flung radioactive debris and dust high into atmosphere
cause of accident
most automatic safety and warning systems were turned off
safety design was inadequate
design flaw led to unstable operation at low power
response to accident
after explosion
remains of reactor encased in 19-story concrete tomb
new tomb is needed
estimated cost is $1.5 billion
Ukrainian government cannot afford
consequences of accident
evacuation
~116,000 people
immediate deaths & injuries
31 fatalities
500 hospitalizations
237 with acute radiation sickness
long-term death toll
Ukrainian government official total
3,576 (in 1998)
Greenpeace Ukraine
32,000 as of 1995
long-term health issues
Belarus (70% of radiation was deposited)
thyroid cancer rates among children are 10-100 times the level before the accident
rates of non-cancer diseases increasing disproportionately among ~600,000 "liquidators"
environmental impacts
lethal doses of radiation
long-term contamination
public opinion
percent of people opposed to nuclear power plants before versus after Chernobyl
UK: before, 65% - after, 83%
Germany: before, 46% - after, 83%
US: before, 67% - after, 78%
nuclear plant orders
were declining even before Chernobyl
since 1980 many countries have cancelled nuclear plant orders:
Argentia, 4 plants
Brazil, 8 plants
Mexico, 18 plants
US, 54 plants (no new plants have been ordered since 1974)
a major nuclear accident anywhere is a nuclear accident everywhere
Nature of nuclear energy
nuclear energy
energy from disintegrating atomic nuclei
some isotopes of atoms are
radioactive
radioactive half-life
time it takes for 1/2 of radioactive material to spontaneously decompose
radiation
energy released from nucleus during nuclear disintegration
three major types
alpha
beta
gamma
nuclear fission
process in which moving neutrons hit nuclei of certain other atoms, causing them to split
nuclear chain reaction
critical mass
two materials most commonly used are
uranium-235
plutonium-239
will continue until
fuel is spent
neutrons are prevented from striking other nuclei
History of nuclear energy
first controlled fission
atomic bombs
nuclear weapon research and testing
construction of world’s 1st electricity-generating reactor,
explosion of nuclear devices by India and Pakistan
1950’s predictions
by President Dwight D. Eisenhower, in "Atoms for Peace" speech , 1953
"Nuclear reactors will produce electricity so cheaply that it will not be necessary to meter it . The users will pay an annual fee and use as much electricity as they want. Atoms will provide a safe, clean and dependable source of electricity."
by researchers
by the year 2000, at least 1800 nuclear power plants will supply 21% of world’s commercial energy (25% of US’s energy)
2004 reality
nuclear is the most expensive method of producing electricity
several accidents have caused worldwide concern
no new plants ordered since 1974
in 2000, plants supply 16% of world and 20% of US electricity
some predict use of nuclear energy
to decline as existing plants age and are retired
to increase as concern over greenhouse gas emissions from fossil fuels increases
Nuclear reactor
device that permits a controlled fission chain reaction
controlling the reaction
reactors contain
fuel rods
control rods
moderator
in generation of electricity
serves the same function as any fossil-fuel boiler
reactors
differ in
moderator used
cooling of reactor core
how heat from core is used to generate steam
types
fission
breeder
fusion
fission reactors
major types
light-water reactors (LWR)
boiling-water reactors (BWR)
pressurized-water reactors (PWR)
heavy-water reactors (HWR)
gas-cooled reactors (GCR)
breeder reactors
nuclear fission reactor that
produces heat to be converted to steam to generate electricity
forms a new supply of radioactive isotopes
type
liquid metal fast-breeder reactor (LMFBR)
after ~10 years of operation, enough plutonium-239 is produced to operate a second reactor
reactions can be difficult to regulate
high potential for accidents
waste is very hazardous
plutonium-239 can be made into weapons
only 5 such plants exist in world
only 1 in US is experimental and scheduled to be shut down
nuclear fusion
process in which 2 lightweight atomic nuclei combine to form a heavier nucleus, releasing a large amount of energy
holds huge potential
amount of energy that would be released by combining the deuterium (H2) in 1 cubic kilometer of ocean water would be greater than that contained in world’s entire supply of fossil fuels
problems
three conditions must be met simultaneously
adequate density
high temperature
if heat is used to provide energy necessary for fusion, temperature must approach that of center of sun
walls of vessel containing atoms would have to be able to resist that heat