Understanding Nuclear Fusion

Nuclear fusion is a process where two light atomic nuclei combine to form a single heavier nucleus. This process releases a large amount of energy. Nuclear fusion is the power source of stars, including our Sun.

For fusion to occur, the nuclei must overcome their mutual electrostatic repulsion, which requires extremely high temperatures and pressures.

Which Elements Undergo Nuclear Fusion?

Nuclear fusion typically involves isotopes of light elements, most commonly hydrogen isotopes like Deuterium and Tritium. These light nuclei have less positive charge, making it easier for them to get close enough to fuse compared to heavy nuclei.

Analyzing the Options for Nuclear Fusion Candidates

• Thorium: Thorium is a heavy radioactive metal. While it is used in some nuclear reactors, it is primarily associated with nuclear fission (splitting heavy nuclei), not fusion.
• Krypton: Krypton is a noble gas, which means it is chemically inert and does not readily participate in nuclear reactions like fusion or fission.
• Deuterium: Deuterium ($\text{}^2\text{H}$ or D) is a stable isotope of hydrogen. Its nucleus contains one proton and one neutron. Because it is an isotope of hydrogen, a very light element, Deuterium is a prime candidate for nuclear fusion reactions. For example, the Deuterium-Tritium (D-T) reaction is one of the most promising for future fusion reactors.
• Uranium: Uranium is a very heavy radioactive metal, famously used as fuel in nuclear power plants and in nuclear weapons. Like Thorium, Uranium undergoes nuclear fission, not fusion.

Why Deuterium is Suitable for Nuclear Fusion

Deuterium, being a light isotope of hydrogen, has a relatively low positive charge on its nucleus. This makes it possible to achieve the conditions necessary for fusion at temperatures and pressures that are currently attainable (though still extremely high) in laboratory settings aimed at controlled fusion power. The most commonly studied fusion reactions involve Deuterium combining with Tritium (another hydrogen isotope) or with another Deuterium nucleus.

Therefore, among the given options, Deuterium is the one that can undergo nuclear fusion.