Chapter 16 – Nuclear Energy

1. Chapter 16 – Nuclear Energy Alternate to Fossil Fuels

2. 16.1 Atoms and Radioactivity • All matter consists of atoms • All atoms contain: • Protons ( + charge) found in nucleus • Electrons (– charge) orbit around the nucleus • Neutrons (neutral charge) found in nucleus

3. 16.1 Atoms and Radioactivity • Atomic number equals the number of protons and electrons in one atom of any element • Atomic Mass is the amount of stuff contained in one atom of an element • Subtract the Atomic number from the Atomic mass to get the number of neutrons

4. 16.1 Atoms and Radioactivity • Isotope: • Atoms of the same element can have different Atomic masses. • The mass changes because nucleus has a different number of neutrons • Ex: Uranium has isotope of U235 and U238

5. 16.1 Radioactivity • Isotopes can be stable or unstable • Unstable isotopes release energy in the form of protons or neutrons to become stable • Marie Curie – Nobel scientist, was the first person to use radioactive to describe the release of energy

6. 16.1 Radioactivity • Three kinds of energy given off by radioactive isotopes are • Alpha particles (2 protons and 2 neutrons) changes atomic mass and number or radioactive decay • Beta particles (high speed electrons) • Gamma rays (electromagnetic radiation)

7. 16.1 Radioactivity • Half-Life • The amount of time in which half of the atoms in a sample of radioactive element. • Radioactive compounds take from days to thousands of years to lose only one-half of their total radioactive energy

8. 16.2 Reactions and Reactors • Nuclear fission: reaction where the nucleus of a large atom breaks into smaller nuclei • The fission of U235 shows how a neutron hits the Uranium nucleus causing it to split into two smaller (daughter) nuclei and release two neutrons to hit two more Uranium atoms in a chain reaction

9. 16.2 Nuclear Reactors NUCELAR REACTORS PRODUCE ELECTRICITY • FISSION OF U235 PRODUCES HEAT • HEAT BOILS WATER TO MAKE STEAM • STEAM TURNS TURBINES WHICH GENERATE ELECTRICITY

10. Parts of a Nuclear Reactor • Fisson takes place in a REACTOR VESSEL • The U235 in packed into FUEL RODS • The rods are surrounded by WATER that COOLS and SLOWS NEUTRONS • CONTROLL RODS slow down the reaction • The heated water produces STEAM that turns the TURBINES that generate ELECTRICITY

11. Breeder Reactors • Breeder Reactors can PRODUCE THEIR OWN FUEL • Uses Plutonium239 core surrounded by stable Uranium238. • Uranium captures a neutron from Plutonium and becomes U239 which is unstable • This CHAIN REACTION between Plutonium and Uranium produces energy and heat

12. Radioactive Waste • Nuclear power plants produce lots of HIGH-LEVEL radioactive waste such as fuel and control rods, coolant (water or sodium) and the reactor vessel. • High-level waste can cause burns, severe DNA damage, radiation sickness and death • Hospitals, mining, contaminated clothing from power plants are considered MEDIUM-LOW LEVEL radioactive waste. • Low-level waste causes DNA damage, increased risk of cancer and other health problems

13. RADIOACTIVE Waste Disposal • HALF-LIFE of most radioactive compounds is hundreds to thousands of years. • U235 has a half-life of 4.5 BILLION years • Plutonium239 has a half-life of 24,000 years • They will be toxic for generations to come. • Bury low and medium-level wastes (Yucca Mountain –Utah) • High-level wastes are stored at the nuclear reactors