8. Example of a project

Below find an example of an actual student project in two formats
which can be used as a model for you:

For a web presentation of the project click here
For a regular (word 'doc' ) presentation click here

 

The Use of Nuclear Energy in Europe

Northern Helsinki Upper Secondary School

Sarah-Maria de la Rosa Zorita
Valeri Luzik
Jussi Laine

The first nuclear power plants
Operating principles
Why nuclear energy?
The pros and cons
The manufacturing of nuclear fuel
Nuclear waste
The final disposal of nuclear waste
The effects of radiation
A nuclear disaster
References

 

The first nuclear power plants

The first commercial nuclear power plants were introduced in Europe in the 1950s and the 1960s when the risks and dangers involved in the use of nuclear energy were not known (today there are more than 120 nuclear power plants in Europe). Nuclear energy was idealized until the late 60s when we started to realize the disadvantages of nuclear energy which had so far been underestimated or hushed up. Despite the drawbacks the construction of nuclear power plants has not stopped because nuclear energy is cheap and readily available in large quantities and it doesn't pollute like fossil fuels do.

- top -

Operating principles

The most common types of reactor used in nuclear power plants are pressurised-water reactor and boiling water reactor. Their operating principles are really complicated. The reactors of a nuclear power plant use uranium and plutonium as their fuel. One fuel rod gives as much energy as 78 tons of coal. It doesn't burn by combining with oxygen, like most fuels, but the heat is produced when the nuclei of atoms are split in a chain reaction. The resulting product of combustion consists of isotopes of the uranium fuel, most of which are radiant. The emerging heat radiates into water which vaporizes and is transferred via tubes into a condenser making turbines turn on the way. A generator then converts their rotational energy into electricity. This is the operating principle in a nutshell.

- top -

Why nuclear energy?

Why are nuclear power plants used even though they constitute a threat to the whole society? In Europe, for example, Germany has the largest number of nuclear power plants, which, in addition, are situated all over the country. This is rather like living near an active volcano and never knowing when it will erupt. Why do we make such wide-spread use of nuclear energy?

Why do many people who favor nuclear power plants make claims about the purity of nuclear energy when all the while they are aware of the fact that money and cheap fuel were the most important factors, and not the risks involved in the use of nuclear energy. While coal fueled power stations pollute more aggravating the greenhouse effect, at least they do not cause genetic mutations, which can be the result of a nuclear disaster of the failed further processing of nuclear waste. Although they oppose nuclear energy, it is doubtful whether people would be willing to double their electricity bills just to get electricity not produced in a nuclear power plant. We believe that people's views of nuclear power plants will change as soon as we find a way to render nuclear waste harmless. But before that nuclear power plants will be eyed skeptically and critically.

- top -

The pros and cons

One of the undebatable advantages of nuclear energy is that it does not increase the amount of greenhouse gases. The amount of nuclear waste is relatively small, it does not spread, and nuclear power is reasonably cheap. There are also disadvantages. The danger of radiation can be caused by an accident in a uranium mine, in a uranium enriching plant, in the transport and storage of fuel, in nuclear weapons industry, in the handling and storage of nuclear waste, in a nuclear-powered boat or submarine, in the crash of a nuclear-powered satellite, and in a hospital or research facility using radioactive matter. The greatest risks occur in mining, nuclear power plants and reprocessing.

Nuclear power plants are a great risk; even the smallest mistake in the complicated systems of a nuclear power plant can result in a disaster. The worst accident took place in the former Soviet Union, today's Ukraine, in Tchernobyl, in 1986. In the nuclear power plant there were four reactors, one of which was due to be shut down for its periodic maintenance. Before that they decided to test how long the slowing generator could produce electricity. The test ended in tremendous explosions which broke the reactor, lit a graphite fire and melted the fuel rods. Radiation escaped into the surrounding area through the broken roof for ten days. The consequences were disastrous. The worst fallout was suffered by the immediate surroundings of the nuclear power plant, but evacuation procedures were not begun there until after 36 hours had elapsed. A total of 135,000 people were evacuated from an area with the radius of 30 km. The area will be unfit for living for decades to come. The radiation escaping from the nuclear power plant killed hundreds of people and thousands were exposed to extra large doses of the dangerous radiation.

The nuclear disaster at Tchernobyl opened many people's eyes and after the catastrophe anti-nuclear groups emerged in many countries, demanding the closing down of nuclear power plants. The issue worried governments, too, which resulted in a tremendous increase in the number of back-up systems in nuclear power plants, and the careful selection of staff.

- top -

The manufacturing of nuclear fuel

First, uranium ore is quarried in a uranium mine. The supply is not likely to run short at the present rate of use. From there, uranium is sent on to be enriched in an enriching plant. The enriched uranium is transported into a fuel plant where it is turned into uranium oxide ultimately to be packed in fuel rods. The rods are taken into a nuclear power plant where they are placed in a reactor. After having been used they are replaced with new ones. The used fuel, which has become extremely radioactive, is taken in special containers into a reprocessing plant. The usable raw materials are separated from the waste there and the rest is placed in storage to wait for final disposal.

- top -

Nuclear Waste

The used fuel removed from nuclear reactors is called high activity waste. The nuclear process also produces less active forms of waste, so-called power plant waste. A corresponding form of waste will also be the result when nuclear power plants are dismantled in the future. Nuclear waste is divided into low, middle, and high level of activity depending on the level of radiation in the waste and the danger it presents.

Low activity waste can be handled without radiation shielding. It contains radioactive substances which, when introduced in the human body eg through the process of respiration, can result in considerable doses of radiation. Therefore low activity waste must be isolated from nature for a period of 50 to 100 years.

Middle activity waste has such high levels of radiation that, for security reasons, it must be handled with remote-controlled equipment or using radiation shielding. The active matter content is approximately ten times that of low activity waste.

Owing to the high level of radiation in the high activity waste the fuel can only be used once, or after use the waste is recycled. Both alternatives produce high activity nuclear waste which must be placed somewhere with special precautions and isolated carefully enough from nature.

At first, the fuel which is removed from the reactors of nuclear power plants has extremely high levels of radiation. Even though the activity concentration of the used nuclear fuel ultimately decreases very fast, it remains highly dangerous for a very long time. Such high activity waste should under no circumstances have contact with living organisms and it must definitely be contained for hundreds of thousands of years.

Now that nuclear power plants have been in use for almost 50 years, we have accumulated roughly 150,000 tons of radioactive uranium refuse the radioactivity of which is 1,000,000 petabecquerels (PBq, 1 PBq = 1,015 Bq). Only a third of this amount has been reprocessed.

- top -

The final disposal of nuclear waste

The countries using nuclear energy have spent a lot of resources on nuclear waste disposal in the last couple of decades. In the disposal of middle and low activity waste many countries such as Sweden, Germany, France, and Spain have reached the final disposal stage.

The final disposal of nuclear refuse in the ground or bedrock is necessary in all the present-day types of reprocessing. Nowadays the preparations are focused on the disposal of high activity waste. The plans for nuclear waste disposal have been delayed in many countries because of political or public resistance. In some countries the instances responsible for nuclear waste disposal have been loosely defined, which has made decision-making difficult. All the countries have not been prepared for the cost of nuclear waste disposal. This subject brings forth mixed opinions all over the world.

Sweden and Finland are among the pioneers in nuclear waste disposal. In the areas surrounding Finland there is a lot of nuclear waste in temporary storage. The world has accumulated a total amount of used nuclear fuel corresponding to over 150,000 tons of uranium, two thirds of which have not yet been either finally disposed of or reprocessed.

In her nuclear refuse policy Sweden relies on independent decisions and her own expertise. Nuclear waste is processed and disposed of within Sweden's own borders; Sweden neither exports nor receives nuclear refuse. Swedes, too, aim at finding a suitable location for final disposal in the hard rock, the similar kind of bedrock that Finland has. Sweden started research and development on the final disposal of nuclear waste in bedrock as early as in the late 1970s. The intended date of final disposal is around the year 2010.

In France the processing of used fuel has been developed quite far. The country also has a research program on final disposal. In the first stage, France is going to excavate laboratories in the bedrock and three towns have been selected as potential localities for them. Laboratories will be built in the bedrock of at least two or all three of the selected areas. Later, one of these will be named the location for final disposal. France aims at beginning final disposal around the year 2010.

In Germany, used fuel and high activity nuclear waste are going to be placed in facilities which will be built in the Gorleben salt bed. Exploratory shafts and tunnels have already been drilled in the area. Germany strives to begin the actual final disposal in 2008. There already exists an intermediate storage for used fuel in the area and the transporting of fuel into it has brought forth considerable opposition in Germany. An experimental facility for enclosing used fuel in capsules is also about to be finished in Gorleben.

The disposal of used fuel in Britain is based on reprocessing. In Sellafield there is a reprocessing plant for used fuel. At the moment there are no plans for the final disposal of the resulting high activity waste in Britain, i.e. the preparations have not begun.

In Switzerland the disposal of used fuel is based on reprocessing. They have long researched the final disposal of both low, middle and high activity nuclear waste. The aim of the Swiss is to be able to begin final disposal in 2020 at the earliest.

Estonia has her work cut out for her in cleaning the nuclear facilities left behind by the former Soviet Union. In Paldisk they are clearing out the military base, Tammiku houses the burial ground of radioactive waste, and the town of Sillamäe strives to take care of mining refuse containing uranium.

Russia has plenty of experience in treating nuclear waste, but compared internationally, several shortcomings are seen in her present-day disposal systems. The preparations for final disposal have not progressed far. Russia's most important storage and processing facility for used nuclear fuel is located in Majak in the Ural region, which is where the used fuel from the Loviisa nuclear power plant was transported before. Russians are planning to transfer nuclear waste into containers made from steel and concrete. This dry container storage facility is meant to be put into use around the year 2000.

- top -

The effects of radiation

Ionizing radiation can damage the genotype of living cells, but from the point of view of the cell damage it makes no difference whether it is caused by artificial or natural radiation. What counts is the length of the period of exposure to a dose of radiation. Even a small dose increases the risk of developing cancer and a large dose in a short period of time can destroy cells on a large scale, and even cause radiation sickness, local injury or foetal injury.

During pregnancy unnecessary exposure to radiation must be avoided. The primary reason is, however, not the risk of developmental disorders since small doses of radiation do not increase the number of deformations. Exposure to radiation at a very early stage, even before the pregnancy is known, can result in an early miscarriage. If the pregnancy continues regardless of the exposure the child will, in all likelihood, be completely healthy. On the other hand, a foetus exposed to radiation during pregnancy runs a greater risk of developing cancer later. If the foetus is exposed to a large and sudden dose of radiation at a sensitive stage (eg the mother receives radiotherapy during pregnancy), it is possible that the child will have a small head, be small in terms of size, or even mentally retarded. In addition to these, other developmental disorders have not been observed until after massive doses.

- top -

A nuclear disaster

A radiation alert is given by means of a universal alarm signal if a radioactive leak has occurred. Everyone should know how to protect themselves from radiation if one hears a radiation warning or a radiation alert.
PROTECTING ONESELF FROM RADIATION:
Get inside quickly. The more walls you have around you the better you are protected, thus an air-raid shelter is best. If going outside is absolutely necessary, you must wear clothing which covers the skin, fits snugly, and is easily cleaned. A respirator, a towel, or a paper towel helps prevent radioactive particles from entering the respiratory organs, ie lungs, when one breathes.

Windows and doors must be kept tightly closed and air conditioning must be kept off. Listen to instructions on the radio and do not call the authorities to inquire about the situation as it will block telephone lines which will make rescuing even harder. Cover food (Put foodstuffs in plastic bags or tightly sealed containers such as the fridge or the freezer. Canned food is protected well enough as it is.) and drinking water. Leave the area of the fallout if you are instructed to do so. Do not take iodine tablets unless the authorities advise you to do so.

- top -

References

Books:
Koulun maantieto Riskien ja mahdollisuuksien maailma (School geography The world of risks and possibilities)
Tieteen maailma Tiede ja yhteiskunta; Energia ja liikenne (The world of science Science and Society; Energy and Transport)
Energia (Energy)

The Internet:
http://www.tvo.fi/faq.htm
http://www.stuk.fi/ydinvoimalaitokset/
http://www.dystopia.fi/~jaker/ydinpommi/index.htm
http://norssi.oulu.fi/~vpjokin/energia.htm#Ydinenergia
http://members.tripod.com/~jkauppila/energia.htm
http://www.posiva.fi/ls_yh1.html

- top -


Translated by Elina Hyttinen, M.A.
English Teacher
Upper Secondary School
Northern Helsinki

Back to the beginning of this page