overview of chapter 12 introduction to nuclear power atoms and radioactivity nuclear fission pros...
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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 atomsTRANSCRIPT
Introduction to Nuclear Power Atoms and radioactivity
Nuclear FissionPros and Cons of Nuclear Energy
Cost of Nuclear Power
Safety Issues at Power Plants Three Mile Island & Chernobyl Nuclear Weapons
Radioactive WasteFuture of Nuclear Power
Nuclear energy
Nuclear fission ______________ of an atomic nucleus into two smaller fragments,
accompanied by the release of a large amount of energyNuclear 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
Nucleus Comprised of protons (+)
and neutrons (neutral)
Electrons (-) orbit around ________________
Neutral atoms Same # of ________________ and
________________
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…
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??
Varies greatly in time
Nuclear Fuel Cycle Processes involved in
producing the fuel used in nuclear reactors and in disposing of radioactive (nuclear) wastes
Uranium ore – mineral fuel used in conventional nuclear power plants __________________________
resource Ore contains 3 isotopes:
U238 (99.28%), U235 (.71%) and U234 (less than 0.01%)
U235 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
Fission releases ______________________ , which transforms water to steam Steam used to generate electricity
Be able to elaborate on imageSafety?
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 _____________________ of an immediate environmental
impact compared to fossil fuels Carbon-free
source of electricity- no ______________________________ emitted
May be able to generate H-fuel
Cons Generates _______________________ waste Many steps require fossil fuels (mining and
disposal)
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
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
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 USTechnological advance could change nuclear
power’s potential contribution in the future
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!!
1979- most serious reactor accident in US50% meltdown of reactor core
Containment building kept radiation from escaping
Elevated public apprehension of nuclear energy Led to ___________________________ of many new plants in US
1986- worst accident in history
1 or 2 explosions destroyed the ______________________________ Large amounts of radiation
escaped into ___________________Spread across large
portions of Europe
Radiation spread was ___________________
Radiation fallout was dumped unevenly
Death toll is 10,000-100,000
Health issues
___________ 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?
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
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
U235 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 Sr90 – chemically similar to Ca; incorporated into bone and teeth Cs137 – replaces potassium in body, accumulates in muscle tissue I131 – concentrates in thyroid gland
_____________________ storage solutions In nuclear plant facility (require high security)
Under water storage Above ground concrete and steel casks
Need approved ______________________ options soon.
70,000 tons of high-level radioactive waste
_______________________ issues have been identified
High level ___________ waste
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)
Fuel= isotopes of hydrogen (deuterium and tritium)
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
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 2025 2011 – 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