Nuclear Energy Flashcards
How is energy conserved in alpha decay
Alpha particle recoils when the alpha is emitted so the energy released is shared between the two.
Energy is shared in inverse proportion to their masses
How is energy conserved in beta decay
Energy is shared in varying proportions between beta and neutrino
How is energy conserved in electron capture
Neutrino carry’s away the energy released
The atom also releases an X-ray photon when inner shell vacancy is filled by an electron
What is the binding energy of a nucleus
The work done to separate a nucleus into its constituent neutrons and protons
What is the mass defect if a nucleus
The difference between the mass of the separated nucleons and the mass of the nucleus
Binding energy in terms of mass defect
=(delta m)c^2
What does the binding energy per nucleon agains mass number A graph show
There is a peak binding energy per nucleon of about 8.5 MeV at A=45-55
Smaller Nuclei fuse to get to this stable state
Larger nuclei undergo fission to get to this state
What is induced nuclear fission
When a uranium235 isotope is bombarded with neutrons; it splits into two approximately equal fragments
Energy released in fission
The two fragments repel each other as they are both positively charged with sufficient force to overcome the SNF holding them together
They have a higher binding energy per nucleon than the original nucleus as they are more tightly bound together
Why does fusion happen
Two light nuclei combine together to gain a more tightly bound nucleus, this Means they have more binding energy per nucleon and are more stable
What is necessary with speed for fusion to happen
Only happens if the nuclei collide at high speed as they need to overcome the electro static repulsion between them and so they can interact between SNF
What is in the reactor core of a nuclear power station
Fuel rods spaced evenly, control rods and coolant
What do fuel rods consist of
Enriched uranium which is mostly U238 and 2-3% U235
Why are there control rods
They absorb neutrons
The depth of the control rods in the core is automatically adjusted to keep neutrons constant so that on average one fission neutron goes on to complete another fission event
What is a moderator used for
It slows the fission neutrons by repeated collisions with moderator atoms
High level radioactive waste disposal
Spent fuel rods are stored for up to a year in underwater cooling pods as they continue to release heat due to radioactive decay
Intermediate radioactive waste disposal
Radioactive material with low activity are stored in drums that are encased in concrete and stored in specifically constructed walls of reinforced concrete
Low level radioactive waste disposal
Lab equipment and protective clothing is sealed in metal drums and buried in large trenches
