A thermal nuclear reactor uses enriched uranium as its fuel. This is fuel in which the ratio of U-235 to U-238 has been artificially increased from that found in naturally-occurring ore.
Explain the interactions of neutrons with U-235 and U-238 nuclei in a thermal nuclear reactor, describing how each isotope responds.
The amounts of U-235 and U-238 in natural uranium ore decrease over time due to radioactive decay at different rates.
A sample of uranium ore today contains 620 g620\text{ g}620 g of U-238. The mass of U-238 in this sample was greater 3.20×109 years3.20 \times 10^9\text{ years}3.20×109 years ago.
Show that the mass of U-238 in this sample at that time was about 1.02 kg1.02\text{ kg}1.02 kg.
decay constant of U-238 =1.55×10−10 year−1= 1.55 \times 10^{-10}\text{ year}^{-1}=1.55×10−10 year−1
A thermal nuclear reactor requires a minimum of 4.0%4.0\%4.0% of its total uranium mass to be U-235.
3.20×109 years3.20 \times 10^9\text{ years}3.20×109 years ago, the sample from part (b) contained 38 g38\text{ g}38 g of U-235.
Deduce whether the sample had a high enough U-235 content to be used in a thermal nuclear reactor at that time.
128 exam-style questions on AQA A Level Physics Radioactivity (A-level only), covering Rutherford scattering (A-level only), $\alpha$ , $\beta$ and $\gamma$ radiation (A-level only), Radioactive decay (A-level only), Nuclear instability (A-level only), Nuclear radius (A-level only), Mass and energy (A-level only), Induced fission (A-level only), and Safety aspects (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.