Read this passage and answer the questions below - Leaving Cert Physics - Question 11 - 2012

Radioactivity is the process by which unstable atomic nuclei lose energy by emitting radiation in the form of particles or electromagnetic waves. This results in the transformation of the original nucleus into a different element or a more stable form.

A nuclear chain reaction occurs when the neutrons released during fission go on to trigger further fission events, leading to a self-sustaining series of reactions. Each fission event releases more neutrons, which can induce further fission in nearby nuclei.

Control rods are used to absorb neutrons and regulate the rate of the nuclear reaction within the reactor. By adjusting their position in the reactor core, operators can increase or decrease the number of available neutrons, thus controlling the power output.

Control rods are typically made of materials with high neutron absorption properties, such as boron, cadmium, or hafnium. These materials help to capture neutrons and thereby reduce the likelihood of further fission events.

Even after the chain reaction is stopped, the reactor continues to generate heat due to the radioactive decay of isotopes created during the fission process. This decay produces residual heat that needs to be managed to prevent overheating.

It is crucial to remove the heat generated to prevent overheating of the reactor core, which could lead to a meltdown. If not managed, the excessive heat can compromise the integrity of the reactor and lead to the release of harmful radioactive materials.

One advantage of nuclear energy is that it produces a significant amount of electricity with a relatively low environmental impact compared to fossil fuels. Nuclear power plants generate large quantities of energy while emitting minimal greenhouse gases.