A commercial thermal nuclear power station utilizes controlled induced fission of uranium-235 to generate electricity.
Explain why it is necessary to reduce the kinetic energy of fission neutrons before they can initiate subsequent fission events in a thermal reactor.
In a particular moderator material, a newly-produced fission neutron loses 48% of its kinetic energy during each collision with a moderator nucleus. If a neutron is initially released with a kinetic energy of 3.2 MeV3.2\text{ MeV}3.2 MeV, calculate its kinetic energy after five such collisions. Give your answer in eV\text{eV}eV.
The average kinetic energy of fission neutrons must be reduced from approximately 3.2 MeV3.2\text{ MeV}3.2 MeV to thermal energies of about 1 eV1\text{ eV}1 eV. Explain, by considering conservation of momentum and energy in collisions, why the choice of moderator material (specifically the nucleon number of its atoms) affects the number of collisions required to achieve this.
A typical fission reaction occurring within the reactor core is represented by the equation:
92235U+01n→56141Ba+3692Kr+301n ^{235}_{92}\text{U} + ^{1}_{0}\text{n} \rightarrow ^{141}_{56}\text{Ba} + ^{92}_{36}\text{Kr} + 3^{1}_{0}\text{n} 92235U+01n→56141Ba+3692Kr+301nCalculate, in MeV\text{MeV}MeV, the energy released in this single fission event.
Data:
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.