1. Nuclear Reactors and Nuclear Energy Conversion of mass-energy to electrical energy mass-energy  thermal  kinetic  electric Produces large amounts of electrical energy for large-scale use (city, province, country) small-scale: submarines, large ships Energy released by Fission of Uranium-235 Reactions occur in Nuclear Reactor Electricity produced by spinning electric generator

2. Nuclear Reactor www.ems.psu.edu/~pisupati/ cbc.ca Pickering Nuclear Power plant

3. Fuel Natural uranium: 99% uranium-238, 1% uranium-235 Energy produced by chain reaction (nuclear decay produces neutrons that can initiate other reactions) U-238 cannot produce chain reaction, U-235 can Nuclear fuel = 3 – 5 % U-235 (enriched uranium) Uranium formed into fuel pellets Fuel pellets inserted in fuel rods, fuel bundles www.nti.org www.virginmedia.com/digital/science/pictures/

4. Moderator neutrons produced by fission may be too fast to initiate decay slowed down by a moderator ordinary water can slow down neutrons (but can absorb many) heavy water (D 2 O) slows down neutrons without absorbing Control Rods rate of reactions controlled by material that absorbs neutrons (cadmium, boron) rods inserted into fuel bundle to slow or allow reactions (prevents overheating) reference.findtarget.com/ commons.wikimedia.org

5. The Core core = fuel bundles, control rods, immersed in coolant coolant (water) pumped into core, absorbs heat from reactions coolant pumped to steam generator heat from coolant boils water Steam steam used to turn turbine steam condensed back to water using cool water (lake or river) 3 separate water circuits  core  turbine  cooling www.hk-phy.org/energy/power/

6. Energy Output Large scale: CANDU reactor – 800 MW per reactor  Power plant = several reactors Bruce Power (Lake Huron): 8 reactors (enough for 20% of Ontario’s hospitals, homes, schools) More than 50% of Ontario’s electricity produced by nuclear Submarines, ships about 100 MW CANDU Canada Deuterium Uranium Designed in 1950’s Uses natural uranium U-238 can produce plutonium-239, which also produces chain reactions Uses heavy water as moderator www.nucleartourist.com/type/candu2.htm

7. Safety Reactors buildings heavily shielded by concrete and steel Interior at low air pressure so material won’t leak Uncontrolled reactions could lead to  meltdown (Three Mile Island 1979)  explosion (Chernobyl 1986) – releases radioactive material to atmosphere Reactions can be stopped quickly by  dumping moderator  dropping control rods into core www.wired.com/wiredscience/2009/05/threemile/ toxipedia.org/display/toxipedia/Chernobyl+Accident

8. Environmental Concerns rods removed when useful reactions too low (“spent” fuel) still radioactive, with some long half-life isotopes  stored in large pools of water  later removed to dry storage  sometimes stored in glass (vitrification)  could eventually be stored deep underground  possibly contaminate environment if leaked heat from cooling process could alter marine ecosystems www.world-nuclear.org/info/inf04.html www.biopxenor.com/tag/nuclear-waste-storage

9. CountryMegawatt capacity Nuclear share of electricity production France63,23675.2% Slovakia1,76053.5% Belgium5,94351.7% Ukraine13,16848.6% Slovenia and Croatia69637.9% + 8.0% Armenia37645.0% Hungary1,88043.0% Switzerland3,25239.5% Bulgaria1,90635.9% Korea, South (ROK)17,71634.8% Sweden9,39934.7% Czech Republic3,68633.8% Finland2,72132.9% Japan47,34828.9% Germany20,33926.1% Taiwan (ROC)4,92720.7% Romania1,31020.6% United States101,22920.2% United Kingdom10,96217.9% Russia23,08417.8% Spain744817.5% Canada12,67914.8% Argentina9357.0% Mexico1,3104.8% South Africa1,8004.8% Netherlands4853.7% Brazil1,9013.0% Pakistan4002.7% India4,7802.2% China (PRC)10,2341.9% World376,31314% http://en.wikipedia.org/wiki/Nuclear_power_by_country