User:Johnfos/Nuclear power controversy

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This article is about the public controversy associated with the use of nuclear fission as a power source. For applications as a power source, see Nuclear power. For the underlying energy itself, see Nuclear energy.
A nuclear power station. The nuclear reactors are inside the cylindrical containment buildings to the right - left is a cooling tower venting steam (literally fog or man-made cloud).
A nuclear power station. The nuclear reactors are inside the cylindrical containment buildings to the right - left is a cooling tower venting steam (literally fog or man-made cloud).
Chernobyl reactor 4 after the disaster, showing the extensive damage to the main reactor hall (image center) and turbine building (image lower left)
Chernobyl reactor 4 after the disaster, showing the extensive damage to the main reactor hall (image center) and turbine building (image lower left)

After a period of decline following the 1979 Three Mile Island accident ('Harrisburg') and the 1986 Chernobyl disaster, there is a recently renewed interest in nuclear energy because it could partially address both dwindling oil reserves and global warming with far fewer emissions of greenhouse gases than fossil fuel.

The use of nuclear power is controversial because of the problem of storing radioactive waste for indefinite periods, the potential for severe radioactive contamination by accident or sabotage, and the possibility that its use could in some countries lead to the proliferation of nuclear weapons.

Proponents, including some national governments and atomic energy groups, claim that these risks are small and can be lessened with new technology. They note that the safety record is already good when compared to other energy forms and that it releases much less pollution than coal power.

Opponents, including some national governments and many environmental groups, claim nuclear power is an uneconomic, unsound and potentially dangerous energy source and dispute whether the costs and risks can be reduced through new technology. Cost and risk form a tandem - eliminating all risks (or insuring against them) would make nuclear power too expensive to compete with other alternative power sources once they have received the same amount of research funding that has already been put into nuclear power.

Whether nuclear fission is a sustainable or renewable energy source is another major point of debate.

Image:Lula nuclear.jpg
Brasilia, Brazil , March, 15, 2005 — Greenpeace balloon in Brasilia and Lula Nuclear. Greenpeace protesting against Brazilian Nuclear Program. Photo:J. Freitas/Abr.
Edward Teller as "the only victim of Three Mile Island" in his 1979 Wall Street Journal pro-nuclear ad, sponsored by Dresser Industries, the firm which had manufactured one of the defective valves which contributed to the accident.
Edward Teller as "the only victim of Three Mile Island" in his 1979 Wall Street Journal pro-nuclear ad, sponsored by Dresser Industries, the firm which had manufactured one of the defective valves which contributed to the accident.

Contents

[edit] Fuel cycle

[edit] Fuel resources

At the present rate of use, there are 50 years left of low-cost known uranium reserves - however, given that the cost of fuel is a minor cost factor for fission power, more expensive lower-grade sources of uranium could be used in the future [1] [2]. Other ideas include extraction from seawater and granite - although there is controversy on this issue. For arguments pro and against these ideas, see [3] and [4] (pro) and [5] (against).

Another alternative would be to use thorium as fission fuel in breeder reactors - thorium is three times more abundant in the Earth crust than uranium [6].

Current light water reactors make relatively inefficient use of nuclear fuel, leading to energy waste. More efficient reactor designs or nuclear reprocessing [7] would reduce the amount of waste material generated and allow better use of the available resources.

As opposed to current light water reactors which use Uranium-235 (0.7% of all natural uranium), fast breeder reactors use Uranium-238 (99.3% of all natural uranium). It has been estimated that there is anywhere from 10,000 to five billion years worth of Uranium-238 for use in these power plants [8]. Breeder technology has been used in several reactors [9]. Currently (December 2005), the only breeder reactor producing power is BN-600 [10] in Beloyarsk, Russia. (The electricity output of BN-600 is 600 MW - Russia has planned to build another unit, BN-800, at Beloyarsk nuclear power plant.) Also, Japan's Monju reactor is planned for restart (having been shut down since 1995), and both China and India intend to build breeder reactors.

[edit] Reprocessing

For more details on this topic, see Nuclear reprocessing

Reprocessing can recover nearly all of the remaining uranium and plutonium in spent nuclear fuel which make up 95% of spent fuel, for use in new mixed oxide fuel. Reprocessing of civilian fuel from power reactors is currently done on large scale in England, France and Russia, is planned in China and perhaps India, and is being done on an expanding scale in Japan. The stated reason reprocessing of civilian nuclear fuel is not done in the United States due to nuclear proliferation concerns, as ordered by President Carter.

[edit] Solid waste

For more details on this topic, see Nuclear waste.

Nuclear power produces spent fuel, a unique solid waste problem. Because spent nuclear fuel is radioactive, extra care and forethought are given to facilitate their safe storage (see nuclear waste). The waste from highly radioactive spent fuel needs to be handled with great care and forethought due to the long half-lives of the radioactive isotopes in the waste. Also, during reactor operation, the reaction chamber is bombarded with high-energy neutrons - this makes the decommissioning process more expensive when the reactor reaches the end of its life cycle (40 to 60 years for many current designs). However, spent nuclear fuel becomes less radioactive over time - after 40 years 99.9% of radiation disappears [11].

Spent fuel is primarily composed of unconverted uranium, as well as significant quantities of transuranic actinides (plutonium and curium, mostly). In addition, about 3% of it is made of fission products. The Actinides (uranium, plutonium, and curium) are responsible for the bulk of the long term radioactivity, whereas the fission products are responsible for the bulk of the short term radioactivity. It is possible through reprocessing to separate out the actinides and use them again for fuel, but this often requires special fast spectrum reactors, which produce a reduction in long term radioactivity within the remaining waste. In any case, the remaining waste will be substantially radioactive for at least 300 years even if the actinides are removed, and for up to thousands of years if the actinides are left in. Even in the most optimistic scenarios (complete consumption of all actinides, and using fast spectrum reactors to destroy some of the long-lived non-actinides as well), the waste must be segregated from the environment for at least several hundred years, and therefore this is properly categorized as a long term problem.

The average nuclear power station produces 20-30 tonnes of spent fuel each year.[12] As of 2003, the United States had accumulated about 49,000 metric tons of spent nuclear fuel from nuclear reactors. Unlike other countries, U.S. policy forbids recycling of used fuel and it is all treated as waste. After 10,000 years of radioactive decay, according to United States Environmental Protection Agency standards, the spent nuclear fuel will no longer pose a threat to public health and safety.

The safe storage and disposal of nuclear waste is a difficult challenge. Because of potential harm from radiation, spent nuclear fuel must be stored in shielded basins of water, or in dry storage vaults or dry cask storage until its radioactivity decreases naturally ("decays") to safe levels. This can take days or thousands of years, depending on the type of fuel. Most waste is currently stored in temporary storage sites, requiring constant maintenance, while suitable permanent disposal methods are discussed. Underground storage at Yucca Mountain in U.S. has been proposed as permanent storage. See the article on the nuclear fuel cycle for more information.

The nuclear industry produces a volume of low-level radioactive waste in the form of contaminated items like clothing, hand tools, water purifier resins, and upon decommissioning the materials of which the reactor itself is built. In the United States, the Nuclear Regulatory Commission has repeatedly attempted to allow low-level materials to be handled as normal waste: landfilled, recycled into consumer items, etc. Much low-level waste releases very low levels of radioactivity and is essentially considered radioactive waste because of its history. For example, according to the standards of the NRC, the radiation released by coffee is enough to treat it as low level waste. Overall, nuclear power produces far less waste material than fossil-fuel based power plants. Coal-burning plants are particularly noted for producing large amounts of radioactive ash due to concentrating naturally occurring radioactive material in the coal.

In addition, the nuclear industry fuel cycle produces many tons of depleted uranium (uranium from which the easily fissile U235 has been removed, leaving behind only U238). This material is much more concentrated than natural uranium ores, and must be disposed of. U238 is a very tough metal with several commercial uses, for example aircraft production and radiation shielding. In particular, depleted uranium is much sought after for making bullets and armor, as it has higher density than even lead. There has been some concern that this may be causing health problems in some groups exposed to this material excessively, such as tank crews.

The amounts of waste can be reduced in several ways. Both nuclear reprocessing and fast breeder reactors can reduce the amounts of waste and increase the amount of energy gained per fuel unit. Subcritical reactors or fusion reactors could greatly reduce the time the waste has to be stored [13]. Subcritical reactors may also be able to do the same to already existing waste. It has been argued that the best solution for the nuclear waste is above ground temporary storage since technology is rapidly changing. The current waste may well become valuable fuel in the future, particularly if it is not reprocessed, as in the U.S..

[edit] Economics

Opponents of nuclear power claim that any of the environmental benefits are outweighed by safety compromises and by the costs related to construction and operation of nuclear power plants, including costs for spent-fuel disposition and plant retirement. Proponents of nuclear power state that nuclear energy is the only power source which explicitly factors the estimated costs for waste containment and plant decommissioning into its overall cost, and that the quoted cost of fossil fuel plants is deceptively low for this reason.

A UK Royal Academy of Engineering report in 2004 looked at electricity generation costs from new plants in the UK. In particular it aimed to develop "a robust approach to compare directly the costs of intermittent generation with more dependable sources of generation". This meant adding the cost of standby capacity for wind, as well as carbon values up to £30 (€45.44) per tonne CO2 for coal and gas. Wind power was calculated to be more than twice as expensive as nuclear power. Without a carbon tax, the cost of production through coal, nuclear and gas ranged £0.22-0.26/kWh and coal gasification was £0.32/kWh. When carbon tax was added (up to £0.25) coal came close to onshore wind (including back-up power) at £0.54/kWh - offshore wind is £0.72/kWh. Nuclear power remained at £0.23/kWh either way, as it produces negligible amounts of CO2. Nuclear figures included decommissioning costs. [14].

[edit] Capital costs

Generally, a single nuclear power plant is significantly more expensive to build than a single steam-based coal-fired plant. A coal plant is itself more expensive to build than a single natural gas-fired combined-cycle plant. Although the cost per megawatt for a nuclear power plant is comparable to a coal-fired plant and less than a natural gas plant, the smallest nuclear power plant that can be built is much larger than the smallest natural gas power plant, making it possible for a utility to build additional natural gas plants in smaller increments, and in areas of low power consumption.

In many countries, licensing, inspection and certification of nuclear power plants has added delays and construction costs to their construction. In the U.S. many restrictions were put in place after the Three Mile Island partial meltdown. Building gas-fired or coal-fired plants does not have these problems. Because a power plant does not yield profits during construction, longer construction times translate directly into higher interest charges on borrowed construction funds. However, the regulatory processes for siting, licensing, and constructing have been standardized since their introduction, to make construction of newer (inherently safer) designs more attractive to utility companies and their investors.

In Japan and France, construction costs and delays are significantly less because of streamlined government licensing and certification procedures. In France, one model of reactor was type-certified, using a safety engineering process similar to the process used to certify aircraft models for safety. That is, rather than licensing individual reactors, the regulatory agency certified a particular design and its construction process to produce safe reactors. U.S. law permits type-licensing of reactors, but no type license has ever been issued by a U.S. nuclear regulatory agency.

To encourage development of nuclear power, under the Nuclear Power 2010 Program the U.S. Department of Energy (DOE) has offered interested parties the opportunity to introduce France's model for licensing and to subsidize up to 50% of the construction cost overruns due to delays. Several applications were made, and two sites have been chosen to receive new plants.

[edit] Operating costs

In the U.S. coal and nuclear power plants must operate more cheaply than natural gas plants to be built. In general, coal and nuclear plants have the same operating costs (operations and maintenance plus fuel costs). However, nuclear and coal differ in the source of those costs. Nuclear has lower fuel costs but higher operating and maintenance costs than coal. In recent times in the United States these operating costs have not been low enough for nuclear to repay its high investment costs. Thus new nuclear reactors have not been built in the United States. Coal's operating cost advantages have only rarely been sufficient to encourage the construction of new coal based power generation. Around 90 to 95 percent of new power plant construction in the United States has been natural gas-fired. These numbers exclude capacity expansions at existing coal and nuclear units.

To be competitive in the current market, both the nuclear and coal industries must reduce new plant investment costs and construction time. The burden is clearly greater for nuclear producers than for coal producers, because investment costs are higher for nuclear plants, which also have the same operating costs. Operation and maintenance costs are particularly important because they represent a large portion of costs for nuclear power.

One of the primary reasons for the uncompetitiveness of the nuclear industry has been the reluctance of the U.S. government to tax carbon emissions which cause global warming. Taxing the negative externalities of coal and gas consumption (carbon emissions) may increase the competitiveness of nuclear industry. The U.S. government rejected the Kyoto protocol which encourages governments to take similar steps in promoting the use of non-fossil fuels.

[edit] Subsidies

The subsidies for nuclear power are often criticized by opponents. However, competing energy sources also receive subsidies. Fossil fuels receive large direct and indirect subsidies, like tax benefits and not having to pay for their pollution [15]. Renewables receive large direct production subsidies and tax breaks in many nations [16].

Energy research and development (R&D) for nuclear power has and continues to receive much larger state subsidies than R&D for renewable energy or fossil fuels. However, today most of this takes places in Japan and France: in most other nations renewable R&D get more money. In the U.S., public research money for nuclear fission declined from 2179 to 35 million dollars between 1980 to 2000 [17] - however, in order to restart the industry, the next six U.S. reactors will receive subsidies equal to those of renewables and, in the event of cost overruns due to delays, at least partial compensation for the overruns (see Nuclear Power 2010 Program).

According to the DOE, insurance for nuclear or radiological incidents in the U.S., is subsidized [18] by the Price-Anderson Nuclear Industries Indemnity Act - in July 2005, Congress extended this Act to newer facilities. In the UK, the Nuclear Installations Act of 1965 governs liability for nuclear damage for which a UK nuclear licensee is responsible. The Vienna Convention on Civil Liability for Nuclear Damage puts in place an international framework for nuclear liability.

[edit] Other economic issues

Nuclear Power plants tend to be most competitive in areas where no other resources are readily available - France, most notably, has almost no native supplies of fossil fuels [19]. The province of Ontario, Canada is already using all of its best sites for hydroelectric power, and has minimal supplies of fossil fuels, so a number of nuclear plants have been built there. India too has few resources and is building new nuclear plants. Conversely, in the United Kingdom, according to the government's Department Of Trade And Industry, no further nuclear power stations are to be built, due to the high cost per unit of nuclear power, compared to fossil fuels [20]. However, the British government's chief scientific advisor David King reports that building one more generation of nuclear power plants may be necessary [21]. China tops the list of planned new plants, due to its rapidly expanding economy and fervent construction in many types of energy projects [22].

Most new gas-fired plants are intended for peak supply. The larger nuclear and coal plants cannot quickly adjust their instantaneous power production, and are generally intended for baseline supply. The market price for baseline power has not increased as rapidly as that for peak demand. Some new experimental reactors, notably pebble bed modular reactors, are specifically designed for peaking power.

Any effort to construct a new nuclear facility around the world, whether an older design or a newer experimental design, must deal with NIMBY objections. Given the high profile of both the Three Mile Island accident and Chernobyl disaster, few municipalities welcome a new nuclear reactor, processing plant, transportation route, or experimental nuclear burial ground within their borders, and many have issued local ordinances prohibiting the development of nuclear power. However, a few U.S. areas with nuclear units are campaigning for more (see Nuclear Power 2010 Program).

[edit] Serious accidents which have occurred

[edit] The Chernobyl disaster

The Chernobyl disaster was a major accident at the Chernobyl Nuclear Power Plant on April 26, 1986, consisting of an explosion at the plant and subsequent radioactive contamination of the surrounding geographic area. The power plant is located at near Pripyat, Ukraine, Soviet Union. It is regarded as the worst accident ever in the history of nuclear power. A plume of radioactive fallout drifted over parts of the western Soviet Union, Eastern and Western Europe, Scandinavia, the UK, Ireland and eastern North America. Large areas of Ukraine, Belarus, and Russia were badly contaminated, resulting in the evacuation and resettlement of over 336,000 people. About 60% of the radioactive fallout landed in Belarus, according to official post-Soviet data.[1]

The accident raised concerns about the safety of the Soviet nuclear power industry, slowing its expansion for a number of years, while forcing the Soviet government to become less secretive. The now-independent countries of Russia, Ukraine, and Belarus have been burdened with the continuing and substantial decontamination and health care costs of the Chernobyl accident. It is difficult to tally accurately the number of deaths caused by the events at Chernobyl, as the Soviet-era cover-up made it difficult to track down victims. Lists were incomplete, and Soviet authorities later forbade doctors to cite "radiation" on death certificates. Most of the expected long-term fatalities, especially those from cancer, have not yet actually occurred, and will be difficult or even impossible to attribute specifically to the accident.

[edit] The Three Mile Island accident

Three Mile Island Nuclear Generating Station consisted of two pressurized water reactors manufactured by Babcock & Wilcox each inside its own containment building and connected cooling towers. TMI-2, which suffered a partial meltdown, is in the background.
Three Mile Island Nuclear Generating Station consisted of two pressurized water reactors manufactured by Babcock & Wilcox each inside its own containment building and connected cooling towers. TMI-2, which suffered a partial meltdown, is in the background.

On March 28, 1979, the Unit 2 nuclear power plant (a pressurized water reactor manufactured by Babcock & Wilcox) on the Three Mile Island Nuclear Generating Station in Dauphin County, Pennsylvania near Harrisburg suffered a partial core meltdown.

The Three Mile Island accident was the worst accident in American commercial nuclear power generating history, even though it led to no deaths or injuries to plant workers or members of the nearby community.[2]

The accident unfolded over the course of five tense days, as a number of agencies at local, state and federal level tried to diagnose the problem and decide whether or not the on-going accident required a full emergency evacuation of the population. The full details of the accident were not discovered until much later. In the end, the reactor was brought under control. Although approximately 25,000 people lived within five miles of the island at the time of the accident,[3] no identifiable injuries due to radiation occurred, and a government report concluded that "the projected number of excess fatal cancers due to the accident... is approximately one". But the accident had serious economic and public relations consequences, and the cleanup process was slow and costly. It also furthered a major decline in the public popularity of nuclear power, exemplifying for many the worst fears about nuclear technology and, until the Chernobyl disaster seven years later, it was considered the world's worst civilian nuclear accident.

[edit] Windscale fire

On October 10, 1957, the graphite core of a British nuclear reactor at Windscale, Cumbria, caught fire, releasing substantial amounts of radioactive contamination into the surrounding area. The event, known as the Windscale fire, was considered the world's worst nuclear accident until the Three Mile Island accident in 1979.

The fire itself released an estimated 20,000 curies (700 terabecquerels) of radioactive material into the nearby countryside. Of particular concern was the radioactive isotope iodine-131, which has a half-life of only 8 days but is taken up by the human body and stored in the thyroid. As a result, consumption of iodine-131 often leads to cancer of the thyroid.

No one was evacuated from the surrounding area, but there was concern that milk might be dangerously contaminated. Milk from about 500km² of nearby countryside was destroyed (diluted a thousand fold and dumped in the Irish Sea) for about a month.

[edit] Mayak accident

Mayak (Маяк, "beacon") is the name of a nuclear fuel reprocessing plant between the towns of Kasli and Kyshtym (also transliterated Kishtym or Kishtim) 150 km northwest of Chelyabinsk in Russia. Working conditions at Mayak resulted in severe health hazards and many accidents, [23] with a serious accident occurring in 1957.

The 1957 accident occurred when the failure of the cooling system for a tank storing tens of thousands of tons of dissolved nuclear waste resulted in a non-nuclear explosion having a force estimated at about 75 tons of TNT (310 gigajoules), which released some 20 MCi (740 petabecquerels) of radiation. See list of military nuclear accidents and [24]. Subsequently, at least 200 people died of radiation sickness, 10,000 people were evacuated from their homes, and 470,000 people were exposed to radiation.

[edit] Health impacts of Chernobyl and Three Mile Island

[edit] Chernobyl disaster

An abandoned village near Prypiat, close to Chernobyl
An abandoned village near Prypiat, close to Chernobyl

Following the Chernobyl disaster of 1986, two hundred people were hospitalized immediately, of whom 31 died (28 of them died from acute radiation exposure) [citation needed]. Most of these were fire and rescue workers trying to bring the accident under control, who were not fully aware of how dangerous the radiation exposure (from the smoke) was (for a discussion of the more important isotopes in fallout see fission products). 135,000 people were evacuated from the area, including 50,000 from Pripyat. Health officials from the Nuclear Energy Agency have predicted that over the next 70 years there will be a 0.01% increase in cancer rates above the base rate in much of the population that was exposed to the 5–12 (depending on source) EBq of radioactive contamination released from the reactor. So far three people have died of thyroid cancer as a result of the accident.[4]

Contamination from the Chernobyl accident was not evenly spread across the surrounding countryside, but scattered irregularly depending on weather conditions. Reports from Soviet and Western scientists indicate that Belarus received about 60% of the contamination that fell on the former Soviet Union. However, the TORCH 2006 report stated that half of the volatile particles had landed outside Ukraine, Belarus and Russia. A large area in Russia south of Bryansk was also contaminated, as were parts of northwestern Ukraine (see Chernobyl disaster effects article).

Aside from the immediate effects of the Chernobyl accident, there is continuing impact from soils containing radioactivity in Ukraine and Belarus (since, according to the Linear no-threshold model, there is no level of radiological exposure which does not cause cancers in some portion of the exposed population [25], however, the Linear no-threshold model is itself disputed.). For this reason a Zone of alienation was established around the Chernobyl plant.

[edit] Three Mile Island accident

The full damage to the Three Mile Island reactor core was not known for many years after the accident.
The full damage to the Three Mile Island reactor core was not known for many years after the accident.

The scientific community continues to be split into two camps over the aftermath of the Three Mile Island accident. One camp believes that no member of the public was injured by the accident. The other camp puts forth the position that the dosimeters that were placed around the plant were inadequate and that undetected plumes passed between the offsite LCD dosimeters. Proponents of high offsite exposures have pointed to the fogging of film in stores in the area as evidence. However, the only documented contamination to the wild food chain was presented in a paper in the Health Physics Journal authored by R. William Field and colleagues reporting elevated levels of radiaoactive Iodine in meadow vole thyroids.

"The average radiation dose to people living within ten miles of the plant was estimated to be 8 - 30 millirem (mrem), and no more than 100 mrem to any single individual. Eight millirem is about equal to a chest X-ray, and 100 millirem is about a third of the average background level of radiation received by US residents in a year."[5][6]

There have been many studies and none have detected a conclusive link between low level exposure and cancer increases. [26] In reality, the epidemiology studies did not have adequate power to detect an association if the off-site release estimates were correct. Nonetheless, "to this day [late 2004], Wing's article remains the only one to present original health data supporting a link between Three Mile Island radiation exposure and cancer."[7] R. William Field has pointed out in a 2005 paper in Radiation Protection Dosimetry that the counties surrounding Three Mile Island have the highest regional radon concentrations in the nation. As compared to the estimated 30 mrem dose from the accident, radon imparts doses on the order of 16,000 mrem to the bronchial epithelium to the average individual in the vicinity of Three Mile Island. Field pointed out that the studies performed by Steven Wing and others have failed to consider this important source of radiation exposure as a confounder in the epidemiological results.

A class action lawsuit alleging that the accident caused health effects was rejected by Harrisburg U.S. District Court Judge Sylvia Rambo. The appeal of the decision in front of U.S. Third Circuit Court of Appeals has also failed. [27]

[edit] Concerns about nuclear power

Opponents of nuclear power such as Greenpeace, argue against its use due to issues like the long term problems of storing radioactive waste, the potential for severe radioactive contamination by an accident, and the possibility that its use will lead to the proliferation of nuclear weapons. They point to the chequered history of nuclear power and its continual procession of nuclear accidents, from the 1950s to the present day. According to the Supreme Court of the United States in 1978, comprehensive testing and study have failed to remove the risk of a major nuclear accident resulting in extensive damage [28] (however, since then each US plant has undergone an Individual Plant Examination process using Probabilistic Risk Assessment to quantify the risk and identify and address high-risk areas - see NUREG-1150).

To highlight what they believe are the risks, opponents quote the situation in the United States, where under the Price-Anderson Nuclear Industries Indemnity Act corporations requested and were granted immunity beyond (in 2005) $10 billion (all the available insurance plus pool monies combined) from civil liability (including from possible criminal behavior, although that would be subject to criminal prosecution) from a nuclear incident which causes harm to the public. Beyond the $10 billion, Congress is required to act.

Proponents argue that the risks are small and that fear has been the single largest obstacle to the widespread use of nuclear power. They believe that nuclear power or coal are currently the only realistic large scale energy sources that would be able to replace oil and natural gas after a peak in global oil and gas production has been reached (see peak oil). Coal currently contributes significantly to problems like global warming, acid rain, various diseases due to airborne pollution, and the storage of large amounts of ash. Contrary to popular belief, coal power actually results in more radioactive waste being released into the environment than nuclear power [29].

[edit] Accident or attack

Main article: Nuclear safety

Opponents argue that a major disadvantage of the use of nuclear reactors is the threat of another nuclear accident or terrorist attack and the possible resulting exposure to radiation. Proponents argue that the potential for a meltdown, as in the Chernobyl disaster is very small due to the care taken in designing adequate safety systems, and that the nuclear industry has much better statistics regarding humans deaths from occupational accidents than coal or hydropower [30]. However, the Chernobyl disaster caused great negative health, economic, and psychological effects in a widespread area. The accident at Chernobyl was caused by a combination of the faulty RBMK reactor design, the lack of a containment building, poorly trained operators, and a non-existent safety culture. The RBMK design, unlike nearly all designs used in the Western world, featured a positive void coefficient, meaning that a malfunction could result in ever-increasing generation of heat and radiation until the reactor was breached. [31] Even with the Three Mile Island accident, the most severe civilian nuclear accident in the Western world, the reactor vessel and containment building were never breached so that very little radiation was released into the environment.

Opponents of nuclear power express concerns that nuclear waste is not well protected, and that it can be released in the event of terrorist attack, quoting a 1999 Russian incident where workers were caught trying to sell 5 grams of radioactive material on the open market [32], or the incident in 1993 where Russian workers were caught selling 4.5 kilograms of enriched uranium [33][34][35] . The UN has since called upon world leaders to improve security in order to prevent radioactive material falling into the hands of terrorists [36], leading to the guarding of nuclear shipments by thousands of police [37]. (Other energy sources, such as hydropower plants and liquified natural gas tankers, are more vulnerable to accidents and attacks) Proponents of nuclear power contend, however, that nuclear waste is already well protected, and state their argument that there has been no accident involving any form of nuclear waste from a civilian program worldwide. In addition, they point to large studies carried out by NRC and other agencies that tested the robustness of both reactor and waste fuel storage, and found that they should be able to sustain a terrorist attack comparable to the September 11 terrorist attacks [38]. Spent fuel is usually housed inside the reactor containment building [39].

According to the Nuclear Regulatory Commission, 20 American States have requested stocks of potassium iodide which the NRC suggests should be available for those living within 10 miles of a nuclear power plant in the unlikely event of a severe accident.[40].

[edit] By reactor type

Currently all commercial nuclear reactors are based on nuclear fission, and are considered problematic by some for their safety and health risks. Conversely, some consider nuclear power to be a safe and pollution-free method of generating electricity, despite the serious accidents which have occurred.

[edit] BWR
Main article: Boiling water reactor

[edit] PWR
Main article: Pressurized water reactor

[edit] Pebble bed reactor
Main article: Pebble bed reactor

Several critics of pebble bed reactors have claimed that encasing the fuel in potentially flammable graphite poses a hazard. The reactor's use of an inert gas as a coolant nullifies this issue.

Additionally, some designs for pebble bed reactors lack a containment building, potentially making such reactors more vulnerable to outside attack and allowing radioactive material to spread in the case of an explosion. However, an explosion would most likely be caused by an external factor, as the design does not suffer from the steam-explosion vulnerability of water-cooled reactors.

Since the fuel is contained in graphite pebbles, the actual volume of radioactive waste is greater, although the waste tends to be less hazardous. Defects in the production of pebbles may also cause problems.

Critics also often point out an accident in Germany in 1986, which involved a jammed pebble. This accident released radiation into the surrounding area, and led to a shutdown of the research program by the West German government.

[edit] Air pollution

Non-radioactive water vapour is the significant operating emission from nuclear power plants.[41] Fission produces gases such as iodine-131 or Xenon-133. These primarily remain within the fuel rods, but with some postulated fuel failure, small amounts of the gases can be released in to the reactor coolant. The chemical control systems isolate the radioactive gases which have to be stored on-site for several half-lives until they have decayed to safe levels. Iodine-131 and Xenon-133 have halflives of 8.0 and 5.2 days respectively, and thus have to be stored for a few months to decay to safe levels.

Nuclear generation does not directly produce sulfur dioxide, nitrogen oxides, mercury or other pollutants associated with the combustion of fossil fuels (pollution from fossil fuels is blamed for many deaths each year in the U.S. alone [42]) It also does not directly produce carbon dioxide or methane, which has led some environmentalists to advocate increased reliance on nuclear energy as a means to reduce greenhouse gas emissions (which contribute to global warming).

Like any power source (including renewables like wind and solar energy), the facilities to produce and distribute the electricity require energy to build and subsequently decommission. This includes both the energy expenditure required to produce the facilities, as well as other processes which contribute to global warming. For example, the manufacture of cement results in substantial direct emissions of carbon dioxide, caused when calcium carbonate is heated, producing lime and carbon dioxide. [43] Mineral ores must be mined, milled and processed to produce nuclear fuel. These processes are either directly powered by diesel and gasoline engines, or draw electricity from the power grid, most of which is derived from fossil fuels. Life cycle analyses assess the amount of energy consumed by these processes (given today's mix of energy resources) and calculate, over the lifetime of a nuclear power plant, the amount of greenhouse emissions saved (related to the amount of electricity produced by the plant) vs. the amount of greenhouse emissions used (related to construction and fuel acquisition).

Several life cycle analyses show similar emissions per kilowatt-hour from nuclear power and from renewables such as wind power. According to one life cycle study by van Leeuwen and Smith from 2001–2005, carbon dioxide emissions from nuclear power per kilowatt hour could range from 20% to 120% of those for natural gas-fired power stations depending on the availability of high grade ores. [44] The study was critiqued by World Nuclear Association (WNA), rebutted in 2003, then dismissed by the WNA in 2006 based on its own life-cycle-energy calculation (with comparisons).[8]

In 2006, a UK government advisory panel, The Sustainable Development Commission, concluded that if the UK's existing nuclear capacity were doubled, it would provide an 8% decrease in total UK CO2 emissions by 2035. This can be compared to the country's goal to reduce greenhouse gas emissions by 60 % by 2050. As of 2006, the UK government was to publish its official findings later in the year.[9][10]

On 21 September 2005 the Oxford Research Group published a report, in the form of a memorandum to a committee of the British House of Commons, which argued that, while nuclear plants may not generate carbon dioxide while they operate, the other steps necessary to produce nuclear power, including the mining of uranium and the storing of waste, result in substantial amounts of carbon dioxide pollution.[11]

[edit] Waste heat in water systems

Nuclear reactors require water to keep the reactor cool. The process of extracting energy from a heat source, called the Rankine cycle, requires the steam to be cooled down. Rivers are the most common source of cooling water, as well as the destination for waste heat. The temperature of exhaust water must be regulated to avoid killing fish; long-term impact of hotter-than-natural water on ecosystems is an environmental concern.

The need to regulate exhaust temperature also limits generation capacity. On extremely hot days, which is when demand can be at its highest, the capacity of a nuclear plant may go down because the incoming water is warmer to begin with (and is thus less effective as a coolant, per unit volume). This was a significant factor in the European heat wave of 2003. Engineers consider this in making better power plant designs because increased cooling capacity will increase costs.

[edit] Health effect on population near nuclear plants

Most of the human exposure to radiation comes from natural background radiation. Most of the remaining exposure comes from medical procedures. Several large studies in the US, Canada, and Europe have found no evidence of any increase in cancer mortality among people living near nuclear facilities. For example, in 1990, the National Cancer Institute (NCI) of the National Institutes of Health announced that a large-scale study, which evaluated mortality from 16 types of cancer, found no increased incidence of cancer mortality for people living near 62 nuclear installations in the United States. The study showed no increase in the incidence of childhood leukemia mortality in the study of surrounding counties after start-up of the nuclear facilities. The NCI study, the broadest of its kind ever conducted, surveyed 900,000 cancer deaths in counties near nuclear facilities.

However, in Britain there are elevated childhood leukemia levels near some industrial facilities, particularly near Sellafield, where children living locally are ten times more likely to contract the cancer. The reasons for these increases, or clusters, are unclear, but one study of those near Sellafield has ruled out any contribution from nuclear sources.

Apart from anything else, the levels of radiation at these sites are orders of magnitude too low to account for the excess incidences reported. One explanation is viruses or other infectious agents being introduced into a local community by the mass movement of migrant workers. Likewise, small studies have found an increased incidence of childhood leukemia near some nuclear power plants has also been found in Germany [45] and France [46]. Nonetheless, the results of larger multi-site studies in these countries invalidate the hypothesis of an increased risk of leukaemia related to nuclear discharge. The methodology and very small samples in the studies finding an increased incidence has been criticized. [47] [48] [49] [50]. Also, one study focussing on Leukaemia clusters in industrial towns in England indicated a link to high-capacity electricity lines suggesting that the production or distribution of the electricity, rather than the nuclear reaction, may be a factor.

[edit] Nuclear proliferation

For more details on this topic, see Nuclear proliferation.

Opponents of nuclear power point out that nuclear technology is often dual-use, and much of the same materials and knowledge used in a civilian nuclear program can be used to develop nuclear weapons. This concern is known as nuclear proliferation and is a major reactor design criterion.

The military and civil purposes for nuclear energy are intertwined in most countries with nuclear capabilities. In the US for example the first goal of the Department of Energy is "To protect our national security by applying advanced science and nuclear technology to the Nation’s defense." [51]

The enriched uranium used in most nuclear reactors is not concentrated enough to build a bomb. Most nuclear reactors run on 4% enriched uranium; Little Boy used 90% enriched uranium; while lower enrichment levels could be used the minimum bomb size would rapidly become infeasibly large as the level was decreased. However, the technology used to enrich uranium for power generation could be used to make the highly enriched uranium needed to build a bomb. In addition, designs such as CANDU can be more easily misused to generate plutonium suitable for bomb making. It is believed that the nuclear programs of India and Pakistan used CANDU reactors to produce fissionable materials for their weapons, however, this is a myth. India used a research reactor named CIRUS, based on the Canadian NRX design, which was donated by Canada under the condition that it not be used for weapons production[52]. Pakistan is believed to have produced the material for its weapons from an indigenous enrichment program [53].

To prevent weapons proliferation, safeguards on nuclear technology were published in the Nuclear Non-Proliferation Treaty (NPT) and monitored since 1968 by the International Atomic Energy Agency (IAEA). Nations signing the treaty are required to report to the IAEA what nuclear materials they hold and their location. They agree to accept visits by IAEA auditors and inspectors to verify independently their material reports and physically inspect the nuclear materials concerned to confirm physical inventories of them in exchange for access to nuclear materials and equipment on the global market.

Several states did not sign the treaty and were able to use international nuclear technology (often procured for civilian purposes) to develop nuclear weapons (India, Pakistan, Israel, and South Africa). South Africa has since signed the NPT, and now holds the distinction of being the only known state to have indigenously produced nuclear weapons, and then verifiably dismantled them[54]. Of those who have signed the treaty and received shipments of nuclear paraphernalia, many states have either claimed to or been accused of attempting to use supposedly civilian nuclear power plants for developing weapons, including Iran and North Korea. Certain types of reactors are more conducive to producing nuclear weapons materials than others, and a number of international disputes over proliferation have centered on the specific model of reactor being contracted for in a country suspected of nuclear weapon ambitions.

New technology, like SSTAR, may lessen the risk of nuclear proliferation by providing sealed reactors with a limited self-contained fuel supply and with restrictions against tampering.

One possible obstacle for expanding the use of nuclear power might be a limitated supply of uranium ore, without which it would become necessary to build and operate breeder reactors. However, at current usage there is sufficient uranium for an extended period - "In summary, the actual recoverable uranium supply is likely to be enough to last several hundred (up to 1000) years, even using standard reactors." [55] (see Fuel resources above). Breeder reactors have been banned in the US since President Carter's administration prohibited reprocessing because of what it regarded as the unacceptable risk of proliferation of weapon grade materials.

Some proponents of nuclear power agree that the risk of nuclear proliferation may be a reason to prevent nondemocratic developing nations from gaining any nuclear technology but argue that this is no reason for democratic developed nations to abandon their nuclear power plants. Especially since it seems that democracies never make war against each other (See the democratic peace theory).

Proponents also note that nuclear power (like some other power sources) provides steady energy at a consistent price without competing for energy resources from other countries, something that may contribute to wars.

[edit] Links with military

Original impetus for development of nuclear power came from the military nuclear programmes, including the early designs of power reactors that were developed for nuclear submarines. In many countries nuclear and civilian nuclear programmes are linked, at least by common research projects and through agencies such as the US DOE and French CEA. Fear of nuclear proliferation (see above) though links with military is the declared reason for opposition from the US, Germany, France, the United Kingdom and others to nuclear power development in Iran and North Korea.

[edit] List of atomic energy groups

[edit] List of environmental organizations

[edit] References

[edit] See also

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