Chapter 12 Nuclear

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Definitions Combustion- Nuclear- Fission- Fusion-

Nuclear reactions produce _______x more than energy per atom than chemical reaction Nuclear reactions produce _______x more than energy per atom than chemical reaction The atom The atom Atomic Mass- Atomic Number- Atomic Mass- Atomic Number-

More Definitions Isotopes- forms of a single element that differ in atomic mass (due to different # of neutrons) Isotopes- forms of a single element that differ in atomic mass (due to different # of neutrons) Radioisotopes- unstable isotope that spontaneously emit a form of energy consisting of particles (radiation) Radioisotopes- unstable isotope that spontaneously emit a form of energy consisting of particles (radiation) Radioactive Decay- process of a radioisotope emitting radiation whose nucleus changes into the nucleus of a different element as a result of the radiation Radioactive Decay- process of a radioisotope emitting radiation whose nucleus changes into the nucleus of a different element as a result of the radiation Radioactive half-life- period of time required for one half of the total amount of a radioactive substances to change into different material (daughter product) Radioactive half-life- period of time required for one half of the total amount of a radioactive substances to change into different material (daughter product) Nuclear power plants use fission. Nuclear power plants use fission.

Nuclear Fission Uses uranium as fuel Uses uranium as fuel Non-renewable resourcesNon-renewable resources Found predominantly in_______________________)Found predominantly in_______________________)

3 main uranium isotopes 3 main uranium isotopes U-238:U-238: U-235:U-235: U-234:U-234:

Fission Process Enriched uranium (U-235) ore formed into pellets & placed in fuel rods Enriched uranium (U-235) ore formed into pellets & placed in fuel rods Fuel rods put into fuel assemblies & placed in reactor vessel Fuel rods put into fuel assemblies & placed in reactor vessel Reaction controlled by control rod Reaction controlled by control rod In fission process, U-235 is bombarded w/ neutrons which splits the atom releasing energy & daughter product In fission process, U-235 is bombarded w/ neutrons which splits the atom releasing energy & daughter product

Energy is in form of heat => used to form steam & generate electricity (steam turns turbine which turns generator which makes electricity) Energy is in form of heat => used to form steam & generate electricity (steam turns turbine which turns generator which makes electricity) Fission occurs in reactor core Fission occurs in reactor core Condenser used to cool steam Condenser used to cool steam

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Water cooling 3 water circuits 3 water circuits Primary (closed)-Primary (closed)- Secondary (closed)-Secondary (closed)- Tertiary-Tertiary- Reactor vessel and generator/water system are in containment building Reactor vessel and generator/water system are in containment building

Breeder Nuclear Fission Alternate type of nuclear fission Alternate type of nuclear fission Uses U-238 and changes it into Pu (plutonium) -239 to use as a fuel in the reactor Uses U-238 and changes it into Pu (plutonium) -239 to use as a fuel in the reactor Breeder reactors use have many safety problems. Main one is use of liquid sodium as coolant (a highly reactive metal that explodes when in contact with water and burns spontaneously in air at high temperature) Breeder reactors use have many safety problems. Main one is use of liquid sodium as coolant (a highly reactive metal that explodes when in contact with water and burns spontaneously in air at high temperature) Plutonium also used in nuclear weapons Plutonium also used in nuclear weapons

What are the advantages and disadvantages of Nuclear Power? Advantage of nuclear- Advantage of nuclear- Disadvantage- Disadvantage-

Nuclear Power in US ___ nuclear power plants in US (434 world wide) supply ___% of nations electricity ___ nuclear power plants in US (434 world wide) supply ___% of nations electricity Nuclear plants regulated by US Department of Energy, Nuclear Regulator Agency Nuclear plants regulated by US Department of Energy, Nuclear Regulator Agency

Internationally- Int’l Atomic Energy Agency (IAEA) Internationally- Int’l Atomic Energy Agency (IAEA) Effects of ionizing radiation (contains enough energy to eject electrons from atoms) damages DNA (mutations) resulting in birth defects, mental retardation or genetic disease Effects of ionizing radiation (contains enough energy to eject electrons from atoms) damages DNA (mutations) resulting in birth defects, mental retardation or genetic disease Mutations in genes controlling cellular growth may convert them oncogenes (genes that cause cancer) Mutations in genes controlling cellular growth may convert them oncogenes (genes that cause cancer)

What do we do with the waste? #1 problem with plants = #1 problem with plants = 2 types of waste 2 types of waste 1. Low-level radioactive wastes- radioactive solids, liquids and gases that give off small amounts of ionizing radiation and include glassware, food, paper, clothing, etc. 2. High-level radioactive wastes- radioactive solids, liquids and gases that initially give off large amounts of ionizing radiation and include reactive metals, coolants fluids and reactor gases

1980 Low-level Radioactive Policy Act 1980 Low-level Radioactive Policy Act Specified all states are responsible for the wastes they generate and encourage states to develop faculties to handle low-level wastesSpecified all states are responsible for the wastes they generate and encourage states to develop faculties to handle low-level wastes No permanent facility for high-level wastes (Yucca Mountain is proposed location) No permanent facility for high-level wastes (Yucca Mountain is proposed location) 72 temporary sites in US 72 temporary sites in US 1982 Nuclear Waste Policy Act- requires federal government to find permanent disposal site and be operational by Nuclear Waste Policy Act- requires federal government to find permanent disposal site and be operational by 1998

Cons of Yucca Mountain Near volcano and earthquake fault line Near volcano and earthquake fault line Transportation of high level wastes is a problem Transportation of high level wastes is a problem Pros of Yucca Mountain Dry area=>deep ground water Dry area=>deep ground water Only site currently under consideration and it is safe Only site currently under consideration and it is safe

Decommissioning (closing) Nuclear Power Plants Storage-Entombment-Decommission-

Radioactive Waste Disposal 1. Liquid wastes- highly unstable and difficult to monitor: must be converted to solid form via “vitrification” (conversion to solid glass or ceramic logs) 2. Solid Waste- Consolidation and storage/monitoring underground

Fusion Combining 2 lighter atoms into one large one producing very large amounts of energy Combining 2 lighter atoms into one large one producing very large amounts of energy Animation Animation Animation Isotopes of hydrogen (heavily hydrogen or deuterium) used for the process Isotopes of hydrogen (heavily hydrogen or deuterium) used for the process Radioactive Tritium is formed by fusion (man-made; not found in nature) Radioactive Tritium is formed by fusion (man-made; not found in nature) Tritium and deuterium formed together to create energy and Helium-4 Tritium and deuterium formed together to create energy and Helium-4

Fusion Advantage- no high-level radioactive wastes (low-level wastes produced) Advantage- no high-level radioactive wastes (low-level wastes produced) #1 problem- requires very high temperature #1 problem- requires very high temperature #2 problem- confining fuel #2 problem- confining fuel Super heated ionizing gas (plasma) has tendency to expand and nuclei aren’t close together and will lose energy when hit container wall magnetic fields for containment)Super heated ionizing gas (plasma) has tendency to expand and nuclei aren’t close together and will lose energy when hit container wall magnetic fields for containment)