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Give reasons for (a) Ligther elements are better moderators for a nuclear reactor than heavier elements. (b) In a natural uranium reactor, heavy water is prefered moderator to ordinary water. (c) Cadmium rods are provided in a reactor. (d) Very high temperatures as those obtained in the interior of the sun are required for fusion reaction to take place. |
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Answer» Solution :(a) A good moderator has two properties. It slows down neutrons by elastic collision and it dose not remove them form the core by absorbing them. That is why ligther elements are better moderators. (b) Heavy water is used in reactors using natural uranium as FUEL. This is becuase it has lesser absorption probability of neutrons than ordinary water. (c) Cadmium RODS have a high cross section for neutron ansorption. They are used for controlling the nuclear chanin reaction responsible for producing nuclear energy (d) for fusion reactions, very high TEMPERATURES are required. It enables protons to have enough kinetic energy and overcome their mutual electrostatic repulsion and come CLOSER than the range of nuclear forces of attraction. |
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