Overview of Chapter 12 Introduction to Nuclear Power  Atoms and radioactivity Nuclear Fission Pros and Cons of Nuclear Energy  Cost of Nuclear Power Safety Issues at Power Plants  Three Mile Island & Chernobyl  Nuclear Weapons Radioactive Waste Future of Nuclear Power

Introduction to Nuclear Energy Nuclear energy  Nuclear fission  ______________ of an atomic nucleus into two smaller fragments, accompanied by the release of a large amount of energy Nuclear fusion  _______________ of two lightweight atomic nuclei into a single, heavier nucleus, accompanied by the release of a large amount of energy Nuclear reactions produce __________________ times more energy per atom than is available from a chemical bond between 2 atoms

Atoms and Radioactivity ~ Basic Structure of Atom Nucleus  Comprised of protons (+) and neutrons (neutral) Electrons (-) orbit around ________________ Neutral atoms  Same # of ________________ and ________________

Atoms and Radioactivity ~ Terminology to Know Atomic mass  Atomic number   Each element has its own atomic number Isotope  Usually an atom has an equal number of neutrons and protons  If the number of neutrons is greater than the number of protons = isotope  Examples…

Radioactive Isotope Unstable isotope  Radioactive Decay  Emission of ______________________________________ particles or rays from unstable atomic nuclei Example  Uranium (U-235) decays over time to lead (Pb-207) Each isotope decays based on its own half-life  What is half-life??

Radioactive Isotope Half-lives Varies greatly in time

Nuclear Fission Nuclear Fuel Cycle  Processes involved in producing the fuel used in nuclear reactors and in disposing of radioactive (nuclear) wastes

Nuclear Fission Uranium ore – mineral fuel used in conventional nuclear power plants  __________________________ resource  Ore contains 3 isotopes:  U 238 (99.28%), U 235 (.71%) and U 234 (less than 0.01%)

Nuclear Fission ~ U 235 is used U 235 composes less than 1% of ore – uranium must be refined to concentration to ~3%  In nuclear reactor fission occurs…  U-235 is bombarded with neutrons  The nucleus absorbs ____________  It becomes unstable and splits into 2 smaller atoms  2-3 neutrons are emitted and bombard another U-235 atom 

How Electricity is Produced Fission releases ______________________, which transforms water to steam  Steam used to generate electricity Be able to elaborate on image Safety?

Breeder Nuclear Fission and MOX BNF- A type of nuclear fission in which non- fissionable U-238 is converted into fissionable Pu-239 What is different? Concerns… US performed first breeder reactor experiments but abandoned nuclear reactor development in 1977 by President Carter Europe, reactors that use mixed oxide fuel (_______________)  Can be used to generate ___________________

Pros and Cons of Nuclear Energy Pros  _____________________ of an immediate environmental impact compared to fossil fuels  Carbon-free source of electricity- no __________________ ____________ emitted  May be able to generate H-fuel

Pros and Cons of Nuclear Energy Cons  Generates _______________________ waste  Many steps require fossil fuels (mining and disposal) 

Cost of Electricity from Nuclear Energy Cost is very ___________________ 20% of US electricity is from Nuclear Energy  Affordable due to government subsidies Expensive to build nuclear power plants  _______________________ cost-recovery time Fixing technical and safety issues in existing plants is _______________________ True costs of nuclear energy are _________________ always obvious in utility bills

Cost of Building In US, no nuclear power plants have been ordered since 1976 for 2 reasons:  Nuclear Power and Electrical Power Deregulation  Prior to late 1990s  During late 1990s – state governments __________________ the electricity market  Early 2000s – amid widely publicized electricity shortages in several states, the market price of electricity soared and nuclear power became more attractive economically

Can we decrease dependency on foreign oil? US concerned about our reliance on _________________________________________ Supports of nuclear energy – it would ______________ our dependence use nuclear power  Not as convincing as sounds – oil generates only _________ of electricity in US Technological advance could change nuclear power’s potential contribution in the future

Safety Issues in Nuclear Power Plants Meltdown  Probability of meltdown or other accident is ______ Public perception is that nuclear power is not safe… why? Sites of major accidents:  Three Mile Island – US  Chernobyl (Ukraine) – global  Japan!!

Three-Mile Island most serious reactor accident in US 50% meltdown of reactor core  Containment building kept radiation from escaping  Elevated public apprehension of nuclear energy  Led to ___________________________ of many new plants in US

Chernobyl worst accident in history 1 or 2 explosions destroyed the _____________ _________________  Large amounts of radiation escaped into ___________________ Spread across large portions of Europe

Chernobyl Radiation spread was ___________________ Radiation fallout was dumped unevenly Death toll is 10, ,000 Health issues

Nuclear Energy and Nuclear Weapons ___________ countries use nuclear energy to create electricity These countries have access to spent fuel needed to make nuclear weapons Safe storage and handling of these weapons is a ________________________ Special concerns of international safety  Russia What has the US done?

Radioactive Waste Low-level radioactive waste  Radioactive solids, liquids, or gasses that give off ____________ __________________________________ __________________________________ High-level radioactive waste  Radioactive solids, liquids, or gasses that give off ____________ __________________________________ __________________________________ Fuel rods – must be stored for _________________ of years

Radioactive Wastes Long term solution to waste  As of 2004, site must meet EPA million year standard (compared to previous 10,000 year standard)  Possibilities:   Deep geologic burial –Yucca Mountain

Radioactive Waste with Short Half Lives U 235 may split in several ways – forms smaller atoms which are ___________________________  The smaller atoms have very short half lives Safe storage of fission products – concern because _________________ produces larger amounts of these materials  Compared to amount with extremely longer half lives Health concerns exist - mimic essential nutrients, concentrate in the body  continue to decay w/ harmful effects  Sr 90 – chemically similar to Ca; incorporated into bone and teeth  Cs 137 – replaces potassium in body, accumulates in muscle tissue  I 131 – concentrates in thyroid gland

Radioactive Waste _____________________ storage solutions  In nuclear plant facility (require high security)  Under water storage  Above ground concrete and steel casks Need approved ______________________ options soon.

Case-In-Point Yucca Mountain 70,000 tons of high-level radioactive waste _______________________ issues have been identified High level ___________ waste

Decommissioning Nuclear Power Plants Licensed to operate for 40 years  Several have received 20-year extensions Power plants ________________ be abandoned when they are shut down Three solutions   Decommissioning (dismantling)

Fusion Fuel= isotopes of hydrogen (deuterium and tritium)

Fusion Way of the future??  Produces ________________ high-level waste  Fuel is _____________________________ (plenty of it!) Problems  It takes very high temperatures (millions of degrees) to make atoms fuse  Confining the __________________________ after it is formed Scientists have yet to be able to create _______________________ from fusion

Future of Nuclear Power Nuclear and utility executives have developed a plan that addresses the safety and economic issues associated with nuclear power  Building a series of “new generation” nuclear reactors New design:  Pebble bed modular reactor (PBMR) – uses small ceramic encased balls of uranium instead of fuel rods 2007 – Bush called for 30 new commercial nuclear power plants to be built between 2015 and – Obama support continuing to explore nuclear power in US Globally:  16 of 25 nuclear power plants currently under construction are in Asia  2004 – France announced intention to replace aging nuclear reactors with new ones