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Nuclear Engineering Department , Alexandria University
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Arab Republic of EGYPT
Alexandria university
Faculty of Engineering
Nuclear Engineering Department
Trends in nuclear power production
Contents
1) Introduction.
2) History of nuclear energy production.
3) Nuclear power growth in the United States.
4) Worldwide growth of nuclear power.
5) Problems faced by nuclear energy.
6) Nuclear energy gets a second look
7) Nuclear energy statistics.
The production of nuclear power till now depends on the controlled nuclear Fission of heavy elements. This represents the most important technical application of nuclear reactions at the present time. This is so because the world's reserves of energy in the nuclear fuels uranium and thorium greatly exceed the energy reserves in all the coal, oil, and gas in the world, because the energy of nuclear fuels is in a form far more intense and concentrated than in conventional fuels, and because in many parts of the world power can be produced as economically from nuclear fission as from the combustion of conventional fuels. The energy a nuclear fuel such as uranium holds is so large. A pound of enriched fuel contains nearly three million times the energy in a pound of coal. However its radioactive power demands elaborate precautions during plant construction and operation and in the safe disposal of waste, which is still an unsolved problem and a subject of anxious study.
2. EARLY HISTORY OF NUCLEAR POWER
( The Hopes and the Reality)
General perceptions of nuclear energy, among both the public and policy makers, have undergone dramatic shifts in the past 50 years. As nuclear energy emerged in 1945 from scientific obscurity and military secrecy, it began to be talked of in speculative terms as an eventual power source. Within a decade an enthusiastic vision developed of a future in which nuclear power would provide a virtually unlimited solution for the world's energy needs. It was not difficult to picture nuclear power as the ideal energy source. With the use of breeder reactors, it would be ample in supply. As experience was gained in reactor construction, it would become economical. And because a nuclear reactor would emit virtually no pollutants, it would be clean, especially in contrast to coal.
There was also a negative side, as some doubters pointed out from the first. Very large amounts of radioactivity would be produced. In principle, practically none need escape, but the possibility of mishaps could not be totally excluded. Further, benign nuclear energy had a malign sibling in nuclear weapons. While it was realized that a reactor itself could not explode like a bomb, there were fears that in some way controlled nuclear energy might go out of control.
The optimists prevailed for two decades, into the early 1970s, and many nuclear reactors were designed, built, and put into operation in the United States and Europe. Part of the motivation for this development was the desire of countries to reduce their heavy dependence on oil, which, they realized, would eventually be in short supply. The first oil crisis came in 1973, even sooner than had been anticipated. Just as the nuclear buildup was gaining momentum, an oil embargo was imposed by the oil-rich Persian Gulf countries as a sequel to the October 1973 war between Egypt and Israel.
An immediate impulse was to rely even more on nuclear power as a substitute for oil. This was especially true in the United States, where nuclear energy had already appeared to many, including the federal government, as an important key to "energy self-sufficiency."' But the embargo had unanticipated effects. It focused new attention on the possibility of reducing all energy consumption, and rising prices slowed the pace of economic growth. These factors sharply reduced the demand for electricity and therefore the pressure to add new nuclear power plants. At the same time, the costs of nuclear power and fears about nuclear power both began to grow. The Three Mile Island accident in 1979 and the Chernobyl accident in 1986 hit a world becoming more attuned to believing the worst about nuclear power.
Nuclear energy development was stopped or brought to a crawl in all but a few countries during the 1980s and early 1990s. Contributing factors to this decline included a gradual reduction in oil and gas prices, rising nuclear costs, the sluggishness of the growth in energy demand, general fears of nuclear power, and in some countries determined campaigns against it. By 1994 it was easy to think that the age of nuclear power was coming to an end. The apparent rise and fall of nuclear power came quickly: Virtually unheard of in 1944, it was the panacea of 1974 and the pariah of 1994.
But this is an incomplete picture. There was always less unanimity than this description suggests. Not only were there scientists who were aware of nuclear power's potential in 1944, but, more significantly, there were skeptics in 1974, and there remain enthusiasts in 1994. The final verdict has not been given. Nuclear power may seem to be dormant in Germany and dead in Italy, but across the borders in France, it is thriving. The actual picture varies from country to country, with considerable complexity and uncertainty in most industrialized countries.
In the succeeding chapters we will pay only passing attention to the political and psychological factors that have influenced the changing assessments of nuclear power. Instead, the emphasis will be on describing the functioning of nuclear reactors, the extent to which they are used, and the problems surrounding their use. Issues of history and public attitudes will not be totally ignored, but the physical functioning of nuclear power, rather than its social functioning, will be the primary focus.
3) NUCLEAR POWER GROWTH IN THE UNITED STATES
2.1 History of Reactor Orders and Construction
The First Reactors
The Shippingport reactor, the first to provide commercial electricity in the United States, was a unique case. Although used for commercial electricity supply, it was largely financed by the federal government and built under navy leadership. Following the order of the Shippingport reactor in 1953, there was a fitful pattern of occasional orders over the next ten years. The only sizable reactors (>100 MWe) ordered before 1962 were the 265-MWe Indian Point 1 (New York), the 207-MWe Dresden 1 (Illinois), and the 175-MWe Yankee Rowe (Massachusetts) reactors, which were ordered in 1955 and 1956 [15].14 The first of these to go into operation was Dresden 1, in 1960.
The early period of reactor development was characterized by extensive exploration, with a wide variety of reactors being developed for military and research applications and for electricity generation. For the latter, a total of 14 reactors were ordered in the period from 1953 through I960. With the three exceptions cited above, all had capacities under 100 MWe. They included nine light water reactors (LWRs), not identical by any means, plus five other reactors with a wide variety of coolants and moderators.
Growth Until the Mid-1970s
The exploratory period ended quickly. There was a brief lull in reactor orders after 1960, with only five more orders until 1965, and then a period of rapid expansion. The dominance of LWRs in reactor orders was complete after 1960, the only exception being the gas-cooled Fort St. Vrain reactor, ordered in 1965.
None of the reactors ordered before 1962 had a capacity of as much as 300 MWe. After that, there was a substantial escalation in reactor size, in an effort to gain from expected economies of scale. Some critics believe that the growth in size was too fast to permit adequate learning from experience. The mean size of reactors ordered in 1965 was about 660 MWe, and by 1970 the mean size exceeded 1000 MWe, with some above 1200 MWe. The largest reactors completed and licensed to date in the U.S. have a (net) capacity of 1250 MWe.
Developments Since the Mid-1970s
The history of the deployment of nuclear reactors from 1953 through 1993 is shown in Fig. I.I, which gives the cumulative capacities of reactors ordered and of reactors licensed to operate.
There was a period of rapid growth in the number of orders from 1965 to 1975. At first, reactors were completed within about six years, and by the early 1970s nuclear power had begun to assume significant proportions. At the end of 1974 there were about 50 reactors in operation, with a total capacity of well over 30 GWe, providing 6% of U.S. electricity.
After 1974 the rate of putting reactors into operation slowed, due to a drop in the growth in electricity demand. There was a sharp further slowdown following the Three Mile Island accident in 1979 and then a resumption in the early 1980s with the completion of reactors ordered earlier. At the end of 1994 there were 109 operating reactors in the U.S., with a capacity of about 99 GWe.18 All are light water reactors. Net generation in 1994 was 640 billion kilowatt-hours, or 73 gigawatt-years (GWyr). The fraction of electricity provided by nuclear power has risen to over 20% in recent years, amounting to 22% in 1994. Through 1990 the driving force in the increased nuclear generation was the addition of new reactors. Since 1990 there has been an increase due to improved operation of existing reactors, with little net change in capacity.
In addition, there were six other reactors in the pipeline as of the end of 1994. Many of these face uncertain fates and may never be completed, although in all cases construction was at least 45% completed and in most cases more than 60% completed. Thus, the number of additional reactors brought on line in the 1990s will be very small, and nuclear power in the United States has reached a plateau. There may be some further improvement in operating performance, but the few additional reactors and the possible improvements could well be balanced or outweighed by additional shutdowns of reactors.
2.2 Reactor Orders and Cancellations
A striking feature of the data shown in Fig. 1.1 is the large number of cancellations of reactors that had been ordered. These cancellations are reflected in the drop in the remaining "commitments." Commitments are here denned as the sum of the number of operating reactors and the number of reactors that are at least nominally still under construction or awaiting an operating license. They equal the total number of original reactor orders, less the number of cancelled orders and the number of reactors that have been shut down. Overall, the rapid drop in commitments after 1974 reflects the cancellations, a dearth of new orders, and a few shutdowns. This history is summarized in Table 1.1, which gives the cumulative record of nuclear reactor orders and construction, from the 1950s to the end of 1994.
As seen in Table 1.1, more than half of the reactors that were ordered since 1953 have been cancelled. In some cases, this occurred after construction had started. The large number of cancellations was due in part to unrealistic projections for the growth in electricity use. After 1974, with some slowing of economic growth and a new emphasis on conservation, electricity sales grew at a much slower rate than in previous decades. Utilities that had placed earlier orders found themselves with a surplus of planned capacity. This plus the substantial opposition to nuclear power that arose in the 1970s and intensified after the Three Mile Island accident in 1979 led to the many cancellations.
Quantitative detail on the history since 1953 is shown in Fig. 1.2, which indicates the numbers of reactors ordered in each year and the number of these orders that were not cancelled, i.e., that were built or remain under construction. Most reactors ordered by 1970 were eventually built. After 1970 there was a large surge in orders, but most of these were later cancelled, including all orders placed in 1974 and later. New orders fell abruptly in 1974 and 1975, and no orders have been placed since 1978. Overall, almost all reactors now in operation were ordered in the period from 1965 through 1973. This is a strikingly compressed interval, and one that did not allow much opportunity for the manufacturers and utilities to learn from experience.
2.3 Failures of Prediction
The changing fortunes of nuclear power in the United States can be seen by comparing early projections for its growth with the actual subsequent developments. In 1972 the Forecasting Branch of the AEC Office of Planning and Analysis made a projection of future growth in nuclear capacity, based on past trends in energy use and increases in electricity capacity.
Its forecasts for the "most likely" case are shown in Fig. 4, together with the actual history. The projected capacities for 1990 and 2000 were 508 GWe and 1200 GWe, respectively. The actual capacity for 1990 was 100 GWe, and it cannot be much greater for the year 2000.
This was a spectacular failure of prediction, but one, which was in tune with the conventional wisdom of the time. It is natural to speculate as to the implications for today. Alternatively, we can congratulate ourselves on our present ability to avoid comparable errors, or we can wonder what new predictive errors are now being committed.
4) WORLDWIDE GROWTH OF NUCLEAR POWER
The discussion above has emphasized the U.S. nuclear program. But the United States was not alone in having an early interest in nuclear energy. Other countries had similar interests, although their development lagged because they lacked the head start provided by the World War II atomic bomb program and they had smaller technological and industrial bases.
For countries that wanted nuclear weapons, the priority was the same as that of the United States. The bomb came first and peaceful nuclear energy later. Thus, the construction and testing of nuclear weapons was achieved by the USSR in 1949, Britain in 1952, France in 1960, and China in 1964. Commercial nuclear electricity followed: the USSR started with several 100-MWe reactors in 1958; Britain with two 50-MWe reactors at Calder Hall in1956 (preceding the U.S. reactor at Shippingport); France with a 70-MWe prototype reactor at Chinon in 1964; and China with a 300-MWe reactor that was essentially finished in 1991 but was not listed as being in commercial operation until 1994.
Additional countries had no intention of building nuclear weapons and went directly to nuclear reactors. These included other countries of Western Europe beyond France and Britain, as well as Japan. As in the United States, the reactors for electricity generation put into operation in the late 1950s were relatively small in size and number. Large-scale worldwide exploitation of nuclear power did not begin until the 1960s and remained on a relatively modest scale until the 1970s. The major expansion came after 1973, with world nuclear power generation rising by more than a factor of ten between 1973 and 1992.
Changes in nuclear generation from 1973 to 1994 are shown in Fig. 5 for several countries. France, Japan, and Germany began major programs after the United States but have had larger fractional growth rates. In France and Japan growth has been particularly strong and, unlike the case for Germany, is continuing. South Korea, the latest major entry, has had rapid growth in the past decade, but its overall program is still relatively small. The United Kingdom, one of the original leaders in nuclear power, has lagged substantially.
By 1993 nuclear power provided over 6% of the world's commercial primary energy and about 18% of the world's electric power. Summary data on the role of nuclear power and its growth from 1973 to 1993 are shown in Table 3 for the world, the countries in the Organization for Economic Cooperation and Development (OECD), the United States, and the most successful nuclear country, France.
Some of these data might seem to suggest a vigorous and thriving enterprise. This is not the case in most countries. World nuclear power generation rose from 191 TWh in 1973 to 2080 TWh in 1993, corresponding to an average increase of 13% per year or a doubling time of under six years.26 But this rapid increase has ended. From 1988 to 1993 the average annual increase was only about 3%, and the increases can be expected to be even smaller for the remainder of the 1990s, due to the small number of new reactors in the construction pipeline.
Few new reactors are going into operation, and the shutdown of old units has meant a very slow increase in total nuclear capacity, averaging well under 2% per year from 1988 to 1993. Nuclear power's share of total world electricity generation stayed roughly constant from 1988 to 1993, rising only from 17% to 18% in this period, following two decades of rapid increases.
Data for all countries with nuclear power are presented in Table 4, which gives for each country its nuclear generation and nuclear power's fraction of its total electricity generation.
As of the end of 1994 there were 424 operating reactors in the world, distributed among 30 countries, with a combined net generating capacity of 338 GWe. Nuclear power accounted for roughly 18% of world electricity generation in 1994 and for much larger fractions in many countries, headed by France, which for several years has obtained more than 70% of its electricity from nuclear power.
The number of new reactors coming on line in recent years has been partly balanced by cancellations. Thus the comparable figures for the end of 1989 were 416 reactors with a capacity of 311 GWe. Among the larger changes in the following five years were the shutdown after German unification of five Soviet-manufactured LWRs in the former East Germany and the startup of eleven new reactors in Japan.
5) PROBLEMS FACING NUCLEAR ENERGY AND HOW TO SOLVE THEM
The decline in the growth of nuclear power discussed in the preceding sections can be attributed both to a less favorable economic environment and to concerns about the safety of nuclear power. The nuclear decline is not universal, with France, Japan, and South Korea standing as conspicuous exceptions. Nevertheless, for the world as a whole, there has been a dramatic difference between the expectations of 1970 and the reality of today.
Some of the reasons have been economic. A slowing in the overall growth in energy consumption has lessened the strain on fossil fuel supplies. That strain was further relieved by additional oil and gas production in many parts of the world and the partial replacement of fossil fuels by nuclear power. In this changed balance between supply and demand, fossil fuel prices have dropped since the early 1980s, even when expressed in current dollars.29 In the meantime, nuclear power costs have risen. Thus, in many countries, including the United States, nuclear power has lost its cost advantage over coal and even natural gas.
But economic factors are only part of the story. There has also been widespread concern over the possibility of reactor accidents, the disposal of the radioactive wastes from nuclear power, and the possibility that nuclear fuel or nuclear facilities might be diverted from reactors and used to produce nuclear bombs. Part of the increase in costs stems from measures taken in response to these concerns.
What Makes Nuclear Power Plants Safe?
Nuclear power plants use "safety in depth." This means the plant has multiple backup safety systems. The plant also has several barriers to prevent the escape of radioactive material. These barriers are: the fuel pellets, the fuel rods that hold the pellets, me large steel pressure vessel that holds the fuel rods, and a massive reinforced concrete structure that encloses everything.
Nuclear Power Plants Are Good for the Environment
Nuclear power plants are good for the environment and good to the environment. Nuclear plants don't pollute the air. They don't produce any carbon dioxide—the major greenhouse gas—or any sulfur dioxide or nitrogen oxides. The small amount of waste that a nuclear plant produces is carefully contained and safely stored. Radiation levels are checked 24 hours a day, seven days a week. Most nuclear plants have a nature park or wildlife sanctuary.
6) Nuclear Power Gets a Second Look
(Political, economic, and environmental considerations may be recasting this controversial form of energy in a favorable light)
The last nuclear power plant built in the United States was ordered in 1978, the year before the Three Mile Island accident stopped the growth of the U.S. industry in its tracks. But, just in the past year. The U.S. Nuclear Regulatory Commission extended for 20 more years six U.S. power plants operating licenses, which were about to expire after 40 years.
The Bush administration's energy plan, released in May, stated that nuclear energy is an essential part of the national energy mix, and directed the Department of Energy to support the expansion of nuclear power generation in the United States as "a major component of national energy policy."
Public opposition to nuclear power, which had been strong since the accident at Three Mile Island, demonstrably weakened.
Nuclear engineering enrollments at colleges, long in decline, started to climb.
What factors have triggered this rosier view of nuclear power? For one, earlier this year, when California instituted rolling blackouts, large numbers of people were, for the first time, hit again and again by shortfalls in electrical generating capacity. And they didn't like it. When possible solutions were laid out, nuclear power was on the list. Then, while gas and oil prices did drop from their spring highs, the September tragedy highlighted U.S. dependence on Middle East oil. One way of decreasing that dependence, again, is nuclear power.
For another, most doubts about the reality of global warming have been laid to rest. Weather patterns have changed, glaciers have shrunk. Earlier this year, a United Nations team of scientists warned of massive flooding, drought, and other cataclysmic events due in mere decades if global warming isn't halted. Some power generation technologies contribute to global warming, and alternatives them are being laid out for serious discussion. Against nuclear power is on the list.
Clearly, it is time to take a new look at nuclear power.
Public opinion
Public attitudes have a huge impact on the fate of this technology. Editor Steve Miller set out to see if the public supports the belief that they are changing. He found that today supporters of nuclear power in the United States, while no majority, often exceed those who oppose it. The shift in attitude is not universal—Germany this year voted to shut down its nuclear plants over the next 20 years, and other countries like Sweden and Switzerland, are making similar commitments. But it is a big change since the 198os.
Waste disposal
Waste disposal continues to he the major obstacle to the growth of nuclear power.
Editor Glenn Zorpette reports that, while not a single country has managed to find more than a temporary resting place for its nuclear waste, utilities finally have a technique that will let them seal the waste safely for several decades.
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Statistics of nuclear energy: -
