Nuclear power is not enough

Presently, nuclear power is developed by fission reactions in nuclear reactors. Mainly, it is used for generating of electricity. The reactors in operation are all burner reactors. They use only the Uranium U-235. This isotope is present to the extent of less than 1 per cent in naturally occurring Uranium.

Nuclear fission is a special type of nuclear reaction in which an excited compound nucleus breaks up generally into two fragments of comparable mass numbers and atomic numbers. Fission usually occurs amongst the isotopes of heaviest elements known e.g., Uranium, Theorium etc.

Nuclear fission was discovered by the two German chemists Otto Hahn and F. Strassmann in 1939.It happened to be one of the most important discoveries in nuclear physics, since it paved the way for the utilization of the internal energy of the nucleus for practical purposes. The nuclear fission discovered by Hahn and Strassmann can be symbolically written as

²³⁵U₉₂ + ¹n₀ → ²³⁶U₉₂^* → ¹⁴¹Ba₅₆ + ⁹² Kr₃₆ + 3 ¹n₀

Nuclear fission is a highly exoergic reaction. Various experiments have established that the total kinetic energy of the two fission fragments is about 167 Mev, which shows the enormity of the energy release in the fission process, compared to the energy release in an ordinary nuclear reactions. Beside, the fission fragments, some energy is also carried by the γ-rays and a few prompt neutrons emitted along with the fragments during fission.

The energy release per gram of ²³⁵U in reaction like above is 2.29×10⁴kWh. A thermal power generator having a capacity of 1 Mev (heat) would have to be run for 229 hours to generate this amount of energy. The mass of coal which must be burnt to produce an equivalent amount of energy is 2.56×10³ Kg. The above estimates clearly show the advantage of using Uranium for power generation.

To utilize the enormous amount of energy, the first nuclear reactor to be built for central station power generation was completed in 1954 in the U.S.S.R. About 5 MW electrical power was generated by this reactor. In the USA the first central-station power plant was built at Shippingport, Pennsylvania in 1957.

Naturally occurring Uranium contains three isotopes, U²³⁴, U²³⁵ and U²³⁸. The relative percentages of these isotopes are as follows:

U²³⁴ 0.006 per cent,

U²³⁵ 0.711 per cent,

U²³⁸ 99.283 per cent .

Of these isotopes, only U²³⁵ undergoes spontaneous fission when subjected to bombardment by slow neutrons. It is in fact the only naturally occurring fissile materials. The break-up of U²³⁵ when subjected to neutron bombardment yields fission products, neutrons and the release of a large amount of energy as heat (8.2×10⁷ KJ per gram of U²³⁵). The neutrons are slowed down by a moderator, and used to bombard the U²³⁵ nucleus again, thereby setting up a controlled chain reaction. A nuclear reactor working on the above reaction and utilizing only U²³⁵ is called a burner reactor. All reactors working in present day nuclear power plants are essentially burner reactors and thus waste the abundant U²³⁸ isotopes present in naturally occurring Uranium.

Although U²³⁸ is not a fissile material, it is a fertile material, i.e. it can be converted by neutron bombardment into a fissile material, Plutonium 239. Similarly, naturally occurring Thorium 232 is also a fertile material. It can be converted into U²³³ which is fissile material. The breeder reactor is the reactor in which these fertile materials are used to achieve fissile materials and the fissile materials break-up into fission products, neutrons and energy. Power breeders are considered the best possible solution for the production of economical nuclear power.

Reactors working on various breeder cycles have been built. However, the major effort has been on liquid-metal cooled, fast breeder reactors working on the U²³⁸ to Pu²³⁹ cycle. In the seventies, it appeared that breeder reactors would be in commercial operation by the turn of the century. However, fears of nuclear accidents, difficulties associated with radioactive waste disposal and the possibility of Plutonium being misused for weapons have caused the breeder development program to be closed or to be slowed down in some countries.

However, the world’s resources of Uranium are estimated to lie in the range of 3.5Mt to 6.6Mt. Of this, 2.315Mt is classified as reasonably assured reserves. A nuclear power plant uses 0.15 to 0.2t of fuel per year (in the form of Uranium Oxide) for every megawatt of capacity. Thus the reserves would be adequate for running the present installed capacity of 350 000 MW for a period of only about 35 years. It is evident that a difficult situation will arise by 2020AD or 2030AD if the present technology continues to be used.

It is thus fairly evident that a need exists for developing alternative energy sources. The immediate need would be to alleviate the problems caused by the depletion oil and natural gas, while the long term need would be to develop means to replace presently used nuclear fission technology and then coal.

Man and Energy

Man has needed and used energy at an increasing rate for sustenance and well-being ever since he came on the earth a few million years ago. Primitive man required energy mainly in the form of food. He got this by eating plants or animals which he hunted. Subsequently he discovered fire and learnt how to use it. He used fire for cooling as well as for keeping himself warm. Thus his energy needs increased day by day and he started to make use of wood and other biomass to supply the energy.

After a while, man started to cultivate land for agriculture. For domesticating and training animals to work for him he needs more energy. With further demand for energy, man began to use the wind for sailing ships and for driving windmills, and the force of falling water to turn water wheels. Till this time it would not be wrong to say that the sun was supplying all the energy needs of man either directly or indirectly and that man was using only renewable sources of energy.

With the discovery of the steam engine (A.D 1700), the Industrial Revolution began and brought about a great many changes. For the first time, man started to use a new source of energy – coal, in large quantities. A few years later, the other fossil fuels, oil and natural gas began to be used extensively. The fossil fuel era of using nonrenewable sources had begun.

Man started to produce electricity using either fossil fuels or water power and he developed power generating stations. The electricity brought a great change in man’s movement. For the first time, man got the power of machine.

A new source of energy- nuclear energy- came on the scene after the Second World War.

Already, nuclear energy is providing a small but significant amount of the energy requirements of many countries.

In the past few years, it is obvious that fossil fuel resources are fast depleting .This is particularly true for oil and natural gas. Thus the fossil fuel era is gradually coming to an end. Based on the World wide survey(shown in fig.), it will now be possible to make some observations and draw some conclusions for the world as a whole.

a) The production of oil appears at maximum around 1980 and is now slowly declining. On the other hand, the production of natural gas is still rising. Present data shows that most of the reserves of oil and natural gas are likely to be consumed in another 50 years.

b) As oil and natural gas become scarcer, a great emphasis will fall on coal. The production of coal likely will touch a maximum somewhere between the years 2030 and 2060 and it could be consumed by 2250 AD.

Thus the need for alternative energy sources will be established. Now it is obvious that though man’s large scale use of commercial energy (coal, oil, natural gas, hydroelectric power and nuclear power) has brought a better quality of life, it has also brought many problems. Perhaps the most serious of these is the harmful effect on the environment. It causes serious air pollution problems in many areas because of the localized release of large amounts of harmful gases into the atmosphere. It causes the phenomenon of global warming which now a matter of great concern. Keeping the environment in mind, now we are badly in need of alternative energy sources. Later part of this sires, I’ll discus about some of them.

Thank you.

Not Catastrophism: Erosion of Earth

In the eighteenth century scientists believed that Earth’s surface had remained unchanged until cataclysmic events (like the flood of Noah)-called catastrophism. Catastrophism claimed that all of the changes in the earth’s surface were the result of sudden, violent (catastrophic) changes. In that time scientists tried to understand the planet’s surface structures by using Catastrophism. They studied the earth, its history, its landforms, and its age based on Catastrophism. And they led to wildly inaccurate guesses and misinformation.

But in the 1780s, 57-year-old, James Hutton (amateur geologist) decided to try to calculate the age of the earth more accurately by studying the earth’s rocks. And soon he realized that something possibly was wrong with Catastrophism and no catastrophic event could explain the rolling hills and meandering river valleys.

The earth, Hutton realized, was shaped slowly, not over night. Rain and wind are the main forces which change our Earth’s surface bit by bit, year by year. He discovered that the earth’s surface continually and slowly changes, evolves. He discovered the processes of erosion of Earth that gradually built up and wore down the earth’s surface. And water, wind, ice and wave (coastal erosion) are the main agents of erosion that change the shape of the earth’s surface.

But what built up the earth? He finally concluded that the heat of Earth’s core built up hills and mountains by pushing out ward. Mountain ranges were forced up by the heat of the earth. Wind and rain slowly wore them back down. With no real beginning and no end, these two great forces struggled in dynamic balance over eons, the real time scale for geologic study.

With that great discovery, James Hutton forever changed the way geologists would look at the earth and its processes. This discovery provided the key to understanding our planet’s history and launched the modern study of earth sciences.
However you may enjoy some clips on youtube about power of wind and atomosphere-here is one of them in Arizona
http://www.youtube.com/watch?v=aBnGqQN_9hQ

Third law of Thermodynamics: is it broken?

There are always some invisible barriers in the physical science - the edge of the detectable universe-the cosmological horizon is one, and the relativistic speed limit,Beyond which no object can accelerate, is another .A third such barrier is absolute zero Temperature, the state beyond which matter cannot be cooled, in which all molecular motion ceases .

Absolute zero, as a theoretical concept, was found as early as 1699, in the work of the French physicist Guillaume Amontons, conducted experiments in temperature and it’s measurement, but still it is a mystery why it is unattainable. The numerical value of absolute zero is -273.15 degrees Celsius or -459.67 degrees Fahrenheit.

The first significant step in the direction of achieving absolute zero was taken in the 1880s when a French mining engineer named Louis-Paul Cailetet liquefied Oxygen,At about-200 degrees Fahrenheit .Today, when temperature of less than a degree above Absolute zero are achievable, this trend continues at the University of Florida, is Gainesville, where a new cryogenics laboratory has been opened recently.

The first law of thermodynamics (also known as law of conservation of energy) holds that energy can neither created nor destroyed. It establishes an exact relation between heat and work. But it does not tell us the direction of energy transformation.

The second law, which governs the direction of the flow of heat, dictates that during every transformation of energy, a certain amount is dissipated and so, is unavailable for doing work. It introduces a new thermodynamic variable named Entropy which is the measurement of disorder. With disorder, entropy increases.

By an orderly sate of molecules in a substance we mean that at any instant we can be sure in specifying their arrangement within the substance.

The third one was proposed, in 1906, by Walther Nernst, of the University of Berlin (for which he won the 1920 Nobel Prize in chemistry).

Physicists previously had assumed that, when cooled, molecules and atoms gradually slow down until, at absolute zero, they come to rest. But Quantum Mechanics does not allow that. The lowest energy available to an atom, called its ground state energy, is not zero. The associated with this state cannot be shared with other objects ( it cannot “flow”) or be interpreted as heat, so it does not count as disorderliness. Reasoning in this manner, Nernst reached at a new understanding of absolute zero: rather than the absence of motion, it indicates the absence of disorder, that means, a state of perfect order.

Surveying the specific heat –six year latter Nernst discovered a remarkable fact: During the approach toward absolute zero, or perfect order, each step is more difficult than the preceding one. Temperature decreases less with each successive removal of heat. Nernst proposed a stronger form of the third law: Absolute zero is unattainable.

In principle, according to the statistical nature of order, there is a small but finite probability that an object will reach a temperature of a billionth of a Kelvin, or even zero. This is the base of Gainesville physicists.

Oceans Control Global Weather

By pumping massive amounts of heat through the oceans, vast ocean currents control weather and climate on land.

American statesman, inventor, and scientist Benjamin Franklin conducted the first scientific investigation of the Gulf Stream at 1770 and discovered its importance to Earth’s weather

and climate. His work launched scientific study of ocean currents, ocean temperature, the

interaction of ocean current with winds, and the effect of ocean currents on climate. Franklin’s discoveries mark the beginnings of modern oceanographic science.

The Atlantic Ocean’s Gulf Stream is the most important of our world’s ocean currents.

It is a major heat engine, carrying massive amounts of warm water north to warm Europe. It

has directed the patterns of ocean exploration and commerce and may be a major determinant of the onset of ice ages. Finally, it is the key to understanding global circulation patterns and the interconnectedness of the world’s oceans, weather, and climates.

The Gulf Stream is bigger than the combined flow of the Mississippi, the Nile, the Congo, the Amazon, the Volga, the Yangtze,and virtually every other major river in the world.

Cancer and Power lines

Epidemiologists in Denver , Los Angeles and Sweden are asking us to believe that magnetic fields of 2 milligauss from power distribution lines are a serious cause of childhood Leukemia . And they believe that low frequency electromagnetic fields ( like ovens and TV sets) of modern life threaten our health .

However, laboratory studies on animals and cell cultures have shown that weak magnetic fields can have effects on several biological processes. For example, they may alter hormone and enzyme levels and the rate of movement of some chemicals through living tissue. In the long term, they may have an effect on the incidence of cancer or other adverse health effects.

But the studies have been criticized . The studies were using data gathered from second hand

sources . They all suffer inadequate statistical samples ; in some cases , it is as little as only one case of cancer per year . The studies are mutually inconsistent and self- contradictory .

Well , "Do the all-pervasive low-frequency electromagnetic fields of modern life threaten our health ? Most probably not , judging from comparisons with the natural fields present in the

environment and in our bodies ." said William R. Bennett Jr , is a professor of Physics at

Yale University .

Well , Let's consider some natural sources of exposure .

The Earth's magnetic field is generated predominantly by circulating currents of uncertain origin well below the crust . The fields varies over the Earth's surface from about 300 mG at the equator to 700 mG at the poles .A representative value over the continental United States is

about 450 mG , about 200 times that from typical distribution lines . The magnetic field may vary about 0.1-0.3 mG due to photoionization of molecules in the upper atmosphere . For unusual solar activity sudden fluctuations often exceed 100 mG .

Again Earth's static electric field is directed downward normal to the earth's surface and is about

120 V/m near ground level , about three times the field from a 12-KV distribution line .

So, If you live in a house near one of these high-voltage power lines, you shoud not move.

But based on what we know now, we can never say there is no risk, but we can say that the risk appears to be extremely small.

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