radiation Flashcards
What is alpha radiation made up of
two protons and two neutrons (a helium nucleus)
characteristics of alpha radiation
-strongly ionising
-slow moving
-weakly penetrating (stopped by paper)
-positively charged
what is beta minus radiation
a high energy electron
what is beta plus radiation
high energy positron
beta minus characteristics
-mildly ionising
-fast moving
-stopped by a few mm of aluminium
-negatively charged
what is gamma radiation
a form of EM radiation
characteristics of gamma radiation
-weakly ionising
-travels at the speed of light
-strongly penetrating (stopped by lead)
-chargeless
what is radioactive decay
the decay of a substances nuclei, this decay is completely random and unpredictable
what is activity (A)
the number of nuclei that decayer second, measured in Bq
what is half life
time it takes for the number of radioactive nuclei to halve
what is the decay constant (λ)
probability of a decay occurring in a unit time
nuclear fission
splitting of a large nucleus, by absorbing a slow moving neutron, and producing two smaller nuclei, several neutrons and energy
thermal neutron
slow moving so can be absorbed
spontaneous fission
is rare, a fissile nuclei usually needs to absorb a thermal neutron to induce fission
chain reactions
neutrons produced in a reaction go on to induce further fission reactions
critical mass
minimum amount of a fissile substance needed to maintain a steady flow of fission reactions
roll of control rods
to absorb neutrons to prevent further fission reactions (the further in the rods the more neutrons that can be absorbed)
roll of the moderator
slows down neutrons to reach thermal speeds to be absorbed
roll of fuel rods
consists of fissile material, each rod contains less than the critical mass in horde for collisions to remain controlled
roll of coolants
carries a way thermal energy produced by fissile reactions to generate steam and turn generators for electrical energy
how do you cool nuclear waste
cooled in cooling ponds to reduce its temp to safe levels
where should high level waste be stored
in thick steel containers underground
nuclear fusion
fusing two smaller nuclei to form a single large nuclei and produce large quantities of energy
which elements are usually used for fusion
tritium and deuterium
conditions for nuclear fusion
-very high temp
-very high pressure
which produces more energy
fusion
what is binding energy
energy required to split up the nucleus into its individual nucleus. it is the energy equivalent to the mass deficit.
does a greater binding energy mean a more stable nucleus
yes
what is mass defect
the difference between the mass of the nucleus and the mass of its individual components
why are high temperatures required for nuclear fusion
to provide kinetic energy so that nuclei have sufficient energy to overcome the repulsive forces
why are high pressures required for fusion
so that nuclei can get close enough to maintain collision rate to maintain fusion, close enough to form a strong force
