What is nuclear fission?
Splitting of an atomic nucleus into two smaller nuclei
What does fission process results in the emission of?
- Two or three high-speed neutrons
- energy - in forms of gamma radiation and kinetic energy of the nuclei and neutrons
Naturally occuring uranium is mostly?
Uranium-238 which which is non-fissionable
What do most nuclear reactors use?
'Enriched' uranium that contains 2-3%
uranium -235 which is fissionable
some reactors use plutonium-239
What is induced fission?
Occurs when a neutron absorbed by uranium-235 nucleus or plutonium-239 nucleus and nucleus splits
What is spontaneous fission?
Occurs without a neutron being absorbed
When does a chain reaction occur?
When neutrons released from each fission event
causes further fission events to occur
What is the result of nuclear reactor being controlled?
One fission neutron per fission, on average, goes on to produce further fission
What is function of control rods in nuclear reactor core?
Absorbs surplus neutrons
the depth of rods in the core is adjusted to maintain a steady chain reactions
How is moderator used in nuclear reactor?
Fast neutrons don't cause further fission so in reactor core
moderator used to slow high-speed neutrons