NUCLEAR Flashcards
Nuclear decay equation
Activity = (decay constant) (number of nuclei left)
A = λN
λ = probability of a nucleus dealing in the next second
Metastable states
Nuclei have specific energy levels. Some can remain excited for long periods of time after decay, producing pure gamma emitter
Decay Chain
Unstable nuclei decay several times and can take different routes to end up at the same stable nucleus
Binding energy
nucleus splits into constituent nucleons and gain mass, the work required is called BINDING ENERGY
Why does the total binding energy increase when a nuclear event occurs?
nucleons become more stable, the total mass decreases, energy released, total binding energy increased
When nuclei split apart in nuclear events, rather than turning into other nuclei that are more stable it’s…
mass is turned into energy
Temperature needed for fusion
high, in order for particles to overcome the electrostatic repulsion and bring them to within range of strong force
Nuclear fission reactor (process)
induce fission by bombarding U235 with neutrons. Becoming U235 which is unstable, undergoes fission producing two daughter nuclei and more neutrons.
Nuclear fission reactor: fuel rods
Contain Uranium nuclei that undergo fission when absorb neutron
Nuclear fission reactor: control rods
Absorb neutrons without further fission occurring (creating boron)
Nuclear fission reactor: moderator
Slows down neutron to ‘thermal’ speeds so they are able to be absorbed by uranium nuclei in another rod.
(made from graphite or water)
Increases rate of fission
Nuclear fission reactor: coolant
special liquid/gas (heavy water, CO2) takes KE to water to make steam to turn turbine.
Nuclear waste
Fission fragments still in fuel rods (radioactive and hot). left to cool in ponds, then vitrified in molten glass that is non porous. Stored deep underground to minimise radiation exposure
