The table shows information about three isotopes of uranium.
| Isotope | Proton number | Neutron number | Half-life | Amount in natural uranium |
|---|---|---|---|---|
| Uranium-234 | 92 | 142 | 246,000 years | 0.005% |
| Uranium-235 | [A] | 143 | 700 million years | 0.72% |
| Uranium-238 | 92 | [B] | 4.5 billion years | 99.27% |
State the values that should replace [A] and [B] to complete the table.
Explain what is meant by the term half-life.
Suggest why uranium-238 is the most common isotope of uranium found in nature.
Uranium-235 is commonly used as a fuel in nuclear reactors. What are the products of the nuclear fission of a uranium-235 nucleus when it absorbs a slow-moving neutron?
Explain the purpose of the thick concrete shielding built around the reactor vessel.
Describe the effect on the rate of nuclear fission and temperature when control rods are inserted deeper into the reactor core.
Following a serious incident at a nuclear power plant, radioactive materials can be released into the environment. Explain why it is incredibly difficult to remediate and make the surrounding land safe for human activity again.
