Essay/Term paper: Nuclear energy

Essay, term paper, research paper:  Science

Nuclear energy by definition is the energy
consumed or produced in modifying the
composition of the atomic nucleus. Nuclear energy
is used for things such as atomic bombs, hydrogen
bombs and other nuclear weapons. Nuclear
energy can also be used for powering
electricity-generating plants all over the world.
There are many arguments for and against nuclear
power. Nuclear power is an inexpensive clean
source of power. Others feel that because of the
hazardous radiation emitted during the producing
of the power and the radioactivity of the material
used that nuclear power is not as good as the
alternatives which are fossil fuels and solar
power.(Hansen, 1993)

If matter changes state or composition, it is
accompanied by the production of energy.
Processes such as combustion produce energy by
rearranging the atoms or molecules of that
substance.(Brain, 1998) An example of this is the
combustion of methane (natural gas)

CH(4) + 2O(2) = CO(2) + 2H(2)O + energy

In this example the amount of energy released is
eight electron volts or 8 eV. The electron volt unit
is the unit used by nuclear physicists. The electron
volt represents the gain in kinetic energy when an
electron is accelerated through a potential drop of
one volt.(Brain, 1998)

The most common nuclear reaction is nuclear
fission. Nuclear fission is the process in which a
heavy nucleus combines with a neutron and
separates the heavy nucleus into two lighter
nuclei.(Roy, 1993) The most typical fission
reaction is that of uranium-235 it is as follows:

92 U235 + 1 neutron = 38 Sr96 + 54 XE138 + 2
neutrons + energy

Another type of nuclear reaction is nuclear fusion.
Nuclear fusion occurs when two light elements
combine to form a heavier atom.(Grisham, 1993)
An example of this is:

1 H(2) + 1 H(3) = 2 He(4) +1 neutron + energy



Nuclear Fission

Nuclear fission is a complex process, but many
products are formed during this process. Not only
the two nuclei but also neutrons, beta particles,
neutrinos and gamma rays are created during the
fission process.(Roy, 1993) There are more than
fifty different ways a nucleus may undergo fission.
Some of the ways are much more common than
others. During the fission process the nucleus
breaks into to unequal parts, one lighter fragment
and a heavier fragment. These nuclei are formed
with excess energy that they do not usually have in
their ground state they must lose the extra energy.
They release this extra energy in the form of
gamma radiation or sometimes neutron emission.
The primary fragments are rich in neutrons and are
radioactive. Uranium-235 which contains 92
protons and 143 neutrons are more likely to under
go fission when bombarded by low-energy
neutrons.(Hansen, 1993)



Nuclear Fission Used in Bombs

The fission process was discovered in the late
1930s. In late 1939 two scientists Otto Frisch and
Lise Meitner discovered the fissioning of uranium
into lighter particles while they were doing an
experiment involving neutron irradiation of
uranium. The possibility of a self-sustaining chain
reaction was apparent this caused an accelerated
rate of research.(Hansen, 1993)

The United States Government researched into the
possible applications of nuclear fission at the
beginning of World War II. In order for the
weapon to be able to work properly it would
require a self-sustaining fission reaction to be
created and also that an adequate amount of
fissionable material could be produced for use in a
weapon.(Brain, 1998) On December 2, 1942 at
the University of Chicago Enrico Fermi and his
team developed the worlds first self-sustaining
reactors. The reactor was fueled with natural
uranium imbedded in graphite blocks.(Hansen,
1993) The fission occurred in the isotope of
uranium, U-235. An important factor in
developing the nuclear bomb was to separate
U-235 from U-238. Natural uranium only contains
0.7% of U-235 and the remaining 99.3% of
natural uranium is U-238. The problem with this is
that U-238 does not fission except with very high
energy neutrons which are not available from the
fission process. To separate the two materials
gaseous defusion is used. Another way of making
nuclear weapons is to use a different fissionable
nucleus. Another material that is used is a synthetic
isotope of plutonium P-239.



Nuclear Fusion

In most fusion reactions after the two atomic nuclei
merge together to form a heavier nucleus a free
nucleon is also formed. In just about all fusion
reactions between light nuclei, a portion of their
rest mass is converted into kinetic energy of the
reaction products, or into gamma rays.(Grisham,
1993) The kinetic energy and gamma rays that are
released in the process of fusion, heat the inside
keeping the temperature very high so the fusion
can continue occurring. At thermonuclear
temperatures, matter can only exist in the plasma
state. Matter at thermonuclear temperature
consists of electrons, positive ions and very few
neutral atoms. If fusion reactions occur within
plasma the reactions heat the substance even
more, because a portion of the reaction energy is
transferred to the bulk of the plasma through
collisions.(Grisham, 1993)

Stars produce their energy through many types of
fusion reactions. Scientists know that fusion
reactions have clear potential as a power source
on earth due to the fact those fusion reactions have
been driving the stars for billions of years.(Hansen,
1993) For many decades now scientists have tried
to develop thermonuclear fusion reactions that will
produce useful power.



Nuclear Waste

Nuclear waste is one the biggest down fall to
nuclear power. Nuclear waste is any radioactive
material that is created by nuclear
technology.(www.hydro.on.ca, 1999) The most
common form of nuclear waste is those that are
produced by civilian nuclear industry and the
nuclear weapons program.

There are many other sources of nuclear waste to
some of them are radioactive material that is
produced by medical research, research on
nuclear power, industrial applications and the
contaminated sections of dismantled nuclear
facilities. Radioactive material decays by different
forms of radiation. Two different forms of
radiation are gamma rays and alpha particles. The
decay of the nuclear waste is characterized by the
type of emission, the energy of the emitted
radiation, and the rate at which decay occurs. The
decay rate of a radioactive material is usually
measured in terms of the half-life. A half-life is the
time that is required for one-half of the radioactive
material to decay.(Brain, 1998) The half-life of
each radioactive material is different, a half-life can
range from less than a millionth of a second to
billions of years.

The danger of radioactive material is that the
emitted radiation may come in contact with the
human body and cause damage to cells. The
effects of exposure to radioactive material can
vary from mild, which is temporary illness to
death. The effects of exposure can occur
immediately or can be delayed depending upon
the amount of radiation received.(Hansen, 1993)

There are many different types of nuclear waste.
Nuclear waste is normally characterized by it
physical and chemical properties and also their
source of origin. For example is the United States
all waste from the nuclear defense program is
classed as military waste and is usually treated
separately.



Chernobyl

Chernobyl is a Soviet Union nuclear power plant
that is located about 130 km north of Kiev in
Ukraine. At the Chernobyl nuclear power plant
occurred the world"s worst nuclear-reactor
disaster on April 26, 1986. On this day the power
plants number 4 reactors exploded. The accident
occurred while an experiment was being
conducted with the graphite-moderated reactor
running but its emergency water-cooling system
turned off. The nuclear reactor suddenly went out
of control because of some miscalculations
allowed a neutron build-up in the core. The power
surge shattered the fuel. A steam-induced
explosion blew the lid off of the reactor because
the reactor was not designed for such pressure.
Another chemical explosion followed and
scattered fragments around the plant causing local
fires.(Grolier, 1993)

This nuclear killed 31 persons either immediately
or shortly thereafter, the nuclear blast also caused
the hospitalization of 500 others. People living
within 30 km of the power plant were evacuated
within a few days of the blast. Much of the
radioactivity was carried away from the site at high
altitudes due to the explosions and the fire.(Brain,
1998) The radioactivity was spread across the
Northern Hemisphere. The heaviest of the
radioactivity descended upon western Soviet
Union and some of Europe. These areas took
preventive steps to protect their food supplies.
The data on the effects of the radioactivity on the
world remain inconclusive.

The area within 30 km of the power plants
removed the heavily contaminated soil and trees to
try and get rid of any nuclear waste left there. In
1990 the authorities acknowledged that several
million people were still living on contaminated
ground. Illnesses such as thyroid cancer, leukemia
and other radiation illnesses are much higher than
normal among these people living on contaminated
ground. At the plant reactor number 4 was
entombed in concrete. Two of the three reactors
at Chernobyl are still in operation. There have
been other accidents since reactor number 4 blew
up because of this Ukraine"s Parliament in 1991
pressed for a complete shut down of the plant.
This idea is highly unlikely because it is the only
power source for the region.(Hansen, 1993)



Nuclear Energy Today

Nuclear power has become a major source of the
world"s electric energy since the discovery of
fission 50 years ago. At the end of 1989 there
were 416 nuclear power plants operating
worldwide producing 17% of the world"s
electricity. There were 130 plants that were under
design at the end of 1989. Nuclear power is used
in 27 different nations and another three nations
have plants under construction. The United States
has the world"s largest nuclear energy program at
the end of 1989 with 108 operating plants having
the operating capacity of 100,000 MW providing
20% of the U.S. with their power. In 1989 nuclear
power was the second largest source of electricity
in the U.S. exceeded only by coal which
contributes 55% of the U.S."s electricity. Other
sources of power are natural gas 9%, oil 6%, and
hydro power 9%.(Hansen, 1993) In Ontario 40%
of the electricity that is used is produced by
nuclear power. Ontario nuclear power plants
produce 8728 MW of
electricity.(www.hydro.on.ca, 1999)

Nuclear power plants are more complex and cost
more to build than plants that use fossil fuels. The
cost of fuel for nuclear power is much lower than
the cost of fossil fuel. In the long run nuclear
electricity is much cheaper for most nations
because of the differences in fuel prices. For
industrialized countries of Europe and Asia the
difference in cost may be as large as a factor of
half the cost. In some countries the nuclear power
program has come to a standstill. In the United
States there hasn"t been an order to build a
nuclear power plant since mid-1970's. The main
reason for the standstill is the move towards
increased efficiency in the consumption of oil and
also a drop in the demand for energy. The public
is also concerned about the safety of nuclear
power plants and also the increasing awareness of
the problems with nuclear waste. The reason for
the increase in safety awareness is because of the
accidents that have occurred. Before 1979 the
public was all for nuclear energy but since then a
reactor in Three Mile Island leaked radioactive
material into the environment. The largest reason
why the public changed their view was the
explosion of reactor four at the Chernobyl power
plant.

Nuclear power is an important factor in all of are
lives, if it if used safely it provides us with
inexpensive electricity but if used carelessly it can
make us ill, destroy the land and even kill us. It is
believed that in the future nuclear power will be
safer for all. The pro and cons of nuclear power
are balanced because it is much more inexpensive
and it will not run out like fossil fuels eventually
will. Nuclear reactors do not explode all that
often.