Reactor Theory Flashcards
Reactor theory -
What is nuclear stability
Ability if an atom to resist change.
It is affected by the neutron to proton ratio.
What is binding energy
The amount of energy required to separate an atom
Equivalent to mass defect
What is binding energy per nucleon
Average amount of energy to remove a nucleon
What is mass defect
Mass of individual parts of atom is greater than mass of whole atom. This is because energy is released during atom formation.
What are 4 fundamental forces in order of strength
1) strong force
2) electromagnetic force
3) weak force
4) gravitational force
What is fissile material
Material that can fission solely due to neutron energy (thermal neutron) U235 is Fissile
All fissile material is fissionable, but not all fissionable material is fissile
What is fissionable material
Material that can undergo fission but requires additional energy in the form of neutron kinetic energy
U238 can fission but it requires a fast neutron
Critical energy
The amount of energy required for fission to occur
Describe strong force
Strongest of natural forces
Acts on nucleons (protons and neutrons) and binds them together. It’s range is quite small (size of nucleus)
Describe electromagnetic force
Force that acts between charged particles either to repel or attract. This force extends over and infinite range and is cumulative.
Mass defect
When an atom is formed energy is released.
E=Mc’2
Mass of atom combined is less than mass of it’s parts. Because energy is released during formation
Binding energy
Energy required to split an atom
Binding energy and mass defect are equivalent
What is the standard notation of an atom
What are coulomb and nuclear forces
Coulomb force is when two charged particles with the same charge slightly separated experience repulsion
Nuclear forces of attraction are produced when adjacent nucleons are involved
What is the mass-energy equivalence
E=mc^2 E= energy released MeV m=mass (AMU) c=speed of light (m/sec) 931.5(MeV/AMU)
What is the macroscopic cross section
It represents the interaction probability per unit length of the neutron’s travel.
What is the mean free path
The average distance that the neutron would travel through the material before undergoing an interaction
What is Uranium’s atomic number and how many protons and neutrons does it have
Uranium is U with atomic number of 92
It has 92 proton and 146 neutrons U 238
Atomic mass is 238.02891
Fission Product equilibrium
When new nuclei are being created in an operating reactor it is possible for the concentration of a nuclide to build in to eventually reach equilibrium. Since the production rate is a constant (at a constant power level) the concentration merely has to increase until the total decay rate (λN) is equal to the production rate.
We essentially reach equilibrium in 5-7 half lives
Fission Energy
The various processes that accompany fission result in liberation of energy - U235 produces approximately 200MeV
83% - initial kinetic energy fission fragments
6% - initial kinetic from neutron and gamma ray released
7% - delayed release of gamma rays and beta particles (decay heat)
5% - is lost in the form of neutrinos
What is a prompt neutron
Prompt neutron is a neutron born before 10^-14 seconds - neutron from initial fission
Prompt neutrons make up most neutrons but require more collisions to become a thermal neutron.
What is a delayed neutron
Delayed neutron is neutron born after 10^-14 seconds. Born from secondary fission reaction.
There are less in core but they require less collisions to become thermal neutrons.
What is K eff
K eff is the #neutrons from fission in one generation / # neutrons in previous generation
Fast fission factor
Fast neutrons produced by ALL fission events/ fast neutrons produced by THERMAL fission evet
