Fission and fusion：練習問題

Which of the following describes the process of nuclear fusion as it occurs in stars?

Which of the following statements correctly identifies the energy changes and products in the fission of a Uranium-235 nucleus?

Nuclear fusion requires extremely high temperatures and pressures to occur. Why is it not possible for fusion to happen under standard conditions on Earth?

In a nuclear fission reactor, the moderator is a crucial component. What is its primary function in maintaining the reaction?

In the construction of a nuclear fission reactor, shielding is a critical safety component.
Explain the purpose of this shielding and state one material commonly used for its construction.

In a nuclear reactor, the fission of Uranium-235 is controlled to maintain a steady rate of energy release. (a) Explain the specific function of the moderator in terms of the kinetic energy of neutrons. (b) Describe how control rods are used to stop the reactor in an emergency.

Nuclear fusion involves the joining of smaller nuclei to form a larger nucleus.
Explain why high temperatures and pressures are required for this process to occur, specifically referencing the forces between protons.

In a nuclear power station, the fission of Uranium-235 is a controlled process used to generate electricity.
(a) Explain how the fission of one U-235 nucleus can lead to a chain reaction.
(b) The reactor core contains control rods and a moderator. Describe the purpose of each of these components in maintaining a safe and steady reaction.

Nuclear fusion and nuclear fission are two different types of nuclear reactions that release large amounts of energy.
(a) Define nuclear fusion and explain why this process results in the release of energy.
(b) Nuclear fusion is the process that powers stars. Explain why it is extremely difficult to recreate this process on Earth, specifically referring to the conditions of temperature and pressure.
(c) Compare the nuclei used as "fuel" in a typical fission reactor with the nuclei used in a fusion reaction in a star.