Chapter 5 Nuclear energy Flashcards
5A:
Define the term “mass defect.”
The mass defect refers to the difference in mass between a nucleus and all of its nucleons. The sum of the masses of all individual nucleons will be greater than the mass of the nucleus as a whole.
5A:
Define “nuclear fusion.”
Nuclear Fusion is the process of fusing (forcing) two smaller nuclei together to form one larger nucleus.
5A:
Define “nuclear fission.”
Nuclear fission is the process of larger nuclei being split into several smaller nuclei due to an input of a neutron, which reduces the stability of the nucleus as neutrons need to exist in higher states of energy.
5A:
Define the term “binding energy.”
The “binding energy,” of a nucleus is the energy required to split a nuclei into its constituent nucleons.
5A:
Explain what a binding energy curve shows.
The “binding energy curve,” shows the binding energy of nuclei against the number of nucleons within the nucleus. Binding energy peaks Nickel 62, anything to the left of Nickel-62 will undergo Fusion to obtain a greater quantity of Binding energy, whereas anything to the right of Nickel-62 will undergo Fission to obtain a greater quantity of Binding energy.
5B:
Define the term “fissile.”
Something which is “Fissile,” is capable of sustaining Fission chain reactions. So, a fissile mass contains Fissile material.
5B:
Define the “Neutron multiplication factor.”
At a given point in time, this is the average number of neutrons from Fission reactions (occurring within a Fissile mass) which will cause further Fission reactions to occur.
5B:
Define “Criticality.”
When a Fissile Mass is in a critical state, it means that the number of Fission reactions occurring remains constant. Hence, the Neutron multiplication factor equates to 1.
5B:
Define “Sub criticality.”
When a Fissile mass is in a sub-critical state it means the number of Fission reactions occurring is decreasing. Hence, the neutron multiplication factor is less than 1.
5B:
Define “Super criticality.”
When a Fissile mass is in a super-critical state, it means the number of Fission reactions occurring is increasing. Hence, the neutron multiplication factor is greater than 1.
5B:
Outline how the mass of a Fissile mass impacts its criticality.
The greater the mass, the higher the chance that neutrons released from Fission reactions will be captured by the Fissile material and cause further Fission reactions, instead of escaping the Fissile mass. Thus, as Mass increases the Neutron multiplication factor increases as well, and the same vice versa.
5B:
Outline how the shape of a Fissile mass impacts its criticality.
The greater the surface area for a given Fissile mass, there is higher the chance neutrons will escape the mass and not be captured by the Fissile material. Hence, a greater surface area yields a lower neutron multiplication factor, and the same applies vice versa.
5B:
Define “neutron absorption.”
This is the process of a non-Fissile material absorbing neutrons and not undergoing a Fission reaction as a result.
5B:
Explain the purpose of a control rod.
A control rod is a non-fissile material inserted into a Fissile mass to control Fission chain reactions by absorbing neutrons.
5B:
Define “neutron moderation.”
This is the process of reducing the speed (kinetic energy) of neutrons from Fission reactions in a Fissile material.
Hence, neutron moderators are placed all over a Fissile material to cause collisions with these neutrons and decrease their speed.
