What is the Nuclear Fuel Cycle?
Nuclear Fuel Cycle is an array of industrial processes which includes the production of electricity from uranium in nuclear reactors. It can be defined as various activities that are related to generating electricity from nuclear reactions.
The nuclear fuel cycle also termed a nuclear chain reaction, comprises a front end, service period and back end. The front end consists of steps that are necessary for the preparation of the fuel, the service period involves steps in which fuel is utilized during the time span of a nuclear reactor, and the back end comprises steps that are essential for managing, conversion or disposal of used fuels.
If used fuel is not converted for reuse, then the process is defined as an open fuel cycle. If used fuel is converted for reuse, then the process is described as a closed fuel cycle. Let’s consider uranium. It is placed in a reactor for an average of three years to generate electricity. Once the electricity is produced, used fuel further undergoes various steps that are mentioned above.
Uranium
Uranium is found in rocks, rivers, seawater and in most solids. It is one most slightly radioactive metals. In most places in the world, the concentration of this metal is adequately high in the ground. They are extracted and used as nuclear fuel.
Uranium Mining
Two methods are used to recover uranium ore, evacuation and situ techniques. Evacuation may be open pit mining. The Situ process involves oxygenated groundwater that is circulated through the pores of an orebody to soften uranium oxide and bring it to the surface. The convention mill is used to restore uranium oxide from a solution.
Uranium Milling
It is carried out near the site of a uranium mine. A majority of mining facilities involve a mill; wherein a single mill can process ores from several mines. Milling involves the production of uranium oxide concentration that is carried out from the mill.
Conversion of Uranium
It includes the conversion of uranium oxide into uranium hexafluoride. This product only consists of natural uranium, not the enriched product. Uranium hexafluoride is converted into a gaseous form at a moderate temperature of 57 °C.
Enrichment
The concentration of U-235 is less than a requirement to sustain a nuclear chain reaction. Hence it has to be enriched in fissionable isotopes and it is carried through two processes namely low-enriched uranium and simply depleted uranium.
Fabrication
In this process, uranium dioxide is converted into pellet form. The pellets are fired at a very high temperature to form enriched uranium and then undergo a grinding process. These pellets are connected through metal tubes organized in a fuel assembly to assure consistency in the fuel.
Power Generation
The core of a reactor is made up of several hundreds of fuel assemblies. U – 235 isotopes split, producing an excess of heat. This process is known as a chain reaction, and it entirely depends upon the type of moderator, namely graphite or water.
Used Fuels
In some countries depending upon the policies, used fuels may be shipped into central storage facilities.
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