Nuclear Fission and Fusion: Answers
Describe how nuclear fission can result in a chain reaction.
When a radioactive nucleus splits apart into two smaller nuclei, it also releases two to three neutrons. If these neutrons are absorbed by other unstable nuclei, it will make them even more unstable and cause them to also split into two daughter nuclei and also release two to three neutrons. This process continues in a chain reaction until all of the radioactive nuclei are used up.
How does a nuclear reactor generate electricity?
A nuclear reactor contains radioactive fuel, such as uranium or plutonium. A neutron is absorbed by a uranium nucleus and causes it to undergo nuclear fission. When the uranium nucleus splits, it releases neutrons which have kinetic energy. The kinetic energy is converted into heat energy and used to turn water into steam. The steam drives a turbine which is connected to a generator to produce electricity.
What is the purpose of the following in a nuclear reactor: control rods, moderator, concrete shield.
The control rods absorb some of the neutrons released during nuclear fission so that the chain reaction doesn’t get out of hand and only one neutron is released per nuclear fission event.
The moderator slows down the neutrons so that they are more easily absorbed by other radioactive nuclei.
The concrete shield prevents radiation from reaching outside the reactor. It is a safety precaution.
What is the difference between nuclear fission and nuclear fusion?
Nuclear fission is when a large radioactive nucleus splits apart into two smaller, more stable nuclei. Nuclear fusion is when two small nuclei join to form a larger one. It happens in stars and provides the energy for stars to keep burning.
Give some advantages and disadvantages of nuclear power.
The advantages of nuclear power are that is requires only small amounts of fuel, the fuel is fairly cheap and no polluting gases (such as carbon dioxide) are produced during the process. The nuclear power stations also last a long time.
The disadvantages are that it produces radioactive waste which needs to be carefully disposed of so that it doesn’t contaminate drinking water and harm human health. It also produces a lot of hot water which can harm marine life if it is returned to local rivers and streams. Accidents at nuclear power plants can be catastrophic, as seen at the Chernobyl power plant in Ukraine in the 1980s. Several people died after an explosion at the power plant and whole towns had to be evacuated. Finally, nuclear power plants can only provide a steady level of electricity and cannot adjust their output according to demand.