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 _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

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

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)

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 tons of TNT

PSC 4010: Chapter 5 Atomic bomb (A-bomb) (p. 5.4 – 5.8): Four aspects (consequences) of A-bomb explosion: 1.Direct radiation (billion of small bullets shot at you, made of all 3 types, alpha, beta, gamma) 2.Extremely high temperatures 3.Blast of air (can destroy buildings or dismember animals and human beings) 4.Contamination of dust

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

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!

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)

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

PSC 4010: Chapter 5 Use of Nuclear Fission to produce electricity: (p – 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)

PSC 4010: Chapter 5 Use of Nuclear Fission to produce electricity: (p – 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, kW/h

PSC 4010: Chapter 5 Use of Nuclear Fission to produce electricity: (p – 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

PSC 4010: Chapter 5 Use of Nuclear Fission to produce electricity: (p – 5.17): Operation  In Canada, coolant is heavy water (D 2 O, 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

PSC 4010: Chapter 5 Use of Nuclear Fission to produce electricity: (p – 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

PSC 4010: Chapter 5 Power plants comparison: HydroelectricThermalNuclear CondenserNAYes E producedPotential Energy (Water) Chemical Change *operates with coal *contributes to acid rain Nuclear Change Pollution / WasteNAYes TurbineYes BoilerNAYes CoolantNA Yes Steam to move turbine NAYes

PSC 4010: Chapter 5 CANDU Reactor (p – 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)

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) Reactor Component CanadaUSAUK (England) Russia FuelNatural Uranium Enriched Uranium* ModeratorHeavy WaterOrdinary Water Graphite CoolantHeavy WaterOrdinary Water Pressurized Gas Ordinary Water

PSC 4010: Chapter 5 Nuclear changes: Practice Exercise Page 5.20, Ex Page 5.24, Ex 5.17 & 5.19

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

PSC 4010: Chapter 5 Medical applications (p – 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

PSC 4010: Chapter 5 Medical applications (p – 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

PSC 4010: Chapter 5 Food irradiation (p – 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)

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

PSC 4010: Chapter 5 Other uses of Nuclear Energy (p – 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

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

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

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

PSC 4010: Chapter 5 Use of Nuclear Fusion to produce electricity (p – 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” (4 th state of matter)

PSC 4010: Chapter 5 Use of Nuclear Fusion to produce electricity (p – 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)

PSC 4010: Chapter 5 The Tokamak fusion reactor: 1.Very strong electric currents (heat up plasma in middle of contained magnetic field) 2.Fusion is forced as T and P rise inside reactor 3.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!)

PSC 4010: Chapter 5 Practice Exercises for Chapter 5:  Page 5.41 – 5.43 – Ex 5.34 – 5.45