Binding energy + Nuclear reactor 2.0 / 5 based on 1 rating ? PhysicsParticle physicsA2/A-levelAQA Created by: LZ95Created on: 24-05-14 20:13 What is the definition of binding energy? Work done to separate a nucleus into its constituent neutrons + protons 1 of 32 What is the definition of binding energy per nucleon? Average work done per nucleon to remove all the nucleons from the nucleus 2 of 32 A nucleus with more binding energy per nucleon is... more stable 3 of 32 What is nuclear fission? Large unstable nucleus splits into two stable fragments 4 of 32 What is nuclear fusion? Fusing small nuclei together to form a larger one 5 of 32 What is the mass defect? Difference between the mass of the separated nucleons and the nucleus 6 of 32 What is the equation for mass defect? /\m=Zmp + (A-Z)mn - Mnuc where Z=no. of protons A=no. of nucleons and Mnuc=mass of nucleus 7 of 32 What is electron capture? Nucleus emits a neutrino which carries away energy released in the decay 8 of 32 What is alpha decay? Nucleus recoils when alpha particle is emitted and energy is shared between nucleus + alpha particle 9 of 32 How is energy shared in B decay? Energy released is shared in equal amounts between Beta particle, nucleus +neutrino/antineutrino 10 of 32 What is significant about the total mass after a reaction? It is always less than before as mass turns to energy 11 of 32 What happens in annihilation? Particle + corresponding antiparticle meet, producing two gamma photons each with E=mc^2 12 of 32 Why must particles collide at high speed in nuclear fusion? To overcome electrostatic repulsion 13 of 32 What happens to binding energy after nuclear fusion? It increases 14 of 32 What happens in induced fission? Uranium-235 bombarded with neutrons, splitting it into two equal fragments. 15 of 32 What are released during induced fission and what do they create? Fission neutrons which cause a chain reaction that causes fission, leading to lots of energy being released 16 of 32 What does the moderator do in a thermal nuclear reactor? It slows the electrons down 17 of 32 What does the kinetic energy of the moderator roughly equal to? The K.E. of the neutrons 18 of 32 What do fuel rods contain? Enriched uranium 19 of 32 Out of U-238 and U-235, which one is fissionable and which one is non-fissionable? U-238 = non fissionable, U-235 = fissionable 20 of 32 Why must the enriched uranium be above a critical mass? If the mass is too small, the surface area to mass ratio will be large so more neutrons will escape 21 of 32 What do control rods do? Absorbs neutrons (1 fission neutron per fission is used) 22 of 32 What is the relationship between the depth that the control rods are pushed in and the rate of fission? Further in the control rods are the lower the rate of fission 23 of 32 What happens when the emergency shut down system activates? Control rods are fully inserted into the core, stopping fission completely 24 of 32 Why is it safe to use a thick steel vessel as the reactor core? It withstands high pressure and temperature and absorbs Beta radiation and some gamma radiation as well 25 of 32 What radiation is produced before the use of rods and after? Before: alpha, After: Beta and gamma 26 of 32 What high level radioactive waste does the nuclear reactor produce? Spent fuel rods which contain fission fragments, unused U-235 and U-238 and Plutonium-239. 27 of 32 How do spent fuel rods get disposed of? They have to be stored underwater for many years 28 of 32 What intermediate level radioactive waste does the nuclear reactor produce? Radioactive materials with low activity and containers of radioactive materials 29 of 32 How are these disposed of? They are sealed in drums encased in concrete 30 of 32 What low level radioactive waste does the nuclear reactor produce? Lab equipment + protective clothing 31 of 32 How are these disposed of? Sealed in metal drums + buried in large trenches 32 of 32
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