2. What is a Fission Reactor?What is a Fission Reactor?  The Principles of Fission Reactors are similar to that of an Atomic Reactor  Fission Reactors are more controlled  Produces fissions one neutron after another when the reactor reaches a certain power level, maintaining the reaction at a steady rate  Occurs as neutrons strikes a larger nucleus (U-235) whilst being absorbed by it  Large shielded structures utilising control of fission of uranium or plutonium for heat production used to generate electricity

3. Types of Fission ReactorsTypes of Fission Reactors  There are two types of Chain Reactions that occur within a Fission Reactor:  Controlled Chain Reactions  Uncontrolled Chain Reactions

4. Basic Reactor ElementsBasic Reactor Elements  The Basic Elements of a Fission Reactor consists of the following:  Fuel Rods  Moderator  Control Rods  Coolant

5. Fuel RodsFuel Rods  The types of fuel used in fission reaction must be burned in order to derive nuclear energy.  Most materials are formed and composed into fuel rods mixed with structural moderation or neutron reflecting materials.  Contains heavy amount of fissile elements that are capable of nuclear fission reaction as they are capable of emitting neutrons that break apart when struck.  Sustains chain reactions that releases energy with controlled or uncontrolled rates.  Common fuel rods include Uranium-235 and Plutonium-239.

6. Moderator  The moderator is a medium that reduces the speed of fast moving neutrons from approx. 1 MeV to 0.5 eV through multiple collisions  Converts into thermal neutrons in order to sustain a nuclear chain reaction that involves uranium-235.  Water, Graphite, Helium, Beryllium and Sodium are commonly used moderators in a Fission Reactor.  Causes slow moving neutrons to become unstable which then splits into fissions.  Fills space between fuel rods in thermal reactors.  Neutrons of fissionable material captured by atoms will undergo fission

7. Control RodsControl Rods  U sed to control the rate of fission of uranium and plutonium.  Made of chemical elements capable of absorbing neutrons without fission including:  Silver  Indium  Cadmium  Removed or inserted into central cores of a nuclear reactor in order to control the neutron flux which then further splits up uranium atoms.  Affects thermal power of the reactor, amount of steam produced and electricity generated.  Partially removed from the core to allow chain reactions.  Number of rods inserted and displacement distance determines the control of the reactivity of the reactor.

8. Coolant  Used to transfer heat from reactor core during fission.  Circulated around the core in order to absorb heat from neutrons and fission products.  Transfers heat to separate water or steam system, driving conventional turbine electricity generators.  Most coolants consist the use of water under high pressure