IP2.31.4 Nuclear fission

© Oxford University Press 2011

Nuclear fission

IP2.31.4 Nuclear fission

© Oxford University Press 2011

Nuclear fission is the splitting of an atomic nucleus. Currently all nuclear reactors work by nuclear fission. Either uranium 235 or plutonium 239 nuclei are split into two smaller nuclei. The process generates heat energy which is used in the same way as a

conventional thermal power station. The heat is used to produce steam which turns turbines, which then turn generators.

The products of fission are usually radioactive. Radioactive waste is one of the major drawbacks of fission reactors.

IP2.31.4 Nuclear fission

© Oxford University Press 2011

Most reactors use uranium 235. The uranium nucleus absorbs a neutron

and then splits into two smaller nuclei and releases 2 or 3 more neutrons.

These neutrons are then absorbed by other uranium nuclei causing them to split.

This process continues and is called a chain reaction. This is because the reaction is self-sustaining – the neutrons from one reaction cause another reaction to take place forming a link or chain between the reactions.