Modern Physics - Nuclear Physics - SS2 Physics Past Questions and Answers - page 6

Nuclear fission is a process in which the nucleus of a heavy atom, such as uranium-235 or plutonium-239, is split into two smaller nuclei, along with the release of energy and several neutrons. This process is initiated by bombarding the nucleus with a neutron, which causes it to become unstable and split into two daughter nuclei. Additionally, two or three neutrons are released, which can trigger a chain reaction if they collide with other atomic nuclei, leading to a self-sustaining release of energy.

 

Nuclear fission has several applications, including electricity generation in nuclear power plants and the production of weapons in nuclear reactors. The energy released in the form of heat during fission can be harnessed to produce steam, which drives turbines to generate electricity. However, the use of nuclear fission also poses significant challenges, such as the production of radioactive waste that needs careful disposal, the potential for accidents or meltdowns, and the proliferation of nuclear weapons.

Nuclear fusion is a process in which two light atomic nuclei, such as hydrogen isotopes deuterium and tritium, combine to form a heavier nucleus, releasing a tremendous amount of energy. Fusion reactions occur under extreme conditions of high temperature and pressure, typically millions of degrees Celsius and several times the atmospheric pressure. At such high temperatures, the kinetic energy of the particles overcomes the electrostatic repulsion, allowing the nuclei to approach close enough for the strong nuclear force to bind them together.

 

The energy released in nuclear fusion comes from the conversion of mass into energy, following Einstein's famous equation E=mc2. This energy is in the form of high-energy photons (gamma rays) and kinetic energy of the reaction products. Fusion reactions have the potential to provide a practically unlimited and clean source of energy, similar to the processes occurring in the Sun.

 

However, achieving practical fusion reactions poses significant challenges. One major challenge is the need to sustain the extreme conditions of temperature and pressure for a sufficient amount of time to achieve a net energy gain. Another challenge is the confinement and control of the hot plasma required for fusion, as it tends to dissipate and lose energy rapidly. Researchers are exploring different approaches, such as magnetic confinement (tokamaks) and inertial confinement (laser fusion), to overcome these challenges and make fusion a viable energy source.

 

The potential benefits of successful fusion reactions are immense. Fusion can provide abundant and clean energy without the production of long-lived radioactive waste. It utilises widely available isotopes like deuterium, which can be extracted from seawater, and tritium, which can be produced in the reactor itself. Fusion also avoids the risks associated with nuclear proliferation and has the potential to transform the energy landscape, offering a sustainable and carbon-free solution for future generations.