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- There are many nuclear fuel cycles, depending upon the sort of reactor and the fuel utilized.
- It is also known as a nuclear chain reaction.
- The cycle comprises the front end, service period and back end.
- The front end is responsible for the generation of fuel.
- In the service phase, fuel prepared is used to generate electricity.
- The back-end phase is responsible for the disposal of waste.
- The nuclear fuel cycle depends upon the materials that can carry out the chain reaction with neutrons.
Read More: Atoms and Molecules
Key Terms: Nuclear. Fuel, Reactor, Atomic Power, Uranium, Energy, Open Fuel Cycle, Close Fuel Cycle, Kinetic Energy, Electricity
Types Of Nuclear Fuel Cycle
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Nuclear Fuel Cycle is defined as a series of industrial processes that starts from mining to the generation of electricity to finally reprocessing the waste material. The cycle is being carried out in nuclear reactors.
- Nuclear reactors make use of moderators to control the kinetic energy of the neutrons.
- The reactor is responsible for increasing the probability of nuclear fission.
- Graphite and heavy water are the most suitable examples of moderators.
The nuclear fuel cycle is divided into two categories, namely, the Open (or once-through) fuel cycle (without reuse of nuclear materials) and the Closed fuel cycle (with reuse of nuclear materials taken out from irradiated fuel).
Nuclear Fuel Cycle
Open Fuel Cycle
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The open fuel cycle is a cycle where the utilized fuel is not changed for reuse, and nuclear material only passes through the reactor once.
- It is also known as once through fuel cycle.
- Then, at that point, the fuel is shipped off away from reactor capacity and wanted to be moulded.
- Later, it is placed into the last store of the process.
- Various atomic power nations endorse this fuel cycle technique.
- The concept is used for pressurized heavy water reactors (PHWR) and graphite-moderated light water-cooled reactors (RBMK).
Read More: Energy Level Diagram
Closed Fuel Cycle
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The closed fuel cycle is used to separate the leftover uranium and plutonium after an adequate cooling period from the splitting items and different actinides.
- This technique is mainly used in light water reactors (LWR).
- It is in the form of mixed oxide fuel as the reprocessed uranium and plutonium are then re-utilized in the reactors.
- Apart from the ongoing LWR reusing process, another closed fuel cycle practice is reusing nuclear materials in quick reactors.
- Here, reprocessed uranium and plutonium are used to produce fast reactor fuel.
- In this case, a reactor can deliver more plutonium than it consumes.
Also Check: Nuclei
Stages of the Nuclear Fuel Cycle
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Nuclear Fuel Cycle is divided into two parts, namely, the front-end and the back-end. The front end of the cycle consists of the mining, milling, processing, enrichment, and nuclear fuel fabrication process. On the other hand, the back end of the nuclear fuel cycle consists of the generation of electricity, temporary storage of nuclear material, reprocessing, and recycling of material.
The stages of the nuclear fuel cycle are as follows:
Front End of the Nuclear Fuel Cycle
The processes involved in the front-end are as follows:
Uranium ore investigation
The process related to the uranium ores for uranium production during the finding and development.
Uranium ore mining
It involves the extraction of uranium ore from the ground. The process involves oxygenated groundwater circulated through an orebody's pores to soften uranium oxide and bring it to the surface. The convention mill is used to restore uranium oxide from a solution.
Uranium ore processing
It is the process of the milling and refining of the ore to produce uranium concentrates, including in-situ leaching (commonly called yellow cake — ammonium diuranate containing 80 to 90% of U3O8)
Conversion
It includes the conversion of uranium oxide into uranium hexafluoride. The 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.
Enhancement
The isotopic enrichment of UF6 is done to obtain the enriched 235U concentration. 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 carried through two processes: low-enriched uranium and depleted uranium.
Uranium fuel fabrication
It is related to the production of nuclear fuel to be injected into the nuclear reactor. In this process, uranium dioxide is converted into pellet form.
- The pellets are fired at a very high temperature to form enriched uranium.
- It will then undergo a grinding process.
- These pellets are connected through metal tubes organized in a fuel assembly to assure consistency in the fuel.
The Front End
Back End of the Nuclear Fuel Cycle
The processes involved in the back end are as follows:
At-reactor (AR) used Fuel Storage
It is the method used to store the used fuel in reactor-used fuel storage facilities (wet type) for a temporary period.
Away from the reactor (AFR) used Fuel Storage
It is the method that relates to the storage of used fuel storage facilities (wet or dry type) temporarily.
Fuel Reprocessing and Recycling
The method is related to the treatment of used fuel so that it can extract the usable materials and recycle them in the reactor.
Fuel Conditioning:
It includes fuel packages that are suitable for handling, transport, storage, and/or disposal.
Disposal of used Fuel
The method related to positioning used fuel/wastes in a suitable facility without the purpose of recovery.
The Back End
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Things To Remember
- Nuclear fuel cycle is the set of measures and operations needed to produce nuclear fuel.
- The two fuel cycles involved in the process are open fuel cycle and closed fuel cycles.
- ‘Open’ (or once-through) fuel cycle is without reuse of nuclear materials.
- ‘Closed’ fuel cycle with reuse of nuclear materials taken out from irradiated fuel.
- Nuclear fuel cycles depend upon the sort of reactor and the fuel utilized.
- The nuclear fuel cycle is divided into two phases: the front-end and the back end.
Sample Questions
Ques. What are the four initial phases of the fuel cycle? (2 Marks)
Ans. Four initial phases of the fuel cycle are named as:
- Uranium production
- Conversion
- Enrichment
- Fuel fabrication
Ques. What are some uses of a nuclear power plant? (2 Marks)
Ans. Nuclear power plants can be used for the generation of electricity. These plants help in marine nuclear propulsion. The atomic fission heat is transferred to a working fluid, including gas or water. This further runs through the steam turbines. This can switch the shafts of an electrical generator or even propel a ship.
Ques. Mention some benefits of using nuclear power? (2 Marks)
Ans. Nuclear power stations have a very reliable base energy fee. This means that the energy that is generated is renewable. It works alongside other sources of electricity, including solar and wind. The production of electricity can be reduced or enhanced. This depends on the electricity demand.
Ques. Which fuel is used in nuclear power plants? (3 Marks)
Ans. Uranium-235 is employed as a fuel in various concentrations. Some reactors, for example, the CANDU reactor, can use natural uranium in combination with uranium-235 concentrations of only 0.7 %, whereas other reactors need uranium in slightly higher concentrations (3 % - 5 %).
- Plutonium – 235 (Option B) and Plutonium – 238 (Option C) are the non-fissile isotopes of Plutonium.
- Similarly, uranium – 238 (Option D) is also a non-fissile isotope of uranium.
- Therefore, the fuel used in nuclear power plants is the fissile isotope of uranium, i.e. Uranium – 235.
Ques. Who is responsible for the invention of nuclear power? (2 Marks)
Ans. The person who is primarily responsible for the invention of nuclear power is Enrico Fermi. He was a prominent figure in nuclear energy exploration. He was born in Rome, Italy, and was the first physicist and scientist to break an atom.
- He continued to work in the domain and was responsible for further developing nuclear power.
- Enrico Fermi and Leo Szilard are also credited for discovering the first nuclear reactor responsible for creating a series of triggered reactions in a nuclear chain.
Ques. Explain uranium fuel fabrication. (2 Marks)
Ans. Uranium fuel fabrication is the process related to the production of nuclear fuel to be injected into the nuclear reactor. 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.
Ques. What is Nuclear Energy? (3 Marks)
Ans. In alpha and beta decay, energy gets released in the way of the kinetic energy of the daughter nuclide and radioactive emission. Primarily, nuclear energy is derived from the loss of mass during nuclear reactions.
- Two nuclear reactions give out an enormous quantity of energy.
- They are nuclear fission and nuclear fusion reactions.
- A nuclear reaction is a process where two nuclei or nuclei of an atom and a subatomic particle from outside the atom collide.
Ques. Is Uranium-238 a good nuclear fuel? (3 Marks)
Ans. Uranium-238 is the most common isotope of uranium in nature, which constitutes 99.28% of natural uranium. With a probability of about 0.00055%, Uranium-238 decays by spontaneous fission.
- Uranium-238 is fissionable but not fissile.
- Fissionable means that an element undergoes fission after capturing a neutron of high or low energy, whereas fissile means that a fissionable nuclide can be induced to undergo fission with low-energy thermal neutrons.
- Therefore, Uranium-238 is a good nuclear fuel.
Ques. What is the open fuel cycle? (2 Marks)
Ans. In the open fuel cycle, the utilized fuel is not changed for reuse, and nuclear material only passes through the reactor once. Then, at that point, the fuel is shipped off away from reactor capacity and wanted to be moulded and placed into the last store in this method of activity.
Ques. Which produces more energy, nuclear fusion or nuclear fission? (1 Mark)
Ans. Nuclear fusion produces more energy than nuclear fission because lighter elements like hydrogen are involved in nuclear fusion, whereas in nuclear fission, heavier elements like uranium are involved.
Ques. What steps are involved in the back end of the nuclear fuel cycle? (2 marks)
Ans. The steps involved in the back end are as follows:
- At-reactor (AR) used fuel storage
- Away from the reactor (AFR) used fuel storage
- Used fuel reprocessing and recycling
- Used fuel conditioning
- Disposal of used fuel
Ques. Give two suitable examples of moderators used in nuclear reactors? (1 mark)
Ans. The two suitable examples of moderators used in nuclear reactors are graphite and heavy water.
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