor preventing a huge thermal explosion and much bigger disaster. All men died soon after the accident and were buried in lead coffins, the lids soldered shut.
The Worst Nuclear Disasters Fukushima Daichi, March 11, 2011 An 8.9 magnitude earthquake and subsequent tsunami overwhelmed the cooling systems of an aging reactor along Japan's northeast coastline. The accident triggered explosions at several reactors at the complex, forcing a widespread evacuation in the area around the plant. Six workers have exceeded lifetime legal limits for radiation.
Global Warming Art Project
Nuclear Fusion Nuclear fusion occurs at very high temperatures (~10 7 K) because protons of hydrogen combine to helium only if they have enough speed to overcome their mutual Coulomb repulsion to get within range of the strong nuclear force (~ m). High density is also desirable for higher energy yield. These conditions are found in the stars, and the source Hydrogen Burning in the Sun The process of combining protons to form helium is an example of nuclear fusion. of the Sun's energy is nuclear fusion. Our Sun consumes 6.2·10 8 (620 million) tons of hydrogen into helium and emits 3.8·10 26 joules of energy every second.
In man-made fusion, the primary fuel is not constrained to be protons, so reactions with larger cross-sections can be chosen. Approximately 10 reactions using deuterium, tritium, helium, lithium and beryllium are suggested. Example reactions include: 17.6 MeV Man-made fusion
Fusion provides much more energy for a given mass of fuel than any technology currently in use including nuclear fission reactors. Since the fuel (primarily deuterium) exists abundantly in the ocean, fusion can potentially provide energy for the world for millions and millions of years. Fusion reactor will produce uninterrupted high power delivery with no greenhouse gases although scientists must overcome some technical and technological obstacle to design a commercial fusion power station. Two scenarios are being considered. There is one main challenge in the development of nuclear fusion for peaceful applications, that is, producing and containing hot dense plasma. There are two research approaches studying the problem, one is magnetic confinement and the other inertial confinement. Magnetic confinement uses magnetic and electric fields to heat and contain the plasma long enough for the fusion reaction to occur. Inertial confinement uses laser beams or ion beams to symmetrically apply a short pulse of energy to the surface of a thin sphere or pellet made of fusion fuel, causing the inner part of the target converge on the center of the sphere and produce high pressure and high temperature for reaction. Man-made fusion
Magnetic confinement Man-made fusion Tokamak design (first developed in the USSR in 1968 ) The idea is to keep the hot plasma out of contact with the walls of the container by keeping it moving in circular paths by means of the magnetic force acting on charged plasma particles. In December of 1993 the Tokamak Fusion Test Reactor (TFTR) in Princeton produced an output power level of 5.6 million watts in a controlled fusion reaction. While more power than this was required as input to the device, it represents significant progress in research. Construction of the International Thermonuclear Experimental Reactor facility began in 2008 and first plasma is expected in Its location is Cadarache in the south of France. This facility will build upon the understandings developed at the Princeton TFTR tokamak facility and other magnetic confinement research. The design goal is to produce 500 MW of output power for 50 MW of input power, or a tenfold yield. This reactor would then form the model for the construction of commercial power reactors.
Man-made fusion Inertial confinement The idea is to deliver energy to the outer layer of the deuterium-tritium target using high-energy laser beams. The heated outer layer explodes outward, producing a reaction force against the remainder of the target, accelerating it inwards, compressing and heating the fuel. The main problems with these devices have been: (a) low efficiency of lasers, (b) total energy delivery to the target is not enough, (b) required high symmetry of the target (the sphericity of the target must have extremely high precision, the aiming of the laser beams must be extremely precise, and the beams must arrive at the same time at all points on the target, (c) preventing premature heating of the fuel before maximum density must be achieved. Most advanced technology is implemented in recently built National Ignition Facility (NIF) in the United States at the Lawrence Livermore National Laboratory. In July 2012 the NIF laser system of 192 beams delivered more than 500 trillion watts (terawatts) of peak power and 1.85 megajoules of ultraviolet laser light to the target megajoules of energy is about 100 times what any other laser produces today. More information on NIF: https://lasers.llnl.gov
Addendum: some Chernobyl pictures
Chernobyl, April 26, 1986
Chernobyl, decontamination effort
Chernobyl Sarcophagus construction
Chernobyl The Sarcophagus, a 300,000 ton concrete structure, is finished
A ghost town
Workers have raised the first section of the New Safe Confinement, a colossal arch-shaped $2 billion structure that by 2015 will cover the exploded nuclear reactor at the Chernobyl power station. The shelter, shaped like a gargantuan Quonset hut, will be 257 meters by 150 meters (843 feet by 492 feet) when completed and at its apex will be higher than the Statue of Liberty. After that the reactor will be dismantled and radioactive waste will be removed. Chernobyl in 2013