Critical fission energy question

In summary, the conversation discusses the determination of fissility and the possibility of fission at different neutron energies. It also mentions the comparison of binding energy and critical energy in determining fissility. The calculation of mass-energy difference is also mentioned.
  • #1
andybham
15
0
I have a fission exam next week, can someone help me with this past paper question:

If you know the masses of two nuclei (A)Z and (A+1)Z, (say masses are (A) and (A+1)) and you know the 'critical fission energy' of (A+1)Z, how do you determine if (A)Z is fissile? if it is not fissile, at what neutron energy would you expect fission to be possible.
 
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  • #2
How about comparing the binding energy of the compound nucleus (A+1)Z with the critical energy?
 
  • #3
is this done by calculating the separation energy? E = m(n) + m(A) - m(A+1)
 
  • #4
http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucbin.html

E = (m(n) + m(A) - m(A+1)) c2
yes - it is the mass-energy difference between the reactants and product(s). The energy is released as prompt gamma or as the kinetic energy if there are two or more products.

Calculate the mass-energy difference between U235+n and U236.
 

What is critical fission energy?

Critical fission energy is the minimum amount of energy needed to initiate a self-sustaining nuclear fission chain reaction. This energy is required to overcome the binding energy of the nucleus and cause it to split, releasing more energy and neutrons that can then cause other nuclei to split.

How is critical fission energy calculated?

The calculation of critical fission energy involves considering the mass of the fissile material, the number of neutrons produced per fission, and the probability of those neutrons causing additional fissions. These factors are used to determine the critical mass and critical fission energy of the material.

Why is critical fission energy important?

Critical fission energy is important because it is necessary for a nuclear reactor to sustain a chain reaction and produce energy. If the critical fission energy is not reached, the reaction will not continue and no energy will be generated. It is also important to understand and control critical fission energy in order to prevent accidents and ensure the safe operation of nuclear reactors.

How is critical fission energy related to nuclear weapons?

In order for a nuclear weapon to function, a critical fission energy must be achieved in a very short amount of time. This is typically done by compressing a critical mass of fissile material with high explosives, causing a rapid and intense chain reaction. Understanding critical fission energy is crucial for the development and maintenance of nuclear weapons.

Can critical fission energy be controlled?

Yes, critical fission energy can be controlled through various means, such as adjusting the amount and type of fissile material, moderating the speed of neutrons, and controlling the rate of fission reactions. This control is necessary for the safe and efficient operation of nuclear reactors and weapons.

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