To complete the following research assignment about radiation, you must download the file Chuck Radiation.doc. Just in case you are having problems downloading this file, I cut and pasted it on this page, but the pictures didn't copy, just the text.  Please try to download this file because it is much prettier with the pictures.  The criteria for this assignment is at the bottom of this article.  Now don't cheat and look at the assignment criteria at the end of this article until you read the file. I know, it's hard to resist.  You can do it.  Wait for the good news at the end.
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WHAT IS RADIATION?
Radiation is energy. It travels through space in the form of particles or waves. Radiation is energy such as heat, light, sound, microwaves used to cook food   radio waves, X-rays for diagnostic medical purposes and radar.
Radiation can be in the form of high speed alpha particles and beta particles emitted by heavy metals such as uranium and radium, and neutrons produced at fission.
RADIATION IS EVERYWHERE
It is in the air we breathe, the water we drink, and the food we eat. This makes up the "background radiation" that we are all exposed to everyday. Background radiation, from space or even food, contributes to at least 3 mSv  (unit of measurement) per year per person.Main sources of natural radiation are the following:
·       Radioactive substances in the earth's crust
·       Radioactive gas (radon) from the earth that is released naturally from traces of uranium in soil and rock
·       Cosmic rays from outer space which bombard the earth
·       Trace (very tiny) amounts of radioactivity in the body

RADIATION AND RADIOACTIVITY
Substances are said to be “radioactive” when they emit radiation, either naturally or as a man-made condition. In Canada, on average, approximately 85 percent of human exposure to radiation is from natural sources. These include radon gas from the earth's crust that is present in the air we breathe, terrestrial radiation from mineral soils, and cosmic radiation from space. Our bodies are also a source of radiation from potassium and carbon in the foods we eat. The remaining sources of radiation exposure are manmade. Fourteen percent comes from medical technologies including x-rays and gamma-rays. And one percent can be categorized as “other” – created by things like the nuclear generation of electricity.
                      
WHAT CAUSES ATOMS TO BE RADIOACTIVE?
Atoms found in nature are either stable or unstable. An atom is stable if the forces among the particles that make up the nucleus are balanced. An atom is unstable (radioactive) if these forces are unbalanced--if the nucleus has an excess of internal energy. Unstable atoms are called radionuclides. The instability of a radionuclide's nucleus may result from an excess of either neutrons or protons. An unstable nucleus will continually vibrate and contort and, sooner or later, attempt to reach stability by some combination of means:
·       ejecting neutrons, and protons
·       converting one to the other with the ejection of a beta particle or positron
·       the release of additional energy by photon (i.e., gamma ray) emission.
                    
HOW LONG DO RADIONUCLIDES STAY ACTIVE?
It depends on the kind of radioactive material you're dealing with. The rate of decay is one of the characteristics of radionuclides. Scientists talk about this rate as a radionuclide's radioactive half-life, commonly referred to as just half-life. The half-life of an element is the amount of time it takes for half of the atoms to decay.  The half-life of an isotope is always the same.  Because decay happens the most when there are a lot of atoms, when there aren't as many atoms left, things slow down.
 
“NON-IONISING” RADIATION
Non-ionizing radiation does not have enough energy to cause atomic changes.
 
​IONISING RADIATION
Energy released from radioactive atoms is 'ionising radiation'. This is because when a non-radioactive atom is hit by radiation, it gives up one electron, and is said to be 'ionised'. These electrically charged particles are called ions.
The forms of ionizing radiation are alpha particles, beta particles and neutrons, as well as x and gamma-rays. Ionising radiation is also released by nuclear fission

TYPES OF IONISING RADIATION: ALPHA, BETA AND GAMMA
Alpha particles are very heavy and lose their energy quickly. They are positively charged, and are also quite large, and therefore cannot travel very far, or pass through matter such as a piece of paper or human skin. However, care should be taken not to swallow or inhale anything likely to emit alpha particles, as they can cause damage to body organs.
Examples of some alpha emitters: radium, radon (radioactive gas),  uranium, thorium.
Beta particles are small (and negatively charged). They are fast moving and can travel further than alpha particles. They can penetrate up to 1 - 2 centimetres of matter such as human skin.
Examples of some pure beta emitters: strontium-90, carbon-14, tritium, and sulfur-35.
Gamma rays and X radiation are high-energy waves, similar to light, but have much higher energy, and can travel very long distances. However, matter such as concrete, lead or metal, or even water can stop them in their tracks.
 
Examples of some gamma emitters: iodine-131, cesium-137, cobalt-60, radium-226, and technetium-99m.
Neutron radiation is also encountered in nuclear power plants and high-altitude flight and emitted from some industrial radioactive sources.

WHAT IS NUCLEAR FISSION? 
Ionising radiation is released by nuclear fission.  Fission is the process of splitting apart of a parent cell or atom. In nuclear fission, heavy atoms like uranium or plutonium are split apart by a single neutron to form lighter elements and release energy.
 
Uranium decays naturally but can be forced into nuclear fission by using a nuclear reactor. Inside the reactor several uranium atoms are split apart to generate lighter elements and heat.
 
Out of all of the uranium in world, only special uranium is used for nuclear fission, which is processed U-235. It is often used for nuclear fission because the nuclei of that isotope can break apart easily. If there is no U-235, the power plant operators use a special plutonium isotope instead

HOW DOES NUCLEAR FISSION HAPPEN IN A NUCLEAR REACTOR?
 
The U-235 is first processed before it can be used in nuclear fission. Once the special U-235 is loaded into the reactor, nuclear fission begins when a neutron is fired into a U-235 nucleus. Nuclear fission releases energy.
The splitting of an atom into two smaller atoms, creates heat and sends neutrons flying. If another atom absorbs one of those neutrons, the atom becomes unstable and undergoes fission itself, releasing more heat and more neutrons. The chain reaction becomes self-sustaining,
producing a steady supply of heat to boil water, drive steam turbines and thereby generate electricity.

The temperature of the nuclear reaction is controlled by a series of control rods. These rods can also be used to stop the reaction completely in case of a U-235 reload, an accident, or a malfunction.

NUCLEAR POWER PLANT SAFETYThere are a number of safety precautions in place. Numerous drills like the fire drills we have at school are performed to practice the emergency plan. The control rods can be placed fully into the reactor to stop the reaction completely if the operators suspect that there is something wrong. The concrete walls are three to six feet thick to prevent any radiation from escaping. There are armed personnel to protect the plant from sabotage. Nuclear waste is either stored in pits resembling swimming pools or specially designed steel cases. Nuclear waste is either stored in the plant itself or in nuclear waste disposal facilities.

In Japan, the March 11th earthquake and tsunami caused blackouts that cut off the externally sourced AC power for the reactors' cooling system. According to published reports, backup diesel generators at the power plant failed shortly thereafter, leaving the reactors uncooled and in serious danger of overheating.  Even after the control rods have done their job and stopped the fission reaction the fuel rods retain a great deal of heat. What is more, the uranium atoms that have already split in two produce radioactive by-products that themselves give off a great deal of heat. So the reactor core continues to produce heat in the absence of fissioning.  Without a steady coolant supply, a hot reactor core will continuously boil off the water surrounding it until the fuel is no longer immersed. If fuel rods remain uncovered, they may begin to melt, and hot, radioactive fuel can pool at the bottom of the vessel containing the reactor. In a worst-case meltdown scenario the puddle of hot fuel could melt through the steel containment vessel and through subsequent barriers meant to contain the nuclear material, exposing massive quantities of radioactivity to the outside world.
                                                                                               
EFFECTS OF RADIATION ON OUR BODY CELLS 
Biological effect begins with the ionization of atoms. The mechanism by which radiation causes damage to human tissue, or any other material, is by ionization of atoms in the cell material.
Ionizing radiation absorbed by human tissue has enough energy to remove electrons from the atoms that make up molecules of the tissue.
When the electron that was shared by the two atoms to form a molecular bond is dislodged by ionizing radiation, the bond is broken and thus, the molecule falls apart. This is a basic model for understanding radiation damage.
When ionizing radiation interacts with cells, it may or may not strike a critical part of the cell. We consider the chromosomes to be the most critical part of the cell since they contain the genetic information and instructions required for the cell to perform its function and to make copies of itself for reproduction purposes.
 
The following are possible effects of radiation on cells:
Cells are undamaged by the dose
Ionization may form chemically active substances which in some cases alter the structure of the cells. These alterations may be the same as those changes that occur naturally in the cell and may have no negative effect.

Cells are damaged, repair the damage and operate normally
Some ionizing events produce substances not normally found in the cell. These can lead to a breakdown of the cell structure and its parts. Cells can repair the damage if it is limited. Even damage to the chromosomes is usually repaired. Many thousands of chromosome changes occur constantly in our bodies. Our body can repair these changes.

Cells are damaged, repair the damage and operate abnormally
If a damaged cell needs to perform a function before it has had time to repair itself, it will either be unable to perform the repair function or perform the function incorrectly or incompletely. The result may be cells that cannot perform their normal functions or that now are damaging to other cells. These altered cells may be unable to reproduce themselves or may reproduce at an uncontrolled rate. Such cells can be the underlying causes of cancers.
 
Cells die as a result of the damage
If a cell is really damaged by radiation, or damaged in such a way that reproduction is affected, the cell may die. Radiation damage to cells may depend on how sensitive the cells are to radiation.

All cells are not equally sensitive to radiation damage. In general, cells which divide rapidly and/or are relatively non-specialized tend to show effects at lower doses of radiation then those which are less rapidly dividing and more specialized. Examples of the more sensitive cells are those which produce blood. This system (called the hemopoietic system) is the most sensitive biological indicator of radiation exposure.
A chronic dose is a relatively small amount of radiation received over a long period of time. The body is better equipped to tolerate a chronic dose than an acute dose. The body has time to repair damage because a smaller percentage of the cells need repair at any given time. The body also has time to replace dead or non-functioning cells with new, healthy cells. This is the type of dose received as occupational exposure.
The biological effects of high levels of radiation exposure are fairly well known.  These effects include some forms of cancer and genetic effects.
 
​Electricity from Nuclear Fuel
Nuclear technology uses the energy released by splitting the atoms of certain elements. It was first developed in the 1940s, and during the Second World War research focused on producing bombs by splitting the atoms of either uranium or plutonium.
There are now over 440 commercial nuclear power reactors operating in 30 countries around the world.
 
They provide about 14% of the world's electricity and their efficiency is increasing. Fifty-six countries operate a total of about 250 research reactors and a further 180 nuclear reactors power some 140 ships and submarines. 
 

WHAT DO YOU THINK?  
What are the advantages and drawbacks to using nuclear fuel to generate electricity?  Should countries continue to construct nuclear reactors?  Why or why not?
Write a 250- 500 word essay explaining your position.  This essay must be double space and word processed.  Your essay must include:

• An introductory paragraph

• Write about two advantages and two drawbacks

• Five points to support your opinion whether countries should or should not continue to generate electricity using nuclear reactors You must back up your points with evidence from reputable sources.

• A concluding paragraph

• Attach a bibliography containing a minimum of four sources. (remember the VPL website)

You will have to conduct your own research to help present your opinion.  Use real life examples whenever possible.