Nuclear Fission

what is nuclear fission?

the breaking up of atomic nuclei

what is the process of nuclear fission

• a slow-moving neutron is absorbed by an atom of uranium-235

• the uranium-235 becomes uranium-236, an unstable isotope

• The uranium splits into two daughter nuclei and three neutrons

• This is known as nuclear fission

• Each of the three neutrons can be absorbed ny another atom of uranium-235

• Each of these uranium atoms undergoes fission, releasing even more neutrons

• This is known as a chain reaction

what is the equation for fission?

235^_92U + 1^_0n -> 236^_92U -> 141^_56Ba + 92^_36K + 3 1^_0n

what controls are in place to make nuclear fission safer?

• Control rods

  • made of boron

  • absorbs unwanted neutrons

  • prevent out of control reactions

• Moderator

  • water commonly used

  • slows down neutron so it can be absorbed

  • keeps chain reaction going

• Fuel rods - contain enriched uranium-235 or plutonium-239

what are the pros and cons of nuclear fission

Pros	Cons
Doesn’t contribute to global warming High-tech research required benefits other industries Low fuel quantity reduces mining and transportation effects on environment Power station has long lifetime Produce no polluting gas	Cost of building and safely decommissioning are very high Cannot react quickly to changes in electricity demand Waste is radioactive and safe disposal is difficult and expensive More energy released than in chemical processes (bombs) Radiation leaks cause disasters (Chernobyl)