Nuclear reactions as a source of energy
3 marks · NormalDescribe how a chain reaction is produced in a nuclear reactor using uranium-235.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
A chain reaction occurs when neutrons produced by fission go on to cause further fission reactions in other uranium-235 nuclei, and this repeats.
Also accept: Each fission produces more neutrons, which trigger more fission events.
Common mistakes: Not mentioning the role of neutrons in propagating the reaction
Show mark scheme and worked solution
Marking points
B1 · 1 mark · Mentions that fission produces more neutrons.
B1 · 1 mark · Explains that these neutrons go on to cause more fission.
B1 · 1 mark · Describes this process as repeating, forming a chain reaction.
Worked solution
In uranium-235, when a nucleus absorbs a neutron and undergoes fission, it produces additional neutrons. These neutrons can then strike other uranium-235 nuclei, causing further fission reactions. As this continues, one fission leads to more, resulting in a chain reaction.