Fission, Fusion & Nuclear Energy — practice questions

Describe what happens during induced nuclear fission of a uranium-235 nucleus.

In a nuclear reactor, explain why control rods are used, and explain what would happen to the reactor's power output if they were withdrawn further.

A reactor uses a moderator and control rods, and its fuel is enriched to increase the proportion of uranium-235. Explain how these three features work together to sustain a controlled chain reaction, linking the role of each to the behaviour of neutrons.

State what nuclear fusion is, and give one example of where it occurs naturally.

Explain why extremely high temperatures are needed for fusion to occur.

Compare fission and fusion as sources of energy for electricity generation, linking the physics of each process to its practical advantages and disadvantages.

A nuclear reaction converts $2.0 \times 10^{-6}$ kg of mass into energy.

Calculate the energy released. ($c = 3.00 \times 10^8$ m s⁻¹)

A reactor releases $7.2 \times 10^{13}$ J of energy in one day.

Calculate its average power output, and calculate the mass converted into energy over that day. ($c = 3.00 \times 10^8$ m s⁻¹)

A nuclear power station releases $1.5 \times 10^{15}$ J of nuclear energy in a day but delivers an average electrical output of $6.0 \times 10^8$ W.

Calculate the mass converted into energy and the efficiency of the station, and explain, in terms of the energy transformations taking place, why the electrical output is so much smaller than the nuclear energy released. ($c = 3.00 \times 10^8$ m s⁻¹)