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PSC 4010

PSC 4010. Nuclear Technology: A matter of Energy. PSC 4010: Chapter 5. Goals: _ SWBAT compare the A-bomb and the H-bomb (components, power, nuclear reaction, effects) _SWBAT compare nuclear power stations with thermal and hydroelectric ones

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PSC 4010

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  1. PSC 4010 Nuclear Technology: A matter of Energy

  2. PSC 4010: Chapter 5 Goals: _ SWBAT compare the A-bomb and the H-bomb (components, power, nuclear reaction, effects) _SWBAT compare nuclear power stations with thermal and hydroelectric ones _SWBAT describe the operation of a CANDU nuclear reactor _SWBAT compare the technology used in CANDU reactors with that used in other countries _SWBAT describe the use of radioactivity in medicine, food irradiation and C-14 dating _ SWBAT compare advantages and disadvantages (and difficulties) of using nuclear fission or fusion to produce electricity

  3. PSC 4010: Chapter 5 Introduction (p. 5.3): Uses for nuclear energy • Medicine • Electrical generation • Military (bombs, submarines, spaceships)

  4. PSC 4010: Chapter 5 Atomic bomb (A-bomb) (p. 5.4 – 5.8): • First tested, and then used (Hiroshima & Nagasaki) in 1945 • Uses nuclear fission • Easily fissionable isotopes (U-235 or Pu-239) as fuel for chain reaction • Critical mass: minimum amount of radioactive matter which produces stable number of fissions over time • Amount of fissionable material can be calculated (more than critical mass, uncontrollable chain reaction; less, chain reaction does not sustain itself in time)

  5. PSC 4010: Chapter 5 Atomic bomb (A-bomb) (p. 5.4 – 5.8): • Fissionable material is separated into two blocks, each with mass < critical mass. • These block are propelled against each other with the detonation of an explosive (dynamite). • The mass of both blocks exceeds critical mass, so chain reaction is uncontrolled • Power of A-bomb is equivalent to 20 000 tons of TNT

  6. PSC 4010: Chapter 5 Atomic bomb (A-bomb) (p. 5.4 – 5.8): Four aspects (consequences) of A-bomb explosion: • Direct radiation (billion of small bullets shot at you, made of all 3 types, alpha, beta, gamma) • Extremely high temperatures • Blast of air (can destroy buildings or dismember animals and human beings) • Contamination of dust

  7. PSC 4010: Chapter 5 Nuclear changes: Practice Exercise Page 5.6, Ex. 5.1 & 5.2 Page 5.8, Ex 5.4

  8. PSC 4010: Chapter 5 Hydrogen bomb (H-bomb) (p. 5.9 – 5.13): • First tested in 1952 • Uses nuclear fusion • Temperature at center of explosion is 5 times that of center of Sun! (Fig. 5.3, p. 5.9) • Thermonuclear bomb (high temperatures needed : millions of degrees) • Using Deuterium and Tritium (H isotopes) can lower T needed • Needs an atomic bomb (nuclear fission) to provide energy for detonation!

  9. PSC 4010: Chapter 5 Hydrogen bomb (H-bomb) (p. 5.9 – 5.13): • Use dynamite to trigger nuclear fission (A-bomb) • Then use temperature and energy from A-bomb to detonate H-bomb (Figure 5.4, p. 5.11) • Fusion of uranium in A-bomb releases neutrons that collide with lithium, and transform it to tritium • Tritium then fuses with deuterium to form helium, releasing SPECTACULARLY LARGE amounts of energy (and neutrons) • No critical mass, therefore no limits of explosive power of H-bomb • Energy produced (fusion) is 3 to 3.5 times that of A-bomb (fission)

  10. PSC 4010: Chapter 5 Nuclear changes: Practice Exercise Page 5.13, Ex. 5.8 & 5.9

  11. PSC 4010: Chapter 5 Use of Nuclear Fission to produce electricity: (p. 5.13 – 5.17): History • 1945 Atomic Energy of Canada Limited (Ontario) • 1955 Canada Energy Program selected principles for CANDU (nuclear reactor) • 1962 first experimental reactor started producing electricity (Ontario) • 1972 first Canadian nuclear station (Pickering One)

  12. PSC 4010: Chapter 5 Use of Nuclear Fission to produce electricity: (p. 5.13 – 5.17): Production • Electrical generator (force into electricity) • Turbine moved by pressurized steam • Figs. 5.5 & 5.6 (pp. 5.14, 5.15) Diagrams of power stations • Fig 5.8, p. 5.16: • 0.5 kg coal, 1.5 kW/h • 0.5 kg gas, 2.0 kW/h • 0.5 kg uranium, 30 000 kW/h

  13. PSC 4010: Chapter 5 Use of Nuclear Fission to produce electricity: (p. 5.13 – 5.17): Operation • Nuclear fission • Uranium (natural or enriched) arranged in rods or bundles (mass below critical to avoid chain reaction) • Cadmium rods are inserted in core of reactor (control rods: absorb neutrons produced which will slow down chain reaction) • Coolant: heats water and turns it into steam (at boiler), which is latter used to move turbine

  14. PSC 4010: Chapter 5 Use of Nuclear Fission to produce electricity: (p. 5.13 – 5.17): Operation • In Canada, coolant is heavy water (D2O, made of Deuterium instead of Hydrogen). It also has the ability to act as moderator, slowing neutrons ejected by core of reactor • In other countries, coolant is ordinary water or gas • Heat after being absorbed by coolant is transported to Boiler (big water reservoir) • Boiler, produces pressurized steam (large T and P) that is sent to rotate the turbine, which is connected to a generator, thus producing the electricity

  15. PSC 4010: Chapter 5 Use of Nuclear Fission to produce electricity: (p. 5.13 – 5.17): Operation • Steam is then cooled down back to water in a condenser, using cold water pumped from outside source • Water is sent to reactor afterwards for new cycle (closed circuit, minimum environment contact) • Fuel bundles are changed during operation, in order to work continuously

  16. PSC 4010: Chapter 5 Power plants comparison:

  17. PSC 4010: Chapter 5 CANDU Reactor (p. 5.18 – 5.20): • CANada, Deuterium, Uranium • Use Cadmium control rods (slow chain reaction) • Use Heavy Water (coolant and moderator / to slow neutrons) • Use natural uranium (nuclear waste, as old ones are replaced by new ones) (*States use enriched uranium) • Work continuously (no interruptions)

  18. PSC 4010: Chapter 5 *Enriched uranium due to higher capacity of ordinary water to absorb neutrons. Thus, higher proportion of U-235 improves fission probability *No containment shell (Cherbnobyl, Ukraine), Containment shell (Three Mile Islan, PA, USA)

  19. PSC 4010: Chapter 5 Nuclear changes: Practice Exercise Page 5.20, Ex. 5.14 - 5.16 Page 5.24, Ex 5.17 & 5.19

  20. PSC 4010: Chapter 5 Slowpoke reactor (p. 5.21): • Miniature nuclear reactor (12 m high) • Household of water with reactor inside • Produces up to 12 MW and 9 liters of waste per year of use

  21. PSC 4010: Chapter 5 Medical applications (p. 5.25 – 5.28): Destruction of cancerous cells • Co-60 destroys tumors ( γ rays), breaks down genetic material _rotate to minimize affectation _many treatments to minimize overdose

  22. PSC 4010: Chapter 5 Medical applications (p. 5.25 – 5.28): Tracers • Detecting rate of absorption of radioactive tracers by an organ, can show proper functioning of said organ (Figure 5.11, p. 5.26) • Must have short half-life to minimize body exposure

  23. PSC 4010: Chapter 5 Food irradiation (p. 5.29 – 5.30): • Co-60 radiations kills microorganisms that can cause food decay • Food does NOT become radioactive (advantage • Changes chemical composition of food, therefore changes it nutritional value (disadvantage)

  24. PSC 4010: Chapter 5 Nuclear changes: Practice Exercise Page 5.30, Ex 5.24 & 5.25

  25. PSC 4010: Chapter 5 Other uses of Nuclear Energy (p. 5.30 – 5.32): Carbon-14 dating _While alive, beings absorb C-12 & C-14 in same ratio _Once dead, C-12 stays, C-14 decays (half life = 5730 years) _C-12/C-14 ratio tells us age of dead tissues

  26. PSC 4010: Chapter 5 Nuclear changes: Practice Exercise Page 5.31, Ex 5.27

  27. PSC 4010: Chapter 5 Other uses of Nuclear Energy (p. 5.30 – 5.32): Submarines _To produce electricity and move propels of submarines _To produce water (electrolysis)

  28. PSC 4010: Chapter 5 Other uses of Nuclear Energy (p. 5.30 – 5.32): Spaceships, cargo planes, boats _To power cargo planes and boats _To power spaceships

  29. PSC 4010: Chapter 5 Use of Nuclear Fusion to produce electricity (p. 5.33 – 5.38): Sun _Natural fusion reactor (hydrogen atoms fuse to deuterium, which fuses with hydrogen to turn into tritium, which fuses with deuterium to form helium) _Earths uses very little of sun’s energy produced, still enough for our needs _Nuclear fusion brings about “Plasma” (4th state of matter)

  30. PSC 4010: Chapter 5 Use of Nuclear Fusion to produce electricity (p. 5.33 – 5.38): Energy associated with fusion (Advantages) _Fusion produces 3 times the energy of Fission for same amount of initial material _No risk of uncontrolled reaction for fusion requires constant heat _Cheap and abundant fuel (deuterium is easily found in sea water) _Process releases very little radiation Energy associated with fusion (Disadvantages) _Temperatures needed are too high (millions of degrees). No material can withstand heat without melting (use of magnetic fields to contained lab-generated nuclear fusion material)

  31. PSC 4010: Chapter 5 The Tokamak fusion reactor: • Very strong electric currents (heat up plasma in middle of contained magnetic field) • Fusion is forced as T and P rise inside reactor • Energy produced boils water into steam and this moves turbines to generate electricity *UK (1991) first ever experimental fusion reactor (two minutes, 1 million Watts worth of energy!)

  32. PSC 4010: Chapter 5 Practice Exercises for Chapter 5: • Page 5.41 – 5.43 – Ex 5.34 – 5.45

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