Mining And Processing Nuclear Fuels
Uranium is one of the least plentiful mineralsmaking up only two parts per million in the earth’s crustbut because of its radioactivity it is a plentiful supply of energy. One pound of uranium has as much energy as three million pounds of coal.
Radioactive elements gradually decay, losing their radioactivity. The time it takes to lose half of its radioactivity is called a “half life.” U-238, the most common form of uranium, has a half life of 4.5 billion years.
Uranium is found in a number of geological formations, as well as sea water. To be mined as a fuel, however, it must be sufficiently concentrated, making up at least one hundred parts per million of the rock it is in.
In the U.S., uranium is mined from sandstone deposits in the same regions as coal. Wyoming and the Four Corners region produce most U.S. uranium.
The mining process is similar to coal mining, with both open pit and underground mines. It produces similar environmental impacts, with the added hazard that uranium mine tailings are radioactive. Groundwater can be polluted not only from the heavy metals present in mine waste, but also from the traces of radioactive uranium still left in the waste. Half of the people employed by the uranium mining industry work on cleaning up the mines after use.
The pellets are then packed into 12-foot long rods, called fuel rods. The rods are bundled together into fuel assemblies, ready to be used in the core of a reactor.
Comparison With Renewable Energy
Slowing global warming requires a transition to a low-carbon economy, mainly by burning far less fossil fuel. Limiting global warming to 1.5 °C is technically possible if no new fossil fuel power plants are built from 2019. This has generated considerable interest and dispute in determining the best path forward to rapidly replace fossil-based fuels in the global energy mix, with intense academic debate. Sometimes the IEA says that countries without nuclear should develop it as well as their renewable power.
World total primary energy supply of 162,494 TWh by fuels in 2017 :6,8
Several studies suggest that it might be theoretically possible to cover a majority of world energy generation with new renewable sources.The Intergovernmental Panel on Climate Change has said that if governments were supportive, renewable energy supply could account for close to 80% of the world’s energy use by 2050.While in developed nations the economically feasible geography for new hydropower is lacking, with every geographically suitable area largely already exploited, some proponents of wind and solar energy claim these resources alone could eliminate the need for nuclear power.
Speed of transition and investment needed
The Case Against Nuclear Power
The major problem is the perceived dangers associated with disposal of waste – for example it could be that uranium must be stored for thousands of years for the radiation to reach safe background levels . This, plus the constant danger that radioactive material could leak into soil or into water supplies means for some, the perceived benefits are vastly outweighed by the risks. Even with all the safety checks in the world, people make errors and the slightest error could be very costly indeed. By now, everybody knows what happened at Chernobyl, Three Mile Island and most recently – Fukushima.
Critics also say that it can take decades to put an effective nuclear program into action . In which time, with greener technology always under development, it could fall behind or become obsolete by the time of completion. With a portion of the initial nuclear power plants closing or requiring significant upgrade after just a few decades , it seems that the life cycle of some plants is much shorter than perhaps the outward cost might warrant .
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Mining Enrichment And Disposal Of Uranium
Uranium is a metal that can be found in rocks all over the world. Uranium has several naturally occurring isotopes, which are forms of an element differing in mass and physical properties but with the same chemical properties. Uranium has two primordial isotopes: uranium-238 and uranium-235. Uranium-238 makes up the majority of the uranium in the world but cannot produce a fission chain reaction, while uranium-235 can be used to produce energy by fission but constitutes less than 1 per cent of the worlds uranium.
To make natural uranium more likely to undergo fission, it is necessary to increase the amount of uranium-235 in a given sample through a process called uranium enrichment. Once the uranium is enriched, it can be used effectively as nuclear fuel in power plants for three to five years, after which it is still radioactive and has to be disposed of following stringent guidelines to protect people and the environment. Used fuel, also referred to as spent fuel, can also be recycled into other types of fuel for use as new fuel in special nuclear power plants.
What is the Nuclear Fuel Cycle?
The nuclear fuel cycle is an industrial process involving various steps to produce electricity from uranium in nuclear power reactors. The cycle starts with the mining of uranium and ends with the disposal of nuclear waste.
Oklo: A Natural Nuclear Reactor
Modern deposits of uranium contain only up to ~0.7% 235U , which is not enough to sustain a chain reaction moderated by ordinary water. But 235U has a much shorter half-life than 238U , so in the distant past the percentage of 235U was much higher. About two billion years ago, a water-saturated uranium deposit underwent a naturally occurring chain reaction that was moderated by groundwater and, presumably, controlled by the negative void coefficient as the water boiled from the heat of the reaction. Uranium from the Oklo mine is about 50% depleted compared to other locations: it is only about 0.3% to 0.7% 235U and the ore contains traces of stable daughters of long-decayed fission products.
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Vant Physics Of Nuclear Reactors
Series: Nuclear reactor physics
The series comprises the materials highlighting the following problems: – Theory and methods of calculations related to nuclear reactors, blankets of thermonuclear reactors, radiation protection, radiation transport. – Problems of numerical and experimental studies of the codes implemented for PC: description and abstracts of the codes and programming complexes and systems. – Numerical studies related to physics of nuclear reactors, blankets of thermonuclear reactors, radiation protection, radiation transport studies of certain aspects of nuclear energy development. – Experimental methods and experimental studies related to nuclear reactors and to the mentioned above associated spheres. – Mathematical problems of transport and reactor theory.
Chief Editor: Doctor of Physics and Maths V.F. KolesovPeriodicity: 3 times a year.
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Atomic And Nuclear Physics
Knowledge of atomic and nuclear physics is essential to nuclear engineers who deal with nuclear reactors. It should be noted that atomic and nuclear physics is a very extensive branch of science. Nuclear reactor physics belongs to applied physics, drawing from particle physics or nuclear chemistry. These branches have common fundamentals. Atomic and nuclear physics describe fundamental particles , structure, properties, and behavior. These physical fundamentals consist of:
See also: Interaction of Radiation with Matter
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Thermohydraulics Of Nuclear Core
Heat removal from nuclear reactors is also a key issue of reactor physics. For a reactor to operate in a steady state, with an internal power distribution that is independent of time, all of the heat released in the system must be removed as fast as it is produced. This is accomplished by passing a coolant through the core and other regions where heat is generated.
The thermohydraulics deals with thermal behavior and the nuclear cores hydraulic behavior . The nature and operation of this coolant system are some of the most important considerations in designing a nuclear reactor. In the PWR reactors, some phenomena must be avoided. Namely, DNB and coolant saturation are very dangerous phenomena.
Brief History Of Nuclear Power
Research into the possibility of harnessing nuclear power began in the 20th century when it was discovered between the end of the 19th century and the middle of the 20th century that radioactive elements released an enormous amount of energy . It wasn’t long after development of atomic weapons that governments saw other benefits and potential of nuclear power. Though dwindling fossil fuels were not an issue in the 1950’s when the first commercial nuclear power stations opened around the world, it was clear there was a potential for efficient generation of cleaner power that could easily accommodate the growing demands of the future. Just 1kg of uranium, for example, produces the same energy as 2000 metric tonnes of coal . Not only that, but that release of additional neutrons could release even greater amounts of energy . World War II ended and so began the nuclear race alongside the Cold War – the two issues tied inextricably to developing weapons with greater power, and to provide even greater energy needs in east and west.
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Examples Of Nuclear Fission
In the next section, let us study what nuclear energy is.
Eddington And Stellar Nuclear Fusion
Around 1920, Arthur Eddington anticipated the discovery and mechanism of nuclear fusion processes in stars, in his paper The Internal Constitution of the Stars. At that time, the source of stellar energy was a complete mystery Eddington correctly speculated that the source was fusion of hydrogen into helium, liberating enormous energy according to Einstein’s equation E = mc2. This was a particularly remarkable development since at that time fusion and thermonuclear energy, and even that stars are largely composed of hydrogen , had not yet been discovered.
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The Physics Of Nuclear Reactors
Most existing nuclear power plants are pressurized water reactors, in which water is used both to carry heat away from the reactor core and as the moderator to allow the chain reaction to take place. The water is prevented from boiling by a pressurizer that maintains the pressure somewhat above saturation so that the water remains liquid. The core, enclosed in a steel pressure vessel, consists of low-enrichment uranium-oxide pellets made up into rods clad in zirconium alloy, which in turn are grouped into fuel assemblies.
Connected to the vessel are several loops, each of which takes the primary hot water to a generator, in which steam is produced by boiling secondary water. The loop then returns the primary water to the pressure vessel. A reactor building, known as the nuclear island, encloses the vessel and its surrounding pipe work and safety systems. Equipment outside the island, such as steam turbine-generators, is largely the same as for any fossil-fuelled station.
The above description is of a thermal reactor, so-called because the moderator allows neutrons to slow to thermal energies to cause fission. However, in fast reactors, like the gas-cooled fast reactor and the sodium-cooled fast reactor , the neutrons are not slowed and so could destroy long-lived waste mixed in fuel through the process of transmutation. Fast reactors also generate energy from a larger proportion of the uranium than thermal reactors.
What Is Nuclear Physics
Nuclear physics is a scientific discipline that studies the structure of nuclei, their formation and stability. It mainly focuses on understanding the fundamental nuclear forces in nature and the complex interactions between neutrons and protons.
Nuclear Physics is defined as the branch of physics deals with the structure of the atomic nucleus and its interactions.
Experimental nuclear physics drives innovation in scientific instrumentation. Todays research in nuclear physics is enabling a range of new technologies in materials science chemistry, medicine, and biology. The application of nuclear physics lies largely in the field of power generation using nuclear energy. Once the force holding the nucleus was understood, we started splitting and fusing neutrons. The process of splitting the nucleus to generate energy is known as Nuclear Fission and the process of fusing two neutrons to generate energy is known as Nuclear Fusion.
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Nuclear Power Construction Starts And First Grid Connections 2007
Only 4.8 GW of construction was launched in 2020, with three reactors in China and one in Turkey. The 58 GW of nuclear capacity under construction were primarily in non-OECD economies , China and Russia . The two OECD economies with the most capacity under construction are Korea and the United Kingdom . Out of the 20.8 GW of capacity under construction in the rest of the world, the leading economies are India and the United Arab Emirates .
Construction in the United Arab Emirates is progressing according to schedule, with the first unit commissioned in 2020. In OECD countries, Hinkley Point C is the largest ongoing new-build project and the first project for the United Kingdom since 1995. The Covid19 pandemic had some impact on this large infrastructure project, however, and the first unit will now be commissioned in June 2026 instead of late 2025.
Other new-build projects are in the preparation phase in Argentina, Brazil, Bulgaria, the Czech Republic, Egypt, France, Finland, Hungary, India, Kazakhstan, Poland, Saudi Arabia and Uzbekistan. These are typically large reactor projects and, judging from current policies and ongoing projects, could amount to new additions of ~55 GW.
Non-OECD economies lead new nuclear construction globally
Nuclear Physics At Service For Other Fields
NP is a research field with lot of connections with other fields. Therefore, the grand challenges for them reflect on grand challenges for NP. We list below what we believe are the most relevant ones.
Neutrino physics: Neutrinos remain among the most intriguing particles of the Standard Model. They are not massless, but their mass is extremely small, they are the only particles which interact only through the weak force, making their detection a great challenge for experimentalists. In fact, we even do not know the ultimate nature of neutrinos. It is natural that they are the object of intense research. Many accelerator experiments are running, or planned to run, with the ultimate goal of measuring neutrino-oscillation parameters, as the neutrino mass hierarchy and the charge-conjugation parity violating phase. These experiments employ nuclear targets, like 16O, 56Fe, 208Pb, or 40Ar, and simple models for the nucleus and reaction mechanism. A grand challenge of NP is to provide an accurate determination of the neutrino-nucleus cross section in a wide energy range, to become accurate inputs for the analysis of experimental data.
The study of the nuclear reactions involved in stellar evolution, both in non-explosive and explosive environments, is also fundamental to understand how stars live and eventually die. The grand challenges mentioned in section 2 regarding nuclear structure and nuclear reactions find their application also in this field.
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The Problems With Nuclear Energy
Nuclear energy isnt all good news, though. The Fukushima Nuclear Disaster is the latest testament to that. This disaster was a consequence of the combination of a tsunami and a powerful earthquake in March 2011. Although the chain fissile reactions were shut down automatically in response to the earthquake, the tsunami damaged generators responsible for cooling the reactors of the plant. Without cooling, the components of the core of the reactors can literally melt from all the energy released from these reactions. In this case, they did. Radioactive material was subsequently released along with several chemical explosions, which were initiated by the immense heat released by the nuclear reactions.
Why is radioactive material dangerous? To start with, to be radioactive refers to the fact that this material is actively emitting radiation. This is not the same kind of radiation were familiar with such as visible electromagnetic radiation from a light bulb. Electromagnetic radiation emitted as a result of nuclear fission, known as gamma rays, has 100,000 times more energy than visible light. Radioactive material can also emit highly energetic electrons and small clusters of protons and neutrons . This concentrated energy causes the molecules in our body to react in ways that can be extremely damaging, sometimes giving rise to cancer.
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