Nuclear fission Flashcards
Define nuclear fission
Splitting of an atoms nucleus into two smaller daughter nuclei and release of two or 3 neutrons and energy. There’s is a little mass conversion into energy.
What is the product of nuclear fission
two or three neutrons at high speed (fisssion neutrons)
energy in form of gamma em radiation and kinetic energy in fragment nuclei and fission neutrons.
How do chain reactions occur?
The fission neutrons cause fissions in other nuclei to split and this repeats maintaining the chain reaction.
Induced fission formula for u235 example
92-U-235 + 0-n-1 ==> 92-U-236==> A+B+ 3 0-n-1
What is spontaneous fission?
Fission that happens naturally
What method is used to increase amount and porportion of u-235?
Enrichement
Why do we do it?
In natural uranium u-238 exist 99% which is non fissionable. However, uranium when enriched has 2-3% uranium.
What happens to u-238 in a reactor?
It doesn’t undergo fission but it changes into anothe rheavy nuclei called plutonium used in another reactor .
What is nuclear reactor made up of and explain use?
Control rods- its depth adjusted to keep chain reaction under control
Moderator- normally water to slow down the fission neutron as fast neutrons dont cause further fission of u-235.
Fuel rods- The water coolant to go and come back from heat exchanger outside core to turn turbines.
Pressuriser to pressurise the steam
Step to step inside nuclear core reactor:
Fission occurs in fuel rod
The water coolant is heated due to thermal energy released.
The Water becomes pressurised steam
Steam turns turbine and generates power
Steam condenses and returns back to core.
Disadvantages of Nuclear energy
Radioactive waste
High start and maintenance cost
Risk of a disaster
Negative public view
Non-renewab;e
How is radioactive waste stored?
In deep underground or pool of water.
What do thick wall vessels and concrete walls do?
Withstand high temp and pressure and absorb ionising radiation.
