Nuclear Energy Essay, Research Paper

Nuclear Energy

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.