7 3 fission and fusion

Three sources of nuclear energy are:

True. In both fusion and fission, the mass of the original nuclei is greater than the mass of the products. This missing mass has been converted into energy.

True. Nuclear reactions such as fission and fusion can be used to generate electricity. Fission reactors are already in use in nuclear power plants around the world.

Nuclear fission is the splitting of a large nucleus into two smaller nuclei.

True. Neutrons and gamma radiation can be released in nuclear fission reactions.

False. In a nuclear equation to represent a nuclear fission reaction, a neutron can be represented by .

A nuclear chain reaction occurs when

True. Uranium-235 is an example of a fissile material, this means it can undergo fission reactions - its nuclei can be split apart into smaller nuclei.

False. Only one neutron is required to induce fission in a uranium-235 nucleus.

If the amount of nuclear fuel in a fission reactor is too low, chain reactions will stop or slow down. This is because neutrons can escape the material without hitting any more nuclei.

If the amount of nuclear fuel in a fission reactor is too high, chain reactions increase rapidly. If uncontrolled, this can lead to a huge release of energy or even a nuclear explosion.

The purpose of control rods is to absorb neutrons.

The purpose of a moderator is to slow down neutrons.

In a nuclear reactor, neutrons must be slowed down so they can react with the uranium fuel efficiently. This is because slow neutrons are more likely to be absorbed by a uranium nucleus than fast neutrons.

False. Lowering the control rods decreases the rate of fission as more neutrons are absorbed.

The purpose of shielding is to absorb hazardous radiation.

Nuclear fusion is the joining of two smaller nuclei to form one larger nucleus, releasing a large amount of energy in the process.

False. The equation shows a nuclear fusion reaction

False. In a nuclear fusion reaction, the mass of the fused nucleus is less than the mass of the two nuclei that fused together. The remaining mass has been converted to energy.

False The amount of energy released during nuclear fusion is huge.

The type of reaction shown in the nuclide equation is nuclear fission.

False. The energy produced during nuclear fusion comes from a very small amount of the particle’s mass being converted into energy.

Nuclear reactions take place in the centres (cores) of stars.

The Sun is powered by the nuclear fusion of hydrogen into helium.

True. The outward force provided by nuclear fusion reactions prevents stars from collapsing under gravity.

True. Nuclear fusion requires extremely high temperatures to maintain.

The two conditions required for nuclear fusion to occur are: