fission and fusion Flashcards
what is fusion?
when two small nuclei join together to produce a larger nucleus, this resutlts in a loss of mass from the smaller nuclei and a release of energy
where does fusion happen?
in starts, but reactors can be made artificially
what is fission?
when one large nucleus splits into two smaller nuclei
where does fission happen?
nuclear power stations
how does fission happen?
- a neutron is absorbed by the U-235 nucleus to make U-236
- it is unstable and splits by nuclear fission after
why is a neutron absorbed in fission?
it makes the nuclei more unstable so it can decay and creates energy
what are the product of fission?
the nucleus splits in two smaller nuclei and two or three neutrons
- gamma rays are also emitted
energy
- its transferred from the nuclear potential energy to kinetic energy and it can be converted into electrical energy
what is a chain reaction?
when the new neutrons from the product of the first fission reaction creates another fission reaction, and it repeats
what factors need to be controlled in fission?
the number of free neutrons in the reactor
and the energy of the free neutrons
what do reactors contain that help to control things?
- moderators
- control rods
what is the purpose of a control rod?
to absorb neutrons
- they are made of a material. that absorbs neutrons without becoming unstable itself
what does lowering the rods do?
decreases the rate of fission as more neutrons are absorbed and vice versa
what is the purpose of a moderator?
to slow down neutrons
how do moderators work?
it surround the fuel rod and control rods
- -the neutrons slow by colliding with the molecules of the moderators
- they then flow so that they are in thermal equilibrium with the moderator
what is the role of shielding?
- its a steel and concrete walls, almost 2 meters thick
ensures that the environment around the reactor is safe
it also absorbs hazardous radiation
