Loading…
Loading…
GCSE Physics · key term
A sequence of fission reactions in which neutrons released by one fission cause further nuclei to split.
Used by AQA, Edexcel and OCR
Specification 4.4.4.1 · Paper 1
Revise: Nuclear fissionIf one is absorbed by a suitable nucleus, it may cause that nucleus to split and release still more neutrons. Those neutrons may then cause further fissions. This repeating, branching sequence is a chain reaction.
Specification 6.40P · Paper 1
A continuing process in which neutrons released by nuclear fission cause further nuclei to undergo fission.
For a chain reaction, arrows should show released neutrons travelling to other unstable nuclei and causing further fissions. The number of fission events should increase through successive stages.
When comparing a reactor with a nuclear weapon, state whether the chain reaction is controlled or uncontrolled and link this to the rate of energy release.
Do not say that control rods absorb all neutrons during normal operation. Enough neutrons must remain to sustain a steady chain reaction.
Create a free account to read GCSE Physics revision notes for your exam board and track your progress.
Some of these neutrons may cause further fissions, producing a chain reaction.
Specification P6.2d · Paper 2 (Foundation), Paper 4 (Higher)
A sequence of fissions in which a neutron released by one fission triggers another.
Revise: Nuclear fissionA neutron released in one fission may be absorbed by another nucleus that can undergo fission. That nucleus may split and release further neutrons, which may trigger still more fissions. This continuing sequence is a chain reaction.
Paper 1, Paper 2
A sequence of fission events in which neutrons released by one fission cause further nuclei to split.
Revise: Nuclear energyThis repeating sequence is a chain reaction: one fission provides particles capable of triggering later fissions. If enough of the released neutrons go on to produce further events, the number of fissions can increase rapidly. In a nuclear reactor the reaction must be controlled so that energy is released at a manageable rate.