Roche A. Samy
RADIOACTIVITY:
Objective After this activity, the students will be able to explain and describe:
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1) What radiation is;
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2) What are the effects of radiation to biological organisms;
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3) The sources and effects of radioactive pollution from commercial power plants;
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4) The radioactive pollution from nuclear weapons production;
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5) Radioactive pollution from nuclear warfare.
Activity One of the simplest methods to detect radiation is the DIGI-CHECK Thermo foil. It is an extremely sensitive liquid crystal that reacts to minimal temperature fluctuations. It is based on scientific insight acquired during research into thermography, during early detection of breast cancer. The thermographic micro-Encapsulated Cholesteric Liquid Crystals (ECLC), disclose by discoloring indicating the presence of malignant tumor.
The blood circulation at your finger tips is controlled by emotional stress, smoking, radiation and other physiological conditions. You can detect your thermal radiation by pressing your thumb on the foil of the plastic DIGI-CHECK for ten seconds. Your immediate level of blood circulation and your emotional condition will be represented by the color of the foil.
In an activated state, the crystals are dark colored. The color ranges from dark-brown to red, green, and blue the last color signifies that you are relaxed and have good circulation. If you have been smoking or very tired, the color would be dark-brown, showing the stressed and crucial condition.
The DIGI-CHECK is very inexpensive and can be obtained from Progressive Enterprises, 145, Elmdale Road, Canterbury, Connecticut 06331. An illustration of the DIGI-CHECK is
Discussion:
Radioactive Effects on Biological Organisms:
Radioactive substances emit either nuclear particles which consist of alpha or beta particles or pure energy radiation like X-rays and Y-rays (gamma rays). These energetic waves cause damage to human tissue when exposed. While travelling through the tissues, these rays rip electrons from the molecules and atoms. This phenomenon leaves the atom and molecules “ionized” or charged electrically. These ionized particles and the ejected electrons can cause death or damage to cells and cell components.
The severity and type of damage depends on what and where the waves strike, the amount of radiation, the exposure time, and the sensitivity of the struck cell.
In living things, (animals and plants), cells form organs, organs form systems and systems comprise the whole body. Radiation damages or kills cells. If most of the cells die, the organ which is made up of these cells will die. (lung, liver, kidney, brain, mammary gland(breast) etc.) If the important organs die (ex. heart, lungs, brain etc) the system dies and the whole organism dies. So it is evident to note that the ultimate consequence of radiation is
death
.
Radiation is measured in
rems.
The lethal dose of radiation when exposed to the whole body is in excess of 1000 rems over a brief period(minutes or hours as it happened in
Hiroshima
and
Nagasaki
, bombings. Even a dose of 500 rems will cause death, if delivered to the whole body at one time., at least in 50% of the cases. Below 500 rems to 100 rems, radiation sickness occurs and some patients will die eventually. At radiations below lOO the effects and consequences are very difficult to detect or predict. In most lower radiation exposures it is mostly cell damage and not cell death. But the damaged cells may replicate and multiply causing complications. It also depends on the sensitivity of the cell. In an ordinary cell tissue like flesh or bone, the damage caused is called “somatic” damage. The most feared somatic damage is the blood cancer or leukemia. If the reproductive cell (testes, sperm, ovum etc.) is damaged, then
mutation
can be caused and this damage is passed on to future generations. Even doses of one rem can cause mutations depending on the latency period and the time between exposure and effect is long.
Radiation Pollution from Commercial Plants:
Nuclear power plants use uranium 235 fuel in the reactor where it fissions and generates heat which is used to produce electricity. The fission products gradually accumulate and thereby affect the chain reaction. The
spent fuel
is then removed and stored under water in large pools near the reactor site.
Other types of radioactive wastes from nuclear reactors are fission product gases (krypton, xenon), filter media left over from treating contaminated cooling and cleaning water, other solid wastes like cleaning paper and protective clothing.
The most serious, health hazard from nuclear wastes is the
uranium mill tailings.
These mill tailings are residues obtained when uranium ore is crushed, ground and chemically processed to produce a compound U308 known as “
yellow cake
”. This operation releases small amounts of radon gas and uranium dust. During the refining process the finely ground tailings are suspended in water. The water gradually seeps and evaporates leaving a dry pile containing radium which decays into radon and other isotopes. The yellow cake conversion produces sludge and other wastes which includes some gas, but mainly radium, some uranium and thorium.
Every one must be aware of the “Three Mile Island” accident, on March 28, 1979, that should not have happened. Human errors, leaks, management problems, proper training and safety valves should be taken care of so that such accidents do not happen in the future. The Chernobyl accident in Russia that happened in 1986 is the worst kind that has ever happened in human history.
Radiation Pollution from Nuclear Weapon Production:
Radioactive wastes from military-related operations producing weapon materials such as tritium and plutonium do also concern many environmentalists. These types of plants have been in operation for more than thirty years. Most of the high-level radioactive wastes are produced as nitric acid solutions of fission products and transuranics.
To store these wastes, large stainless steel tanks are needed. To simplify this costly, storage problems, first they have to be neutralized with sodium hydroxide to permit storage in ordinary steel tanks. Secondly, the dissolved radioactive materials are precipitated and the water was evaporated from the liquid mixtures to reduce the storage volume. As a result of these operations high level radioactive wastes which are in storage now are composed of damp crystallized salt, sludge, and other solutions with a total volume of twenty million gallons.
In operations where there is low level radioactive wastes, contaminated equipment, hardware like valves, pipes, reactor fittings, tanks, pumps, contaminated oil, mercury, cloth, papers and plastics, are buried in shallow-earth burial grounds on the plant site 2O’ wide and 2O’ deep, well above the mean water table depth of 45’. Some of the wastes are packaged in concrete materials. The solid waste area is monitored by a system of wells and boreholes. On the basis of volume, military wastes are much larger than commercial wastes because the military wastes are in aqueous form and the latter is in the form of spent fuel. Other forms of radioactive wastes come from military-related operations like plutonium production, nuclear detonations, naval reactors, submarine production,missiles and other defence weapons.
Radiation Pollution from Nuclear Warfare:
Albert Einstein once said that the unleashed power of the atom has changed everything except our way of thinking. There are many concerned people who fear that one nuclear war will put us back to the stone age and you have no second chance to correct the mistake. They go all the way out to exhibit and inform people about the effects and dangers of nuclear war, and to arouse the public to assess the value of a growing nuclear arsenal as the basis of our security. We are the most powerful nation in the world, yet we can be destroyed with less than 30 minutes warning; so can the Russians. Either we have to learn to live with the Russians or we will both die at about the same time.
When the atom bombs were dropped at Hiroshima and Nagasaki on August 6, & 9, 1945, the complete destruction of the two cities was caused by light and heat which ignited everything combustible, followed by shattering shock wave. Then numerous fires raged out of control raising air temperature to about 2000 degrees fahrenheit. The thermal effects of nuclear explosions are very drastic and very destructive. A nuclear explosion releases enormous energy within a millionth of a second. The temperature rises to 15-20,000 times that of the temperature of the sun’s surface. The fire ball that touches the ground evaporates everything including concrete, steel and rock. There are many burned victims from those bomb blasts who are living today after having plastic surgery.
People may receive doses to the whole body from penetrating radiation, or to specific internal organs from drinking water or eating food which is contaminated from fallout or by breathing contaminated air. During the Bikini bomb test on March 3lst, 1954, a girl had beta-particle burns, twenty nine days after the fallout, even though she was 100 miles away from the bomb blast. When genetic cells from the reproductive system are damaged, mutation or cancer may result and affect many generations to come.
Evaluation:
Vocabulary:
Pick out the important vocabulary words, list them down, and write a sentence that brings out the full meaning of the word.
Questions
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1). What are the various radioactive effects on biological organisms?
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2). What are the units by which radiation is measured?
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3) What do you think is the most serious form of radiation?
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4) List the different types of radiation pollution from commercial power plants.
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5) Write a report of “the three mile island” and “the Chernobyl incident”. You can ask the librarian to help you find the proper references. Suggest your own solutions to prevent such accidents in the future.
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6) What are the dangers of nuclear war?
