Nuclear hazards I-Air pollution:
Front end[ edit ] Waste from the front end of the nuclear fuel cycle is usually alpha-emitting waste from the extraction of uranium. It often contains radium and its decay products.
Uranium dioxide UO2 concentrate from mining is a thousand or so times as radioactive as the granite used in buildings.
It is refined from yellowcake U3O8then converted to uranium hexafluoride gas UF6. As a gas, it undergoes enrichment to increase the U content from 0. It is then turned into a hard ceramic oxide UO2 for assembly as reactor fuel elements.
It is stored, either as UF6 or as U3O8. Some is used in applications where its extremely high density makes it valuable such as anti-tank shellsand on at least one occasion even a sailboat keel. These isotopes are formed in nuclear reactors.
It is important to distinguish the processing of uranium to make fuel from the reprocessing of used fuel. Used fuel contains the highly radioactive products of fission see high level waste below.
Many of these are neutron absorbers, called neutron poisons in this context. These eventually build up to a level where they absorb so many neutrons that the chain reaction stops, even with the control rods completely removed.
At that point the fuel has to be replaced in the reactor with fresh fuel, even though there is still a substantial quantity of uranium and plutonium present. In the United States, this used fuel is usually "stored", while in other countries such as Russia, the United Kingdom, France, Japan and India, the fuel is reprocessed to remove the fission products, and the fuel can then be re-used.
While these countries reprocess the fuel carrying out single plutonium cycles, India is the only country known to be planning multiple plutonium recycling schemes.
Long-lived fission product Activity of U for three fuel types. In the case of MOX, the U increases for the first thousand years as it is produced by decay of Np which was created in the reactor by absorption of neutrons by U Total activity for three fuel types.
In region 1 we have radiation from short-lived nuclides, and in region 2 from Sr and Cs On the far right we see the decay of Np and U The use of different fuels in nuclear reactors results in different spent nuclear fuel SNF composition, with varying activity curves.
Long-lived radioactive waste from the back end of the fuel cycle is especially relevant when designing a complete waste management plan for SNF. When looking at long-term radioactive decaythe actinides in the SNF have a significant influence due to their characteristically long half-lives.
Depending on what a nuclear reactor is fueled with, the actinide composition in the SNF will be different. An example of this effect is the use of nuclear fuels with thorium. Th is a fertile material that can undergo a neutron capture reaction and two beta minus decays, resulting in the production of fissile U The SNF of a cycle with thorium will contain U Its radioactive decay will strongly influence the long-term activity curve of the SNF around a million years.
A comparison of the activity associated to U for three different SNF types can be seen in the figure on the top right.
This has an effect in the total activity curve of the three fuel types. The initial absence of U and its daughter products in the MOX fuel results in a lower activity in region 3 of the figure on the bottom right, whereas for RGPu and WGPu the curve is maintained higher due to the presence of U that has not fully decayed.Introduction to Chemical Reactions and Equations The space shuttle—and any other rocket-based system—uses chemical reactions to propel itself into space and maneuver itself when it gets into orbit.
Radioactive contamination, also called radiological contamination, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids or gases (including the human body), where their presence is unintended or undesirable (from the International Atomic Energy Agency - IAEA - .
Nuclear Proliferation Nuclear missiles, nuclear bombs, nuclear wars, everything seems to have fallen into the same category, but nobody has really payed attention to the “big picture” and has actually took the time to realize what this is really about. Safeguards to Prevent Nuclear Proliferation.
Most countries participate in international initiatives designed to limit the proliferation of nuclear weapons. The international safeguards system has since successfully prevented the diversion of fissile materials into weapons.
Its scope has been widened to address undeclared nuclear activities. Whatever one’s views about nuclear power, well-focused research leads to better understanding of problems and innovative solutions, helping to reduce the risks and costs of industrial activities.
Industrial processes In The Essential Chemical Industry - Online, there are 76 units which describe key aspects of the chemical industry in a concise way. They are designed so that you can ‘dip in’ to them to retrieve the information you need.