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Nuclear Fission

Nuclear fission is the phenomenon in which an atomic nucleus splits into lighter nuclei. This reaction can be spontaneous in some isotopes, but usually is the result of heavy nuclei absorbing a neutron. Because fission often results in the emission of multiple neutrons, this reaction can be self-sustaining, making such things like nuclear reactors and nuclear weapons possible.

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Is moderation of neutrons always used to slow nuclear fission?

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Asked by Wiki User

No, moderation of neutrons is not always used to slow nuclear fission. In some types of nuclear reactors, such as fast breeder reactors, fast neutrons are intentionally not moderated to slow down the fission process. These reactors operate using fast neutrons to sustain a chain reaction. However, in most commercial nuclear reactors, moderation of neutrons is employed to slow down the fission process and maintain a controlled chain reaction.

What is correct for a nuclear fission reaction?

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Asked by Wiki User

In a nuclear fission reaction, the nucleus of an atom is split into two smaller nuclei. This process releases a large amount of energy and typically involves the use of a neutron to initiate the reaction. The resulting smaller nuclei and additional neutrons can then go on to potentially initiate further fission reactions.

What happens to fuel rods that are used to create nuclear fission?

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Asked by Wiki User

You have a misapprehension there, it is uranium oxide that is used in fuel rods, not fossil fuel

Compare and contrast fusion and fission?

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Asked by Wiki User

With nuclear fission, a large atomic nucleus (such as a uranium nucleus) breaks apart into smaller nuclei, and energy is released. With nuclear fusion, small atomic nuclei (such as hydrogen) join to become larger nuclei, and energy is released. Fusion of hydrogen releases much more energy than any other type of either fusion or fission. Note that the dividing line between heavy nuclei and light nuclei is the iron nucleus, which is at the perfect point of nuclear stability, so that neither fusion nor fission of iron nuclei would release any energy.

What is the basic principle of the steam turbine that can be used to drive generator to produce electricity?

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Asked by Wiki User

A gas turbine extracts energy from a flow of hot gas produced by combustion of gas or fuel oil in a stream of compressed air. It has an upstream air compressor (radial or axial flow) mechanically coupled to a downstream turbine and a combustion chamber in between. "Gas turbine" may also refer to just the turbine element. Energy is released when compressed air is mixed with fuel and ignited in the combustor. The resulting gases are directed over the turbine's blades, spinning the turbine, and mechanically powering the compressor. Finally, the gases are passed through a nozzle, generating additional thrust by accelerating the hot exhaust gases by expansion back to atmospheric pressure. Energy is extracted in the form of shaft power, compressed air and thrust, in any combination, and used to power aircraft, trains, ships, electrical generators, and even tanks. A gas turbineextracts energy from a flow of hot gas produced by combustion of gas or fuel oil in a stream of compressed air. It has an upstream air compressor (radial or axial flow) mechanically coupled to a downstream turbine and a combustion chamber in between. "Gas turbine" may also refer to just the turbine element. Energy is released when compressed air is mixed with fuel and ignited in the combustor. The resulting gases are directed over the turbine's blades, spinning the turbine, and mechanically powering the compressor. Finally, the gases are passed through a nozzle, generating additional thrust by accelerating the hot exhaust gases by expansion back to atmospheric pressure. Energy is extracted in the form of shaft power, compressed air and thrust, in any combination, and used to power aircraft, trains, ships, electrical generators, and even tanks.

What is the chemical makeup of radioactive waste derived from nuclear fission?

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Asked by Mackfan

The most active and dangerous part is the spent fuel itself, because it contains very active fission products. Less active arisings come from contaminants in the reactor primary system water circuit (crud). The least active category will be clothing and cleaning materials which have been used in slightly contaminated areas of the plant.

What are examples of fission?

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Asked by Wiki User

Example 1If a 235U atom splits up into two nuclides with mass number 117 and 118, estimate the energy released in the process.

SolutionA search of stable nuclides with mass numbers 117 and 118 are 117Sn50, and 118Sn50, their masses being 116.902956 and 117.901609 amu respectively. The mass of 235U is 235.043924 amu. The difference in mass 235.043924 - (116.902956 + 117.901609)

= 0.2394 amu (931.5 MeV) / (1 amu)

= 223 MeV.

Discussion

Actually, the fission is induced by neutrons, and usually the split is uneven. In reality, two neutrons are also released, but they were ignored in this example to make the estimate simple. Furthermore, the fission products are beta emitters as illustrated by example 2.

Example 2Assume the neutron induced fission reaction to be, 235U + n ® 142Cs55 + 90Rb35 + 4 n.

explain the results and estimate the energy released.

Solution

The neutron-rich fission products are beta emitters:142Cs55 ( , b) 142Ba56 ( , b) 142La57 ( , b) 142Ce58 ( , b) 142Pr59 ( , b) 142Nd60 (stable)

90Rb37 ( , b) 90Sr38 ( , b) 90Y39 ( , b) 90Zr40 (stable)

The masses of n, 142Nd60 and 90Zr40 are 1.008665, 141.907719 and 89.904703 amu respectively. The energy per fission and the decay energy are estimated as follows. Energy = 235.04924 - (89.904703 + 141.907719 + 3 x 1.008665)

= 0.210823 amu (931.5 MeV / amu)

= 196 MeV (1.6022e-13 J / MeV)

= 3.15e-11 J

Fission and fusion of nuclear power plant?

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Asked by Wiki User

Fission is the splitting of an atom, fusion is the joining of 2 atoms into one. In most fission, neutrons are bomabarded at the nucleus of uranium or plutonium and this causes a ripple effect of more neutons being released from the fuel. The process generates large amounts of heat which is either used for destruction or steam engines. Fusion most often occurs with 2 Hydrogens being fused together to form helium. Deuterium (Hydrogen with a neutron and proton instead of just a proton) and tritium (one proton and two neutrons) are high energy atoms that are used in testing nuclear fusion. Our star (the sun) is based, like most stars, on Hydrogen being fused to generate heat and Helium.

Does Nuclear fission as used in nuclear power plants produces radioactive waste with long half lives?

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Asked by Wiki User

yes, Nuclear fission as used in nuclear power plants produces radioactive waste with long half lives. However, this creates no problems. This wastes are either confined in the spent nuclear fuel (that is stored either in wet storage or in dry storage facilities) or stored as vitrified nuclear waste.

What are the economic impacts of uranium nuclear fission?

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Asked by Wiki User

The nuclear energy obtained from uranium or plutonium is the most important alternative to fossil fuels. Oil and methane will be exhausted in less than 100 years. Wind, geothermal, solar, organic wastes etc. are useful but not serious alternative for 10 billions inhabitants.

How nucleas of nuclear weapon fission?

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Asked by Wiki User

A Uranium or Plutonium nucleus fissions (whether in bomb or reactor) by capturing a neutron and entering an unstable excited state. This excited state releases its excess energy a couple nanoseconds later by splitting into two pieces, one about 1/3 and the other about 2/3 the mass of the original nucleus, and 2 or 3 neutrons.

What are the three main components of a fission reactor?

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Asked by Wiki User

  1. fuel
  2. moderator
  3. cooling system
  4. control rods
  5. SCRAM system

Why do chain reactions happen in nuclear fission?

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Asked by Wiki User

When a slow neutron is captured by a nucleus of U235 or Pu239, the nucleus fissions or splits into two fission fragments and on average 2.5 neutrons are released as well as the energy which we use as heat. In the reactor, some of these are absorbed by the moderator, some escape from the core at the boundaries, but if just one of them is then captured by another nucleus, the process is self repeating, it goes on at a steady rate which can be described as a chain reaction, a type of endless chain. For the reaction to continue at a steady rate, the number of neutrons buzzing about in the core must be constant, this is called the neutron flux, so many neutrons per sq cm per second. The fine control of neutron absorption is done by control rods of absorbing material, usually boron steel alloy, and these are adjusted so that the flux is constant, giving constant power. Note that the reaction is self starting due to the fact that U235 and Pu239 give off a small number of spontaneously produced neutrons, this happens whatever the state of the reactor and continues when it is fully shutdown, so as soon as the control rods are withdrawn the neutron flux starts to increase. You don't have to ignite the fuel to start, as you do with fossil fuels.

Why nuclear fission take high temperature for a raection?

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Asked by Wiki User

Not at all, the temperature of U-235 or Pu-239 which are used for nuclear energy production by fission, has no effect on the fission reaction, which is driven only by the capture cross-section for neutron capture. Slow neutrons are captured more strongly than fast ones, so it is an advantage for the moderator not to be at a high temperature.

What happens to an atom when nuclear fission occurs?

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Asked by Wiki User

It breaks into two parts, which are the nuclei of two lighter elements. The total number of protons remains the same, so the two resulting nuclei are of two elements with a total atomic number equal to that of uranium, ie 92. The actual elements formed are not the same in every fission, there is a range of different ones formed. Plotting a graph of the yield against atomic number you get two broad peaks, as shown in the article linked below. The electrons in the uranium atom are distributed between the two products depending on their atomic numbers (ie number of protons). The number of neutrons in the products don't add up because some neutrons are released in the fission and become separate from the resulting nuclei, in fact this is how the chain reaction is sustained.

If For a sustainable fission reaction each fission must produce exactly how many additional fission reaction(s).?

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Asked by Wiki User

To sustain a fission chain reaction, each fission reaction must result in one more fission reaction. And that one should result in one more, and so on.

What kind of energy is given off from a nuclear fusion reaction and from a nuclear fission reaction?

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Asked by Wiki User

the "disappearance" of a small amount of mass. Most of the energy from nuclear fusion of deuterium and tritium, which is the most likely reaction to be harnessed by man, is given off as kinetic energy of the neutrons formed. This is one of the problems involved-how to make use of this energy, even when the plasma can be contained and made to fuse, which has only been achieved for brief bursts so far. The neutrons will have to be stopped in some material surrounding the plasma to produce heat, but what material will stand up to these conditions is not clear.

In nuclear fission most of the energy appears first as kinetic energy of the fission fragments, which are then stopped in the fuel resulting in heat being generated which can be removed by the coolant, water or gas. There is also some gamma ray energy released.

Were is nuclear fission used in the world?

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Asked by Wiki User

Many countries have nuclear reactors: United States, United Kingdom, Russia, China, France, Japan, India, Canada, Romania, Bulgaria, Hungary, etc.

What Equation involves nuclear fission and nuclear fusion?

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Asked by Wiki User

Involving fission & fusion at the same time? These reactions are completely different from each other and have no physical or mathematical relationships. I suppose you could claim that a hydrogen bomb that uses a fission trigger is an example of such an equation, however, the fission occurs before the fusion, so they are still separate and distinct from each other. The mass-energy equivalence equation, E=mc^2, is used to calculate the energy released due to the missing masses found in the fission or fusion calculations, but it comes at the end to convert the mass result into energy only.