Nuclear reactions

 

Nuclear reactions

Summary

All the energy we call clean, dirty, or renewable, comes from natural nuclear reactions of some sort.

All nuclear energy produced by man, comes from the fission, or splitting, of uranium by slow neutrons.   Nuclear produces energy with very little carbon footprint.. However only 0.65% of the uranium is used, leaving the rest as radioactive waste that needs to be stored for hundreds of thousands of years. The slow neutron process was most likely chosen chosen because in this waste is plutonium that can be used for bombs.

      

          Slow neutron reaction                                          Fast neutron reaction

It would have been better if the alternative reaction using fast neutrons had been chosen. This process uses 99.5% of the fuel, and the waste is shorter lived, hundreds of years, not hundreds of thousands of years. It would use thorium and uraniumm 238, of which there is a lot more than uranium 235. No fast reactor has produced power commercially. It may be too late now as it would take 30 years or so to get the process going and we have only 10-20 years to go zero carbon.

Nuclear fusion has been researched for 60 years or so and is not yet able to produce power. Even if it worked it may have a problem. For each tonne of deuterium used, 3.5 tonnes of lithium will be used. And it will be destroyed completely. It may be more useful as batteries.

 

 

Radioactive decay  - Alpha decay

Introduction to nuclear reactions

Chemical reactions involve changes to the arrangement of electrons around the nucleus.

Nuclear reactions are any reaction where the nucleus of an atom changes. In this process energy is either given off or taken in.

Nuclear reactions include.

Radioactive decay. Alpha particles, comprising two protons, and two neutrons, are given off spontaneously.  This can be detected on a radio, so is termed radioactive. It is responsible for the heating of granite rocks producing geothermal energy. Space craft on long journeys are powered by heat generated this way.

Nuclear fusion . Under great pressure, light nuclei are fused together to form heavier nuclei. Any reaction producing a nucleus up to the size of iron, gives off  heat. In a supernova explosion, energy is absorbed in fusing heavier nuclei together to form elements heavier than iron.  (more details)

Nuclear fission   When heavy nuclei such as uranium are made unstable by the addition of an extra neutron, the atom becomes unstable and spilt. this gives off energy. (more details).

Big bang. This gave all the stars, planets, and moons their movement. Tidal power harnesses energy from the moons movement.

All the energy we use comes from nuclear reactions.