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 U 235 and U 238

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