- Fast-neutron reactor - Wikipedia
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- Russia Will Test a New Sodium Fast Reactor and Reprocessing to Handle All Nuclear Waste
Closing the fuel cycle means all of the waste is converted back into usable fuel. AEM-Technology started the manufacture of the reactor pressure vessel for MBIR in March, and has said that construction of the demonstration reactor should be completed by The project is expected to cost The MBIR will be the most powerful research reactor in the world.
Nuclear waste is mostly even-numbered Uranium isotopes. Uranium can be converted to plutonium for fuel. A thermal neutron is a free neutron with a kinetic energy of about 0. A fast neutron is a free neutron with and 1 Megaelectron volt with a speed over 14, km per second. Enriched uranium gets the uranium from 0.
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Highly enriched goes higher. The uranium and the Plutonium can be used in fast neutron reactors and new molten salt nuclear reactors and they can generate energy. The Uranium in a fast reactor has about the same energy as Uranium in most of the current reactors. The Russians have operated fast reactors commercially for decades. The French ran a fast reactor for a while as well. China is building some.
There are several companies making molten salt nuclear reactors. There was a 10 megawatt thermal molten salt reactor operated in the s. These reactors are not as useful for generating nuclear bombs. Molten salt reactors can use up almost all of the uranium and plutonium. If you use the neutrons in the right way or use advanced chemistry the uranium and plutonium in what is called nuclear waste can be used as nuclear fuel. Processing used fuel is the same as processing the concentrate of any metal mineral to recover the valued metals contained in it.
There are advanced chemistry facilities for recycling the fuel. This is called reprocessing. There are several ways to do it and they are expensive. It is done mainly in France. The uranium that we use for all of our nuclear plants is about 65, tons per year.
The word uses 7. We use over , times more coal for 4 times as much power. The coal is burned and puts three times as much CO2 into the air. The burning adds two oxygens to the carbon. Fossil energy sources C coal, oil and natural gas C are the most readily available, but they raise concerns about global climate change and other forms of environmental pollution. Over the past decade, nuclear plants have improved their operational reliability, safety records, and economic competitiveness, and nuclear energy is now recognized as the only power technology that can generate large amounts of electricity without producing greenhouse gases and other atmospheric pollutants.
It is the technology of choice to meet the ever-expanding demand for electrical energy. Even with reprocessing, as is done in Europe and Japan, such reactors can utilize little more than one percent of the total energy potentially available from the mined uranium. The U. The unused energy is discarded as tailings in the enrichment process or as spent-fuel A waste. On the other hand, fast-spectrum reactors can utilize essentially all of the uranium resources through recycling and breeding, when called for in the future , making nuclear energy resources comparable to all fossil energy sources combined.
Uranium resources. To explore the uranium resources issue, let us look at the potential scenario for nuclear energy expansion that is depicted in Figure 2. This is a conservative assumption, to illustrate the resource implications. The current total world-wide nuclear capacity is GWe.
We assume that life-extension of current reactors and GWe of new LWRs will be the second-generation providers of nuclear energy. It is widely believed that there is a lot of cheap uranium, but this is illusory. Most utilities have long-term uranium supply contracts. When there are gaps in these long-term contracts, small quantities are purchased in the spot market. At present five hundred tonnes of highly enriched uranium from excess Russian weapons material are being blended down, flooding the uranium spot market. Figure 3 powerpoint or pdf file shows that, with the AFR introduced, the uranium requirements can be capped well below the A estimated additional resources category, which is, in effect, the limit of uranium resources that could be economically recovered to feed a fuel cycle based on thermal reactors.
Fast-neutron reactor - Wikipedia
But if we continue with that type of reactor, the uranium requirements rise even beyond the A speculative resources category, which consists of uranium that is thought to exist mostly on the basis of indirect evidence and geological extrapolations. As the term implies, the existence, size, and recovery cost of such resources are guesses.
There is also a great deal of uranium in sea water, but it is so dilute that it is economically out of reach for use in the very inefficient thermal reactors.
Those tests showed that even most the severe accident-initiating events would not lead to reactor damage or release of radioactive material. In one test, we shut off the power to the pumps that circulate coolant through the core, and in the other we cut off all active heat removal. In both tests the reactor safely shut itself down without human or mechanical intervention. In any other type of reactor, either of these occurrences would initiate a reactor-disabling accident.
Sodium coolant. Because sodium has a very high boiling temperature, the cooling system can operate at essentially atmospheric pressure. Sodium is also non-corrosive to structural materials used in the reactor. These unique characteristics of a sodium-cooled system result in superior reliability, operability, maintainability, and long lifetime, all of which contribute to low life-cycle costs.
A A pool type of cooling configuration.
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The AFR core sits in a large pool of liquid sodium, combining high thermal inertia with convective removal of decay heat in the event of loss of forced coolant flow. Most of the previous fast-reactor designs used a cooling A loop, which does not have those safety advantages. Metal fuel, rather than oxide.
This is a major safety advantage. In all reactors there is a A Doppler reactivity effect, which causes the reactivity to increase if the temperature rises. In the AFR, as a result, there is only a small temperature rise upon loss of coolant, limiting the Doppler reactivity rise.
The fact that the fuel is metallic is what makes it practical to use pyrometallurgical processing A pyroprocessing for short, discussed next. The most innovative feature of the AFR is pyroprocessing, which promises revolutionary improvements in waste management, nonproliferation characteristics, and economics. With oxide fuel, reprocessing is done by the PUREX process, which produces chemically pure plutonium.
Pyroprocessing not only does not do that, it cannot. Figure 4 powerpoint or pdf file is a simplified pyroprocessing flow sheet. The key element of pyroprocessing is electrorefining. Spent fuel rods chopped into small pieces are loaded into the anode basket. One type of cathode recovers uranium and the other one recovers all other actinide elements together: Pu, Np, Am, Cm, and also some U. The anode basket, which retains the cladding hulls and noble-metal fission products, is melted to produce high-level waste in metallic form.
Russia Will Test a New Sodium Fast Reactor and Reprocessing to Handle All Nuclear Waste
The electrolyte salts, containing most of the fission products, are passed through zeolite columns where the fission products are immobilized by incorporation into the zeolite molecular structure through ion exchange and occlusion. The zeolite powder is then mixed with glass frits and melted at high temperature to form a stable ceramic waste form called sodalite.
Originally developed for the IFR, pyroprocessing works with metallic fuel.
http://cars.cleantechnica.com/sombra-contra-las-armadas-de-la-oscuridad-1.php The radioactive isotopes in spent fuel are of two types: fission products and actinides. The fission products as a group have an effective half-life of about thirty years.