Nuclear Energy

Radioactive wastes, must for the protection of mankind be stored or disposed insuch a manner that isolation from the biosphere is assured until they havedecayed to innocuous levels. If this is not done, the world could face severephysical problems to living species living on this planet. Some atoms candisintegrate spontaneously. As they do, they emit ionizing radiation. Atomshaving this property are called radioactive. By far the greatest number of usesfor radioactivity in Canada relate not to the fission, but to the decay ofradioactive materials – radioisotopes.

These are unstable atoms that emit energyfor a period of time that varies with the isotope. During this active period,while the atoms are ‘decaying’ to a stable state their energies can be usedaccording to the kind of energy they emit. Since the mid 1900’s radioactivewastes have been stored in different manners, but since several years new waysof disposing and storing these wastes have been developed so they may no longerbe harmful.

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A very advantageous way of storing radioactive wastes is by aprocess called ‘vitrification’. Vitrification is a semi-continuous process thatenables the following operations to be carried out with the same equipment:evaporation of the waste solution mixed with the borosilicate: any of severalsalts derived from both boric acid and silicic acid and found in certainminerals such as tourmaline. additives necesary for the production ofborosilicate glass, calcination and elaboration of the glass. These operationsare carried out in a metallic pot that is heated in an induction furnace.

Thevitrification of one load of wastes comprises of the following stages. The firststep is ‘Feeding’. In this step the vitrification receives a constant flow ofmixture of wastes and of additives until it is 80% full of calcine. The feedingrate and heating power are adjusted so that an aqueous phase of several litresis permanently maintained at the surface of the pot. The second step is the ‘Calcinationand glass evaporation’. In this step when the pot is practically full of calcine,the temperature is progressively increased up to 1100 to 1500 C and then ismaintained for several hours so to allow the glass to elaborate. The third stepis ‘Glass casting’. The glass is cast in a special container.

The heating of theoutput of the vitrification pot causes the glass plug to melt, thus allowing theglass to flow into containers which are then transferred into the storage.Although part of the waste is transformed into a solid product there is stilltreatment of gaseous and liquid wastes. The gases that escape from the potduring feeding and calcination are collected and sent to ruthenium filters,condensers and scrubbing columns.

The ruthenium filters consist of a bed ofcondensacate: product of condensation. glass pellets coated with ferrous oxideand maintained at a temperature of 500 C. In the treatment of liquid wastes, thecondensates collected contain about 15% ruthenium. This is then concentrated inan evaporator where nitric acid is destroyed by formaldehyde so as to maintainlow acidity. The concentration is then neutralized and enters the vitrificationpot.

Once the vitrification process is finished, the containers are stored in astorage pit. This pit has been designed so that the number of containers thatmay be stored is equivalent to nine years of production. Powerful ventilatorsprovide air circulation to cool down glass. The glass produced has the advantageof being stored as solid rather than liquid. The advantages of the solids arethat they have almost complete insolubility, chemical inertias, absence ofvolatile products and good radiation resistance. The ruthenium that escapes isabsorbed by a filter. The amount of ruthenium likely to be released into theenvironment is minimal. Another method that is being used today to get rid ofradioactive waste is the ‘placement and self processing radioactive wastes indeep underground cavities’.

This is the disposing of toxic wastes byincorporating them into molten silicate rock, with low permeability. By thismethod, liquid wastes are injected into a deep underground cavity with mineraltreatment and allowed to self-boil. The resulting steam is processed at groundlevel and recycled in a closed system. When waste addition is terminated, thechimney is allowed to boil dry. The heat generated by the radioactive wastesthen melts the surrounding rock, thus dissolving the wastes. When waste andwater addition stop, the cavity temperature would rise to the melting point ofthe rock. As the molten rock mass increases in size, so does the surface area.

This results in a higher rate of conductive heat loss to the surrounding rock.Concurrently the heat production rate of radioactivity diminishes because ofdecay. When the heat loss rate exceeds that of input, the molten rock will beginto cool and solidify. Finally the rock refreezes, trapping the radioactivity inan insoluble rock matrix deep underground. The heat surrounding theradioactivity would prevent the intrusion of ground water.

After all, the steamand vapour are no longer released. The outlet hole would be sealed. To go alittle deeper into this concept, the treatment of the wastes before injection isvery important. To avoid breakdown of the rock that constitutes the formation,the acidity of he wastes has to be reduced. It has been establishedexperimentally that pH values of 6.5 to 9.5 are the best for all receivingformations.

With such a pH range, breakdown of the formation rock anddissociation of the formation water are avoided. The stability of wastecontaining metal cations which become hydrolysed in acid can be guaranteed onlyby complexing agents which form ‘water-soluble complexes’ with cations in therelevant pH range. The importance of complexing in the preparation of wastesincreases because raising of the waste solution pH to neutrality, or slightalkalinity results in increased sorption by the formation rock of radioisotopespresent in the form of free cations. The incorporation of such cations causes apronounced change in their distribution between the liquid and solid phases andweakens the bonds between isotopes and formation rock. Now preparation of theformation is as equally important. To reduce the possibility of chemicalinteraction between the waste and the formation, the waste is first flushed withacid solutions. This operation removes the principal minerals likely to becomeinvolved in exchange reactions and the soluble rock particles, thereby creatinga porous zone capable of accommodating the waste.

In this case the equiredacidity of the flushing solution is established experimentally, while therequired amount of radial dispersion is determined using the formula: R = Qt 2mn R is the waste dispersion radius (metres) Q is the flow rate (m/day) t is thesolution pumping time (days) m is the effective thickness of the formation (metres)n is the effective porosity of the formation (%) In this concept, the storageand processing are minimized. There is no surface storage of wastes required.The permanent binding of radioactive wastes in rock matrix gives assurance ofits permanent elimination in the environment. This is a method of disposal safefrom the effects of earthquakes, floods or sabotages. With the development ofnew ion exchangers and the advances made in ion technology, the field ofapplication of these materials in waste treatment continues to grow.Decontamination factors achieved in ion exchange treatment of waste solutionsvary with the type and composition of the waste stream, the radionuclides in thesolution and the type of exchanger.

Waste solution to be processed by ionexchange should have a low suspended solids concentration, less than 4ppm, sincethis material will interfere with the process by coating the exchanger surface.Generally the waste solutions should contain less than 2500mg/l total solids.Most of the dissolved solids would be ionized and would compete with theradionuclides for the exchange sites. In the event where the waste can meetthese specifications, two principal techniques are used: batch operation andcolumn operation. The batch operation consists of placing a given quantity ofwaste solution and a predetermined amount of exchanger in a vessel, mixing themwell and permitting them to stay in contact until equilibrium is reached. Thesolution is then filtered. The extent of the exchange is limited by theselectivity of the resin. Therefore, unless the selectivity for the radioactiveion is very favourable, the efficiency of removal will be low.

Columnapplication is essentially a large number of batch operations in series. Columnoperations become more practical. In many waste solutions, the radioactive ionsare cations and a single column or series of columns of cation exchanger willprovide decontamination. High capacity organic resins are often used because oftheir good flow rate and rapid rate of exchange. Monobed or mixed bed columnscontain cation and anion exchangers in the same vessel.

Synthetic organicresins, of the strong acid and strong base type are usually used. Duringoperation of mixed bed columns, cation and anion exchangers are mixed to ensurethat the acis formed after contact with the H-form cation resins immediatelyneutralized by the OH-form anion resin. The monobed or mixed bed systems arenormally more economical to process waste solutions. Against background ofgrowing concern over the exposure of the population or any portion of it to anylevel of radiation, however small, the methods which have been successfully usedin the past to dispose of radioactive wastes must be reexamined.

There are twocommonly used methods, the storage of highly active liquid wastes and thedisposal of low activity liquid wastes to a natural environment: sea, river orground. In the case of the storage of highly active wastes, no absoluteguarantee can ever be given. This is because of a possible vessel deteriorationor catastrophe which would cause a release of radioactivity. The onlyalternative to dilution and dispersion is that of concentration and storage.This is implied for the low activity wastes disposed into the environment. Thealternative may be to evaporate off the bulk of the waste to obtain a smallconcentrated volume. The aim is to develop more efficient types of evaporators.

At the same time the decontamination factors obtained in evaporation must behigh to ensure that the activity of the condensate is negligible, though thereremains the problem of accidental dispersion. Much effort is current in manycountries on the establishment of the ultimate disposal methods. These aredefined to those who fix the fission product activity in a non-leakable solidstate, so that the general dispersion can never occur. The most promisingoutlines in the near future are; ‘the absorbtion of montmorillonite clay’ whichis comprised of natural clays that have a good capacity for chemical exchange ofcations and can store radioactive wastes, ‘fused salt calcination’ which willneutralize the wastes and ‘high temperature processing’.

Even though man hasmade many breakthroughs in the processing, storage and disintegration ofradioactive wastes, there is still much work ahead to render the wastesabsolutely harmless.Technology

Nuclear Energy

.. uld then conclude that the nuclear industry is mostly to blame for the nation wide increase of cancers and deaths.

Is the nuclear industry really benefitting the nation or is it just making the world into a radioactive dump which takes thousands of years to clean up? One last major problem with nuclear energy that needs to be touched on is the storage of nuclear waste. Nuclear waste includes all contaminated parts that have had contact with any source of nuclear energy and all products of a nuclear reaction that was discussed at the beginning of the paper. There are several problems that relate to the storage of nuclear energy.

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At a nuclear storage facility, there are security officers, technicians, scientists, and regular staff which make sure the facility is safe.In the paper, Uranium: Its Uses and Hazards, it states the half-life of some radioactive isotopes. Uranium-238 which has a half-life of 4.46 billion years and that uranium-235 which has a half-life of 704 million years represent most of nuclear waste stored at nuclear waist facilities. (1) This means that people will have to be monitoring these facilities for about ten billion years. Fred H. Knelman is very concerned about the time and man power required to run these storage facilities.

Knelman wrote : There must always be intelligent people around to cope with eventualities we have not thought of…Reactor safety, waste disposal, and the transport of radioactive materials are complex matters about which little can be said with absolute certainty. Is mankind prepared to exert the eternal vigilance needed to ensure proper and safe operation of its nuclear system? (39) The searching for proper storage facilities and places has always been one of the top priorities of the nuclear industry. The problem is that no one wants a nuclear waste facility in there back yard.

Literally billions of dollars has been spent just on looking for places to store nuclear waste. Nuclear energy has many short term benefits but many more short term and long term problems. If anyone of the lethal potential problems develop and get out of control than the world is in serious trouble. Can the world afford to be dancing with death? Just think if a nuclear plant exploded because of a terrorist attack how our lives would be changed forever.Are we unselfish enough live without a few comforts now so that our children can have a brighter future? A nuclear disaster is the worst thing that can happen to this planet because it threatens the whole future of the human race.

Nuclear energy is not worth the risk. The problem of nuclear energy such as terrorism, plutonium production, uranium mill tailings, and waste storage problems make nuclear energy too risky for humans to even experiment with. Nuclear energy holds our future in a tight grip so we must do something about it. Works CitNuclear Energy You are watching the control panels and gages for rector two.Sitting comely you think about how easy your job is. It is a joke! All day you sit around and watch the gages for reactor number two just to make sure they maintain their settings.

You don’t even need to look at the gages either because a computer automatically regulates them without you. Life is so good. Suddenly all the sirens go of and the gages and displays spin wildly in every direction.

The ground shakes and you can hear the sound of a deep rumble.Unknown to you, the reactor’s cooling pumps have failed to cool the reactor’s core and in 3 seconds the temperature went from 280 degrees centigrade to 4,000 degrees centigrade. The water that was in the reactor is instantly turned to steam which creates tremendous amount of pressure in the reactor core.

Above the reactor core there is a 5 foot thick lead plate and above that there is a meter thick floor composed of iron, barium, serpentine, concrete, and stone. The exploding steam fires the floor up like shrapnel. The metal plate goes through the four foot thick concrete roof like butter and reaches and altitude of sixty meters.You can hear ripping, rending, wrenching, screeching, scraping, tearing sounds of a vast machine breaking apart.

L. Ray Silver, a leading author who covered the disaster at Chernobyl, said that within the core, steam reacts with zirconium to produce that first explosive in nature’s arsenal, hydrogen. Near-molten fuel fragments shatter nearly incandescent graphite, torching chunks of it, exploding the hydrogen. The explosion breaks every pipe in the building rocking it with such power that the building is split into sections (11-13).You look down at your body and notice that it feels hot and your hands look different.

Unknown to you a tremendous amount of neutrons are hitting your cells and taking chucks out of your skin. Suddenly everything goes black. The paragraph above describes the scene of what happened at Chernobyl nuclear plant a few years ago.

From that time until the present many other smaller accidents have happened.From these accidents many people have died and millions have been indirectly affected. Nuclear energy has far to many negative problems than advantages. From the mining of uranium to disposal of nuclear waist there are problems of such magnitude that no scientist on this earth has an answer for. Nuclear energy has so many problems associated to it that it should be banned from the earth. To understand the threat of nuclear energy we must first understand what happens in a nuclear reaction.

Ann E. Weiss, who has written several books on the subject of nuclear energy, described what happens inside a nuclear power plant. In a nuclear reaction the nuclei of its atoms split, producing energy in the form of heat.

The heat makes steam which powers a turbine. Fission takes place in a nuclear reactor.The fuel used is pellets of uranium. In a modern reactor, half-inch long pellets of uranium are packed into 12 or 14 foot tubes made of an alloy of the metal zirconium. About 50,000 zircalloy fuel rods make up the reaction core.

To control a nuclear reaction control rods made of cadmium is used which absorbs neutrons. With the control rods in place in the core, a chain reaction cannot begin. When the plant operators want to start the chain reaction they activate machinery that pulls the control rods away from the core.

Once this is done a single free neutron is enough to set off the reaction. As the reaction continues, a moderator slows the neutrons down enough to ensure that they will continually split more uranium atoms. At the same time, the moderator acts as a coolant. It keep the overall temperature about 300 degrees Celsius. Since the temperature at spots inside the fuel rods may be as high as 1,100 degrees Celsius, enormous amounts of coolant are continually needed to keep the core temperature at the proper level. When the plant must be must be shut down the control rods are lowered all the way back into the core.That brings the chain reaction to a standstill.

The core cools, and steam is no longer produced (23-24). In all nuclear reactions use uranium and produce some plutonium. Since nuclear reactions produce a considerable amount of plutonium there are considerable hazards that come along with it. Nader and Abbotts, two men who have a great amount of experience in the nuclear industry, comment that: Plutonium’s major dangers include the fact that it is weapons-grade material, that it is highly toxic, and it is extremely long-lasting: it will take 24,000 years for half of it to decay.In addition to the possibility that plutonium could contaminate the environment or the population in an accident, there is also the danger that a terrorist group could steal plutonium for the purposes of fashioning an illicit nuclear weapon. (63) Plutonium-239 is a man-made reactor by-product which emits highly energetic alpha particles.

Even though alpha particles can be stopped by a piece of paper that can be very dangerous to tissue if they are taken into the body by ingestion or inhalation. Expressing extreme concern over the issue of plutonium getting into the human body Nader and Abbotts write: Experiments with dogs show that the inhalation of as little as three millionths of a gram of Pu-239 can cause lung cancer. John Gofman has reported that plutonium and other alpha-emitters, such as curium and americium [other products of a nuclear reaction], when in a form that cannot readily be dissolved by body fluids, ‘represent an inhalation hazard in a class some five orders of magnitude [100,000 times] more potent, weight for weight, than potent chemical carcinogens.’ The fact that plutonium has a very long half-life, 24,000 years, makes it one of the deadliest elements known and one of the most difficult to manage.(78) The reason why plutonium is so dangerous when it gets into the lungs is because plutonium releases radiation to a small mass of the lung at a very short distance. This effect of radiation from plutonium giving a concentrated dose to one small area is much greater than if the same amount of radiation had been uniformly distributed throughout the lung. Another problem with plutonium is its toxicity.

Plutonium is the most toxic of all elements. Fred H. Knelman, who was a senior executive on the nuclear control panel in Washington D.C., wrote, One pound of plutonium-239, distributed to the lungs of a large population, could cause between ten and fifteen million lung-cancer deaths (32).

Plutonium is rapidly becoming more and more common throughout the world because it is being produced all the time in nuclear reactions. The Nuclear Control Institute, in Washington D.C., published a paper on the Internet describing the problem of plutonium production. By the turn of the century, 1,400 metric tons of plutonium will have been produced in the spent fuel of nuclear power reactors, and some 300 tons of it will have been separated into weapons-usable form.

Less than 18 pounds (8 kilograms) is needed to build a Nagasaki-type bomb. The amounts will continue to grow rapidly. By 2010, there will be 550 tons of separated plutonium in commerce, more than twice the amount now contained in the world’s nuclear arsenals. By that time, Japan will have acquired an amount of plutonium equivalent to the present U.S.

military stockpile.(The Problem, 2) The quote above has a few hidden statements behind it. First it predicts that soon other nations will have a greater nuclear arsenal than the U.S.A. Also the quote says that plutonium is growing to be an excess product from nuclear reactions and thus other countries who are not economically stable will have a greater tendency to want to sell some plutonium to power hungry politicians for money to help the economy of their own country. The subject of plutonium directly relates to nuclear terrorism.

The terrorists’ holy grail is to build a nuclear bomb. It is becoming increasingly easy to find the knowledge on how to build a nuclear bomb. The only thing that is holding terrorists back is getting their hands on some plutonium or weapons-grade uranium. Christopher K.Mitchell, a student under professor J.

Ruvalds, wrote a research report in physics 177N class that stated that when constructing a nuclear weapon, there would be two main issues for a terrorist. The first issue would be the knowledge required about building the bomb and making it work. Essentially, this knowledge is not a great problem. For instance, anyone can purchase a copy of The Los Alamos Primer for approximately twenty-three dollars.This book details the work of scientist who participated in the Manhattan Project tests in New Mexico. Inside the book, a terrorist could find the amount of uranium needed to create a successful nuclear explosion. In addition, the book details the different types of nuclear bombs and how to construct them.

According to Carson Mark, a nuclear weapons specialist, a terrorist group would need some specialist, such as a nuclear physicist, a chemist, and an explosives engineer to build a nuclear weapon. In addition, some specialized equipment would be required.The second issue of building a nuclear weapon is the material needed to fuel the chemical reaction. Of the two issues, this one creates a much larger problem. Until recently, it was nearly impossible for a terrorist to even consider obtaining either bomb grade plutonium or uranium. In the past, these bomb grade fuels would have been nearly impossible to steal and the price to purchase such materials was far above the budget of any terrorist group. Many experts feel that it would cost at least five to ten million dollars to purchase enough plutonium to make a nuclear weapon. Others place the estimate as high as twenty or thirty million dollars (2).

The problems of obtaining money and scientists are not big. The Soviet Union has left many of its top nuclear scientists without jobs and money. Many would be happy to get out of their crime ridden country to work for a terrorist group or another country associated with terrorism like Iran or Iraq.

Money is not a problem for these two countries who hold some of the world’s biggest oil reserves. This paragraph represents only one type of terrorism that can be done with money and talent but what can other terrorist groups do who don’t have very much money? One very vulnerable terrorist target is the nuclear powerplants.Scott D. Portzline, who has a Ph.

D. is nuclear physics, writes that : Considering the fact that a nuclear plant houses more than a thousand times the radiation as released in an atomic burst, the magnitude of a single attack could reach beyond 100,000 deaths and the immediate loss of tens of billions of dollars. The land and properties destroyed (your insurance won’t cover nuclear disasters) would remain useless for decades and woed Corinne Brown, and Robert Munroe. Time Bomb, Understanding the Treat of Nuclear Power.New York: William Morrow & Company, Inc, 1981 Knelman, Fred H. Nuclear Energy The Unforgiving Technology. Edmonton: Hurtig Publishers, 1976.

Mitchell, Christopher K. Nuclear Terrorism.14 Nov. 1996 Available :

html. Nuclear Waste: The Big Picture. 10 Nov. 1996.Available:

Portzline, Scott D. Nuclear Terrorism. 10 Nov. 1996. Available: http://www. Ralph Nader, and John Abbotts.The Menace of Atomic Energy.

New York: W.W. Norton & Company Inc, 1977. Silver, L.

Ray. Fallout From Chernobyl.Toronto: Deneau Publishers & Company LTD, 1987. The Problem. 10 Nov. 1996. Available: http://www. Its Uses and Hazards.

20 Nov. 1996. Available :

html. Weiss, Ann E. The Nuclear Question.New York: Harcourt Brace Jovanovich Publishers, 1981. Science.


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