Chain Reactions
Show The neutrons released by each fission reaction can go on to create further fissions, like a chain that is linked several times – from each chain comes two more
Worked ExampleThe diagram shows the nuclear fission process for an atom of uranium-235. Complete the diagram to show how the fission process starts a chain reaction.Step 1: Draw the neutrons to show that they hit other U-235 nuclei
Step 2: Draw the splitting of the U-235 nuclei to show they produce two or more neutrons
Exam TipYou need to be able to draw and interpret different diagrams of nuclear fission and chain reactions. Generally, things move to the right as time goes on in these diagrams, but it is important to read all the information carefully on questions like this.If you have to draw a diagram in an exam remember that the clarity of the information is important, not how pretty it looks!
Control Rods and Moderators
Diagram of a Nuclear Reactor. The overall purpose of the reactor is to collect the heat energy produced from nuclear reactions Control RodsPurpose of a control rod: To absorb neutrons
ModeratorThe purpose of a moderator: To slow down neutrons
Shielding
Shielding metals in a nuclear reactor What is the role of shielding in a nuclear reactor?A nuclear reactor shield is fitted around the reactor to absorb any radiation from leaking into its immediate environment. Usually made of lead or special types of plastics, shielding is necessary for both the transportation and storage of radioactive neutron sources.
Why is shielding of a reactor necessary What do you understand by thermal shielding?An operating reactor is a powerful source of radiation, since fission and subsequent radioactive decay produce neutrons and gamma rays, both of which are highly penetrating radiations. A reactor must have specifically designed shielding around it to absorb and reflect this radiation in order…
Why is shielding needed in a nuclear reactor GCSE?concrete shield - the daughter products of the fission reaction are radioactive and can be a hazard. The concrete shield stops alpha and beta particles, gamma rays and fast moving neutrons from escaping into the environment of the power station.
Which shield is used in nuclear reactor?Lead is used as a shield in a nuclear reactor. A moderator to slow down fast neutrons. Usually, graphite or heavy water is used as a moderator. For nuclear reactors enriched uranium having nearly 6% U-235 is required.
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