核電存廢問題

核電存廢問題是人类社会对核能發電使用的持续的争议性讨论。

然而，核電的存廢政策各地不同，如歐洲許多國家近來逐漸地走向放棄核能發電，德國更宣佈在2022年前關閉所有的核電站；而開發中國家則較傾向使用核能發電。

核電簡史

第一个成功的核裂变实验装置在1938年的柏林被德国科学家奥托·哈恩、莉泽·迈特纳和弗瑞兹·斯特拉斯曼制成。

在第二次世界大战中，一些国家致力于研究核能的利用，它们首先研究的是核反应堆。1942年12月2日，恩里科·费米在芝加哥大学建成了第一个完全自主的链式核反应堆，在他的研究基础上建立的反应堆被用来制造轰炸了长崎的原子弹“胖子”中的钚。在这个时候，一些国家也在研究核能，它们的研究重点是核武器，但同时也进行民用核能的研究。

1951年12月20日人类首次用核反应堆产生出了电能，这个核反应堆位于爱达荷州Arco的EBR-I试验增殖反应堆，它最初向外输出的功率为100kW。

1954年6月27日，世界上第一个为电网提供电力的核电站在苏联的欧伯宁斯克开始运行。这个反应堆使用了石墨来控制核反应并用水来冷却，功率为5兆瓦。全世界第一个投入商业运营的核反应堆是位于英格兰設菲尔德的Calder Hall，它于1956年开始运行。它有一个Magnox型反应堆，最初的输出功率为 50兆瓦，后来提高到了200兆瓦。 宾夕法尼亚州码头市的一个压水型反应堆是美国第一个投入商业运营的反应堆。

在20世纪后半叶，一些反对核能的运动开始兴起，它们担心的是核事故和核辐射，还反对生产，运输和储藏核废料。1979年的三哩岛核泄漏事故和1986年的切尔诺贝利核事故成为了许多国家停止建造新核电站的关键理由。澳大利亚于1978年，瑞典于1980年，意大利于1987年都对建造核电站的问题发动了全民公投，同时爱尔兰的核能反对者成功地阻止了在該處核能计划的实施。但布鲁金斯学会表示，美国政府没有批准新核电站的建造主要是由于经济原因，而非安全问题。

論點簡要

支持核能的理由

下為巴瑞‧布魯克在2010年出版的《為什麼對為什麼：核能發電》（Why vs. Why: Nuclear Power）一書中提出的七項支持核能發電理由：

• 再生能源與能源效率（energy efficiency）不能解決能源與氣候變遷的問題。
• 核燃料是近於無限的且能提供大量的能源。
• 新科技能解決「核廢料」問題。
• 核能發電是最安全的能源選項。
• 更進步的核能發電能加強全球社會的安全。
• 核電的真實花費低於化石燃料或可再生能源。
• 核能發電可引領「清潔能源」的革命。

反對核能的理由

下為伊恩‧羅威在2010年出版的《為什麼對為什麼：核能發電》一書中提出的七項支持核能發電理由：

• 核能發電對氣候變遷不是一個夠快速的回應。
• 核能發電太貴了。
• 對基載電能的需求被誇大了。
• 核廢料問題依舊是無解的問題。
• 核能發電會增加核戰的風險。
• 核能發電有安全問題。
• 人類對能源有更好的替代方案。

論點

供給的能源

Many studies have documented how nuclear power plants generate 16% of global electricity, but provide only 6.3% of energy production and 2.6% of final energy consumption. This mismatch stems mainly from the poor consumption efficiency of electricity compared to other energy carriers, and the transmission losses associated with nuclear plants which are usually situated far away from sources of demand.

However The transmission losses associated with Nuclear plants, or indeed Hydroelectric plants, which are also usually situated far away from the sources of demand, are not high, as they use HVDC cables which have losses of just 3% over 1000 km. Similarly Nuclear power is not alone in appearing small when representing World energy consumption which includes non-electric fossil fuel heating and transport fuel, which Coal and Oil dominate. In 2008 world energy supply by power source was - oil 33.5%, coal 26.8%, gas 20.8% (fossil 81%), 'Other'(Geothermal power, peat, biofuels, solar, wind, etc.) 10.4%, nuclear 5.8% and Hydro 2.3%. Oil was the most popular energy fuel. Oil and coal combined represented over 60% of the world energy supply in 2008.

能源保障

能源保障（Energy Security）問題不該與核電安全混為一談，能源保障指的是能源的燃料是否能安全提供的問題。

For some countries, nuclear power affords energy independence. Nuclear power has been relatively unaffected by embargoes, and uranium is mined in countries willing to export, including Australia and Canada. However, countries now responsible for more than 30% of the world’s uranium production: Kazakhstan, Namibia, Niger, and Uzbekistan, are politically unstable.

Reserves from existing uranium mines are being rapidly depleted, and one assessment from the IAEA showed that enough high-grade ore exists to supply the needs of the current reactor fleet for only 40–50 years. Expected shortfalls in available fuel threaten future plants and contribute to volatility of uranium prices at existing plants. Uranium fuel costs have escalated in recent years, which negatively impacts on the viability of nuclear projects.

According to a Stanford study, fast breeder reactors have the potential to provide power for humans on earth for billions of years, making this source sustainable. But "because of the link between plutonium and nuclear weapons, the potential application of fast breeders has led to concerns that nuclear power expansion would bring in an era of uncontrolled weapons proliferation". Thorium-fuelled thermal breeder reactors such as LFTR also have the potential to satisfy the global energy needs for hundreds of thousands of years, while offering high proliferation resistance compared to uranium-fuelled breeders.

可靠性

In 2010, the worldwide average capacity factor was 80.1%. In 2005, the global average capacity factor was 86.8%, the number of SCRAMs per 7,000 hours critical was 0.6, and the unplanned capacity loss factor was 1.6%. Capacity factor is the net power produced divided by the maximum amount possible running at 100% all the time, thus this includes all scheduled maintenance/refueling outages as well as unplanned losses. The 7,000 hours is roughly representative of how long any given reactor will remain critical in a year, meaning that the scram rates translates into a sudden and unplanned shutdown about 0.6 times per year for any given reactor in the world. The unplanned capacity loss factor represents amount of power not produced due to unplanned scrams and postponed restarts.

The World Nuclear Association argues that: "Obviously sun, wind, tides and waves cannot be controlled to provide directly either continuous base-load power, or peak-load power when it is needed,..." "In practical terms non-hydro renewables are therefore able to supply up to some 15–20% of the capacity of an electricity grid, though they cannot directly be applied as economic substitutes for most coal or nuclear power, however significant they become in particular areas with favourable conditions." "If the fundamental opportunity of these renewables is their abundance and relatively widespread occurrence, the fundamental challenge, especially for electricity supply, is applying them to meet demand given their variable and diffuse nature. This means either that there must be reliable duplicate sources of electricity beyond the normal system reserve, or some means of electricity storage." "Relatively few places have scope for pumped storage dams close to where the power is needed, and overall efficiency is less than 80%. Means of storing large amounts of electricity as such in giant batteries or by other means have not been developed."

According to Benjamin K. Sovacool, most studies critiquing solar and wind energy look only at individual generators and not at the system wide effects of solar and wind farms. Correlations between power swings drop substantially as more solar and wind farms are integrated (a process known as geographical smoothing) and a wider geographic area also enables a larger pool of energy efficiency efforts to abate intermittency.

Sovacool says that previously intermittent sources such as wind and solar can displace nuclear resources. "Nine recent studies have concluded that the variability and intermittency of wind and solar resources becomes easier to manage the more they are deployed and interconnected, not the other way around, as some utilities suggest. This is because wind and solar plants help grid operators handle major outages and contingencies elsewhere in the system, since they generate power in smaller increments that are less damaging than unexpected outages from large plants".

According to a 2011 projection by the International Energy Agency, solar power generators may produce most of the world’s electricity within 50 years, with wind power, hydroelectricity and biomass plants supplying much of the remaining generation. "Photovoltaic and concentrated solar power together can become the major source of electricity". Renewable technologies can enhance energy security in electricity generation, heat supply, and transportation.

Amory Lovins explains that even large nuclear plants cannot supply continuous baseload electricity:

"All sources of electricity sometimes fail, differing only in how predictably, how often, how much, for how long, and why. Even the most reliable giant power plants are intermittent: "they fail unexpectedly in billion-watt chunks, often for long periods. In the United States, 132 nuclear plants were built, and 21% were permanently and prematurely closed due to reliability or cost problems, while another 27% have at least once completely failed for a year or more. The remaining U.S. nuclear plants produce approximately 90% of their full-time full-load potential, but even they are not fully dependable. Reliably operating nuclear plants must shut down, on average, for 39 days every 17 months for refueling and maintenance.

"To cope with such intermittence by both nuclear and centralized fossil-fuelled power plants, utilities must install a "reserve margin" of roughly 15% extra capacity, some of which must be continuously fuelled, spinning ready for instant use. Regions which depend heavily on nuclear power "are particularly at risk because drought, a serious safety problem, or a terrorist incident could close many plants simultaneously".

Lovins says that nuclear plants have an additional disadvantage: for safety, they must instantly shut down in a power failure, but for nuclear-physics reasons, they can’t be quickly restarted. For example, during the Northeast Blackout of 2003, nine perfectly operating U.S. nuclear units had to shut down. For the first three days after restart, when they were most needed, their output was below 3% of normal.

Since nuclear power plants are fundamentally heat engines, waste heat disposal becomes an issue at high ambient temperature. Droughts and extended periods of high temperature can "cripple nuclear power generation, and it is often during these times when electricity demand is highest because of air-conditioning and refrigeration loads and diminished hydroelectric capacity". In such very hot weather a power reactor may have to operate at a reduced power level or even shut down. In the 2006 European heat wave, a number of nuclear plants had to secure exemptions from regulations in order to discharge overheated water into the environment; several European nations were forced to reduce operations at some plants and take others offline and France, normally an electricity exporter, had to buy electricity on European spot market to meet demand. In 2009 in Germany, eight nuclear reactors had to be shut down simultaneously on hot summer days for reasons relating to the overheating of equipment or of rivers. Overheated discharge water has resulted in significant fish kills in the past, impacting livelihood and raising public concern.

經濟效益

New nuclear plants

主条目：Economics of new nuclear power plants

The economics of new nuclear power plants is a controversial subject, since there are diverging views on this topic, and multi-billion dollar investments ride on the choice of an energy source. Nuclear power plants typically have high capital costs for building the plant, but low direct fuel costs (with much of the costs of fuel extraction, processing, use and long term storage externalized). Therefore, comparison with other power generation methods is strongly dependent on assumptions about construction timescales and capital financing for nuclear plants. Cost estimates also need to take into account plant decommissioning and nuclear waste storage costs. On the other hand measures to mitigate global warming, such as a carbon tax or carbon emissions trading, may favor the economics of nuclear power.

In recent years there has been a slowdown of electricity demand growth and financing has become more difficult, which has an impact on large projects such as nuclear reactors, with very large upfront costs and long project cycles which carry a large variety of risks. In Eastern Europe, a number of long-established projects are struggling to find finance, notably Belene in Bulgaria and the additional reactors at Cernavoda in Romania, and some potential backers have pulled out. Where cheap gas is available and its future supply relatively secure, this also poses a major problem for nuclear projects.

Analysis of the economics of nuclear power must take into account who bears the risks of future uncertainties. To date all operating nuclear power plants were developed by state-owned or regulated utility monopolies where many of the risks associated with construction costs, operating performance, fuel price, and other factors were borne by consumers rather than suppliers. Many countries have now liberalized the electricity market where these risks, and the risk of cheaper competitors emerging before capital costs are recovered, are borne by plant suppliers and operators rather than consumers, which leads to a significantly different evaluation of the economics of new nuclear power plants.

Following the 2011 Fukushima Daiichi nuclear disaster, costs are likely to go up for currently operating and new nuclear power plants, due to increased requirements for on-site spent fuel management and elevated design basis threats.

Cost of decommissioning nuclear plants

Shutting down a nuclear plant is cited as an extremely expensive process by nuclear power critics, although the costs are usually covered by a component of price charged for electricity during operation. In the UK the Nuclear Decommissioning Authority has increased the overall cost for decommissioning nuclear plants from £57 billion in 2005 to £73 billion in 2008, according to the BBC, although this is heavily influenced by cleaning up the weapons development at Sellafield. However, the Parliamentary Public Accounts Committee was told in July 2008 that this cost could rise further and that it is almost impossible to come up with an accurate figure. Stabilising a plant and ensuring that it is safe is cited as an unknown cost by critics, claiming that decommissioning costs can massively increase the overall cost of nuclear energy.

Subsidies

Critics of nuclear power claim that it is the beneficiary of inappropriately large economic subsidies, taking the form of research and development, financing support for building new reactors and decommissioning old reactors and waste, and that these subsidies are often overlooked when comparing the economics of nuclear against other forms of power generation.

Nuclear power proponents argue that competing energy sources also receive subsidies. Fossil fuels receive large direct and indirect subsidies, such as tax benefits and not having to pay for the greenhouse gases they emit. Renewables receive proportionately large direct production subsidies and tax breaks in many nations, although in absolute terms they are often less than subsidies received by other sources.

Energy research and development (R&D) for nuclear power continues to receive large state subsidies. In the United States, nuclear receives more Federal R&D support than the renewables industry, however the impact of favorable tax incentives drives the total Federal support of the renewables industry to a level almost four times as high as that of the nuclear industry, despite all renewables (excluding hydroelectric, which receives no R&D funding) producing only 1/8 as much power as nuclear. In Europe, the FP7 research program has more subsidies for nuclear than for renewable and energy efficiency together, although over 70% of this is directed at the ITER fusion project. In the US, public research money for nuclear fission declined from 2,179 to 35 million dollars between 1980 and 2000.

A May 12, 2008 editorial in the Wall St. Journal stated, "For electricity generation, the EIA concludes that solar energy is subsidized to the tune of $24.34 per megawatt hour, wind $23.37 and 'clean coal' $29.81. By contrast, normal coal receives 44 cents, natural gas a mere quarter, hydroelectric about 67 cents and nuclear power $1.59." The impacts of prior subsidies, some of which may no longer be in effect, are not measured in the previous analysis. However, the Renewable Energy Policy Project stated that from 1947 to 1999, nuclear power was subsidized $145.4 billion, wind power $1.2 billion and solar $4.4 billion. From a megawatt hour basis, this translates into $12.45 per MWh produced for nuclear power, $36.47 for wind power and $511.63 for solar (1999 dollars).

A 2010 report by Global Subsidies Initiative compared relative subsidies of most common energy sources. It found that nuclear energy receives 1,7 US cents per kWh of energy it produces, compared to fossil fuels receiving 0,8 US cents per kWh, renewable energy receiving 5.0 US cents per kWh and biofuels receiving 5,1 US cents per kWh.

Indirect nuclear insurance subsidy

Kristin Shrader-Frechette has said "if reactors were safe, nuclear industries would not demand government-guaranteed, accident-liability protection, as a condition for their generating electricity". No private insurance company or even consortium of insurance companies "would shoulder the fearsome liabilities arising from severe nuclear accidents".

The potential costs resulting from a nuclear accident (including one caused by a terrorist attack or a natural disaster) are so great that no nuclear power plant would be built if the owner had to pay for liability insurance that fully covered these costs. The liability of owners of nuclear power plants in the U.S. is currently limited under the Price-Anderson Act (PAA). The Price-Anderson Act, introduced in 1957, was "an implicit admission that nuclear power provided risks that producers were unwilling to assume without federal backing". The Price-Anderson Act "shields nuclear utilities, vendors and suppliers against liability claims in the event of a catastrophic accident by imposing an upper limit on private sector liability". Without such protection, private companies were unwilling to be involved. No other technology in the history of American industry has enjoyed such continuing blanket protection.

The PAA was due to expire in 2002, and the former U.S. vice-president Dick Cheney said in 2001 that "nobody's going to invest in nuclear power plants" if the PAA is not renewed. The U.S. Nuclear Regulatory Commission (USNRC) concluded that the liability limits placed on nuclear insurance were significant enough to constitute a subsidy, but a quantification of the amount was not attempted at that time. Shortly after this in 1990, Dubin and Rothwell were the first to estimate the value to the U.S. nuclear industry of the limitation on liability for nuclear power plants under the Price Anderson Act. Their underlying method was to extrapolate the premiums operators currently pay versus the full liability they would have to pay for full insurance in the absence of the PAA limits. The size of the estimated subsidy per reactor per year was $60 million prior to the 1982 amendments, and up to $22 million following the 1988 amendments. In a separate article in 2003, Anthony Heyes updates the 1988 estimate of $22 million per year to $33 million (2001 dollars).

In case of a nuclear accident, should claims exceed this primary liability, the PAA requires all licensees to additionally provide a maximum of $95.8 million into the accident pool - totaling roughly $10 billion if all reactors were required to pay the maximum. This is still not sufficient in the case of a serious accident, as the cost of damages could exceed $10 billion. According to the PAA, should the costs of accident damages exceed the $10 billion pool, the remainder of the costs would be fully covered by the U.S. Government. In 1982, a Sandia National Laboratories study concluded that depending on the reactor size and 'unfavorable conditions' a serious nuclear accident could lead to property damages as high as $314 billion while fatalities could reach 50,000. A recent study found that if only this one relatively ignored indirect subsidy for nuclear power was converted to a direct subsidy and diverted to photovoltaic manufacturing, it would result in more installed power and more energy produced by mid-century compared to the nuclear case.

對環境的影響

The primary environmental impacts of nuclear power come from uranium mining, radioactive effluent emissions, and waste heat, as under normal generating conditions nuclear power does not produce greenhouse gas emissions [CO
2, NO
2] directly (although the nuclear fuel cycle produces them indirectly, though at much smaller rates than fossil fuels). Nuclear generation does not directly produce sulfur dioxide, nitrogen oxides, mercury or other pollutants associated with the combustion of fossil fuels. In 2008, The Economist stated that "nuclear reactors are the one proven way to make carbon-dioxide-free electricity in large and reliable quantities that does not depend (as hydroelectric and geothermal energy do) on the luck of the geographical draw." Many experts, some of whom consider themselves environmentalists, now believe that expanded nuclear generation is the only way to reduce green house gas emissions while providing for current and future electricity needs. However, this is disputed in the literature because of the basic thermodynamic limits to nuclear energy deployment.

Nuclear power plants produce electricity with about 66 g equivalent lifecycle carbon dioxide emissions per kWh, while renewable power generators produce electricity with 9.5-38 g carbon dioxide per kWh. A more recent, 2012 study by Yale University however revealed this Nuclear estimate to be too high, and instead the mean value from Nuclear power, depending on which Reactor design was analysed, produce from 11- 25 g/kW·h of total life cycle CO2 emissions

While nuclear power does not directly emit greenhouse gasses, over a facility's life cycle, emissions occur through plant construction, operation, uranium mining and milling, and plant decommissioning. Thus, if nuclear energy were used to rapidly replace existing energy sources there would be an energy cannibalism effect, which would impact the carbon neutral growth rate of the technology. A meta analysis of 103 life cycle studies by Benjamin K. Sovacool, found that nuclear power plants produce electricity with about 66 g equivalent lifecycle carbon dioxide emissions per kWh, while renewable power generators produce electricity with only 9.5-38 g carbon dioxide per kWh. This work on carbon emissions from nuclear power stations has been reviewed in Nature. A study done at the University of Wisconsin showed all non-fossil sources are roughly equal in reducing greenhouse-gas emissions.

Nuclear plants require more, but not significantly more, cooling water than fossil-fuel power plants due to their slightly lower generation efficiencies. Uranium mining can use large amounts of water — for example, the Roxby Downs mine in South Australia uses 35 million litres of water each day and plans to increase this to 150 million litres per day.

High-level radioactive waste

主条目：High-level radioactive waste management

Spent nuclear fuel stored underwater and uncapped at the Hanford site in Washington, USA.

The world's nuclear fleet creates about 10,000 metric tons of high-level spent nuclear fuel each year. High-level radioactive waste management concerns management and disposal of highly radioactive materials created during production of nuclear power. The technical issues in accomplishing this are daunting, due to the extremely long periods radioactive wastes remain deadly to living organisms. Of particular concern are two long-lived fission products, Technetium-99 (half-life 220,000 years) and Iodine-129 (half-life 15.7 million years), which dominate spent nuclear fuel radioactivity after a few thousand years. The most troublesome transuranic elements in spent fuel are Neptunium-237 (half-life two million years) and Plutonium-239 (half-life 24,000 years). Consequently, high-level radioactive waste requires sophisticated treatment and management to successfully isolate it from the biosphere. This usually necessitates treatment, followed by a long-term management strategy involving permanent storage, disposal or transformation of the waste into a non-toxic form.

Governments around the world are considering a range of waste management and disposal options, usually involving deep-geologic placement, although there has been limited progress toward implementing long-term waste management solutions. This is partly because the timeframes in question when dealing with radioactive waste range from 10,000 to millions of years, according to studies based on the effect of estimated radiation doses.

Since the fraction of a radioisotope's atoms decaying per unit of time is inversely proportional to its half-life, the relative radioactivity of a quantity of buried human radioactive waste would diminish over time compared to natural radioisotopes (such as the decay chain of 120 trillion tons of thorium and 40 trillion tons of uranium which are at relatively trace concentrations of parts per million each over the crust's 3 * 10¹⁹ ton mass). For instance, over a timeframe of thousands of years, after the most active short half-life radioisotopes decayed, burying U.S. nuclear waste would increase the radioactivity in the top 2000 feet of rock and soil in the United States (10 million km²) by ≈ 1 part in 10 million over the cumulative amount of natural radioisotopes in such a volume, although the vicinity of the site would have a far higher concentration of artificial radioisotopes underground than such an average.

Disposal of nuclear waste is often said to be the Achilles' heel of the nuclear industry. Presently, waste is mainly stored at individual reactor sites and there are over 430 locations around the world where radioactive material continues to accumulate. Experts agree that centralized underground repositories which are well-managed, guarded, and monitored, would be a vast improvement. There is an international consensus on the advisability of storing nuclear waste in deep underground repositories, but no country in the world has yet opened such a site.

Advocates of nuclear energy point out that high-level radioactive waste is not a fundamental issue for nuclear energy in general, but only for the conventional "once-through" light water reactors, which use only 0.6% of the energy contained in the uranium fuel, and discard the rest as high-level waste. Reactors such as Integral Fast Reactor or Liquid fluoride thorium reactor which "burn" almost all the actinides in the fuel have successfully operated. These reactors can extract almost all energy content of the fuel, and even consume nuclear waste from conventional reactors as fuel, turning liability into an asset. The resulting low-actinide waste reaches safe background radiation levels in just 300 years, compared to tens of thousands of years in case of high level waste from once-through LWR reactors.

核電意外與安全

車諾比事件

主条目：切尔诺贝利核事故

車諾比事件後，1996年在俄羅斯、白俄羅斯和烏克蘭三國境內的銫-137污染分佈概況。

The Chernobyl explosion was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine. An explosion and fire released large quantities of radioactive contamination into the atmosphere, which spread over much of Western USSR and Europe. It is considered the worst nuclear power plant accident in history, and is one of only two classified as a level 7 event on the International Nuclear Event Scale (the other being the Fukushima Daiichi nuclear disaster). The battle to contain the contamination and avert a greater catastrophe ultimately involved over 500,000 workers and cost an estimated 18 billion rubles, crippling the Soviet economy. The accident raised concerns about the safety of the nuclear power industry, slowing its expansion for a number of years.

UNSCEAR has conducted 20 years of detailed scientific and epidemiological research on the effects of the Chernobyl accident. Apart from the 57 direct deaths in the accident itself, UNSCEAR predicted in 2005 that up to 4,000 additional cancer deaths related to the accident would appear "among the 600 000 persons receiving more significant exposures (liquidators working in 1986–87, evacuees, and residents of the most contaminated areas)". Russia, Ukraine, and Belarus have been burdened with the continuing and substantial decontamination and health care costs of the Chernobyl disaster.

福島第一核電廠事故

主条目：福岛第一核电站事故

Following an earthquake, tsunami, and failure of cooling systems at Fukushima I Nuclear Power Plant and issues concerning other nuclear facilities in Japan on March 11, 2011, a nuclear emergency was declared. This was the first time a nuclear emergency had been declared in Japan, and 140,000 residents within 20 km（12 mi） of the plant were evacuated. Explosions and a fire have resulted in dangerous levels of radiation, sparking a stock market collapse and panic-buying in supermarkets. The UK, France and some other countries advised their nationals to consider leaving Tokyo, in response to fears of spreading nuclear contamination. The accidents have drawn attention to ongoing concerns over Japanese nuclear seismic design standards and caused other governments to re-evaluate their nuclear programs. As of April 2011, water is still being poured into the damaged reactors to cool melting fuel rods. John Price, a former member of the Safety Policy Unit at the UK's National Nuclear Corporation, has said that it "might be 100 years before melting fuel rods can be safely removed from Japan's Fukushima nuclear plant".

三浬島事件

主条目：三哩岛核泄漏事故

President Jimmy Carter leaving Three Mile Island for Middletown, Pennsylvania, April 1, 1979.

当天凌晨4时半，三哩岛核电站95万千瓦压水堆电站二号反应堆主给水泵停转，辅助给水泵按照预设的程序启动，但是由于辅助回路中隔离阀门在此前的例行检修中没有按规定打开，导致辅助回路没有正常启动。二號回路冷却水没有按照程序进入蒸汽发生器，热量在反應堆中心處持續聚集，堆心压力上升。堆心压力的上升导致稳压器减压阀开启，冷却水流出，由于发生机械故障，在堆心压力回复正常值后堆心冷却水继续注入减压水槽，造成减压水槽水满外溢。一號回路冷却水大量排出造成堆心温度上升，待运行人员发现问题所在的时候，堆心燃料的47%已经融毁并发生泄漏，系统发出了放射性物质外漏的警报，但由于警报響起時并未引起运行人员的注意，甚至现时的紀錄報告都指出沒有人注意到警报。直到当天晚上8点，二号堆一二回路均恢复正常运转，但运行人员始终没有察觉堆心的损坏和放射性物质的外漏。

此后，第76任賓州州長迪克·松伯（Dick Thornburgh）出于安全考虑，于3月30日疏散了核电站五英里范围内的学龄前儿童和孕妇，并下令对事故堆芯进行检查。检查中才发现堆心严重损坏，约20吨的二氧化铀堆积在反應爐壓力槽底部，大量放射性物质堆积在核反應堆安全殼內，少部分放射性物质泄漏到周围环境中。

Issues

Nuclear power plants are a complex energy system and opponents of nuclear power have criticized the sophistication and complexity of the technology. Helen Caldicott has said: "... in essence, a nuclear reactor is just a very sophisticated and dangerous way to boil water -- analogous to cutting a pound of butter with a chain saw." The 1979 Three Mile Island accident inspired Charles Perrow's book Normal Accidents, where a nuclear accident occurs, resulting from an unanticipated interaction of multiple failures in a complex system. TMI was an example of a normal accident because it was "unexpected, incomprehensible, uncontrollable and unavoidable".

Perrow concluded that the failure at Three Mile Island was a consequence of the system's immense complexity. Such modern high-risk systems, he realized, were prone to failures however well they were managed. It was inevitable that they would eventually suffer what he termed a 'normal accident'. Therefore, he suggested, we might do better to contemplate a radical redesign, or if that was not possible, to abandon such technology entirely.

The nuclear power industry has improved the safety and performance of reactors, and has proposed new safer (but generally untested) reactor designs but there is no guarantee that the reactors will be designed, built and operated correctly. Mistakes do occur and the designers of reactors at Fukushima in Japan did not anticipate that a tsunami generated by an earthquake would disable the backup systems that were supposed to stabilize the reactor after the earthquake. According to UBS AG, the Fukushima I nuclear accidents have cast doubt on whether even an advanced economy like Japan can master nuclear safety. Catastrophic scenarios involving terrorist attacks are also conceivable. An interdisciplinary team from MIT have estimated that given a three-fold increase in nuclear power from 2005 to 2055, and an unchanged accident frequency, four core damage accidents would be expected in that period

The impact of nuclear accidents has been a topic of debate practically since the first nuclear reactors were constructed. It has also been a key factor in public concern about nuclear facilities. Some technical measures to reduce the risk of accidents or to minimize the amount of radioactivity released to the environment have been adopted. Despite the use of such measures, "there have been many accidents with varying impacts as well near misses and incidents".

Benjamin K. Sovacool has reported that worldwide there have been 99 accidents at nuclear power plants. Fifty-seven accidents have occurred since the Chernobyl disaster, and 57% (56 out of 99) of all nuclear-related accidents have occurred in the USA. Serious nuclear power plant accidents include the Fukushima Daiichi nuclear disaster (2011), Chernobyl disaster (1986), Three Mile Island accident (1979), and the SL-1 accident (1961). Nuclear-powered submarine mishaps include the K-19 reactor accident (1961), the K-27 reactor accident (1968), and the K-431 reactor accident (1985).

Proponents of nuclear power argue that in comparison to any other form of power, nuclear power is the safest form of energy, accounting for all the risks from mining to production to storage, including the risks of spectacular nuclear accidents. Accidents in the nuclear industry have been less damaging than accidents in the hydro industry, and less damaging than the constant, incessant damage from air pollutants from fossil fuels. Coal plants release more radioactivity into the environment than nuclear plants, through the release of thorium and uranium in coal ash. The World Nuclear Association provides a comparison of deaths from accidents in course of different forms of energy production. In their comparison, deaths per TW-yr of electricity produced from 1970 to 1992 are quoted as 885 for hydropower, 342 for coal, 85 for natural gas, and 8 for nuclear. Nuclear power plant accidents rank first in terms of their economic cost, accounting for 41 percent of all property damage attributed to energy accidents.

Health effects on population near nuclear power plants and workers

Fishermen near the now-dismantled Trojan Nuclear Power Plant in Oregon. The reactor dome is visible on the left, and the cooling tower on the right.

参见：Environmental impact of nuclear power § Risk of cancer

A major concern in the nuclear debate is what the long-term effects of living near or working in a nuclear power station are. These concerns typically center around the potential for increased risks of cancer. However, studies conducted by non-profit, neutral agencies have found no compelling evidence of correlation between nuclear power and risk of cancer.

There has been considerable research done on the effect of low-level radiation on humans. Debate on the applicability of Linear no-threshold model versus Radiation hormesis and other competing models continues, however, the predicted low rate of cancer with low dose means that large sample sizes are required in order to make meaningful conclusions. A study conducted by the National Academy of Science found that carcinogenic effects of radiation does increase with dose. The largest study on nuclear industry workers in history involved nearly a half-million individuals and concluded that a 1–2% of cancer deaths were likely due to occupational dose. This was on the high range of what theory predicted by LNT, but was "statistically compatible".

The Nuclear Regulatory Commission (NRC) has a factsheet that outlines 6 different studies. In 1990 the United States Congress requested the National Cancer Institute to conduct a study of cancer mortality rates around nuclear plants and other facilities covering 1950 to 1984 focusing on the change after operation started of the respective facilities. They concluded in no link. In 2000 the University of Pittsburgh found no link to heightened cancer deaths in people living within 5 miles of plant at the time of the Three Mile Island accident. The same year, the Illinois Public Health Department found no statistical abnormality of childhood cancers in counties with nuclear plants. In 2001 the Connecticut Academy of Science and Engineering confirmed that radiation emissions were negligibly low at the Connecticut Yankee Nuclear Power Plant. Also that year, the American Cancer Society investigated cancer clusters around nuclear plants and concluded no link to radiation noting that cancer clusters occur regularly due to unrelated reasons. Again in 2001, the Florida Bureau of Environmental Epidemiology reviewed claims of increased cancer rates in counties with nuclear plants, however, using the same data as the claimants, they observed no abnormalities.

Scientists learned about exposure to high level radiation from studies of the effects of bombing populations at Hiroshima and Nagasaki. However, it is difficult to trace the relationship of low level radiation exposure to resulting cancers and mutations. This is because the latency period between exposure and effect can be 25 years or more for cancer and a generation or more for genetic damage. Since nuclear generating plants have a brief history, it is early to judge the effects.

Most human exposure to radiation comes from natural background radiation. Natural sources of radiation amount to an average annual radiation dose of 295 mrem. The average person receives about 53 mrem from medical procedures and 10 mrem from consumer products. According to the National Safety Council, people living within 50 miles of a nuclear power plant receive an additional 0.01 mrem per year. Living within 50 miles of a coal plant adds 0.03 mrem per year.

Current guidelines established by the NRC, require extensive emergency planning, between nuclear power plants, Federal Emergency Management Agency (FEMA), and the local governments. Plans call for different zones, defined by distance from the plant and prevailing weather conditions and protective actions. In the reference cited, the plans detail different categories of emergencies and the protective actions including possible evacuation.

A German study on childhood cancer in the vicinity of nuclear power plants, the KiKK study was published in December 2007. According to Ian Fairlie, it "resulted in a public outcry and media debate in Germany which has received little attention elsewhere". It has been established "partly as a result of an earlier study by Körblein and Hoffmann which had found statistically significant increases in solid cancers (54%), and in leukemia (76%) in children aged less than 5 within 5 km of 15 German nuclear power plant sites. It reported a 2.2-fold increase in leukemias and a 1.6-fold increase in solid (mainly embryonal) cancers among children living within 5 km of all German nuclear power stations." In 2011 a new study of the KiKK data was incorporated into an assessment by the Committee on Medical Aspects of Radiation in the Environment (COMARE) of the incidence of childhood leukemia around British nuclear power plants. It found that the control sample of population used for comparison in the German study may have been incorrectly selected and other possible contributory factors, such as socio-economic ranking, were not taken into consideration. The committee concluded that there is no significant evidence of an association between risk of childhood leukemia (in under 5 year olds) and living in proximity to a nuclear power plant.

Safety culture in host nations

Some developing countries which plan to go nuclear have very poor industrial safety records and problems with political corruption. Inside China, and outside the country, the speed of the nuclear construction program has raised safety concerns. Prof He Zuoxiu, who was involved with China's atomic bomb program, has said that plans to expand production of nuclear energy twentyfold by 2030 could be disastrous, as China was seriously underprepared on the safety front. China's fast-expanding nuclear sector is opting for cheap technology that "will be 100 years old by the time dozens of its reactors reach the end of their lifespans", according to diplomatic cables from the US embassy in Beijing. The rush to build new nuclear power plants may "create problems for effective management, operation and regulatory oversight" with the biggest potential bottleneck being human resources – "coming up with enough trained personnel to build and operate all of these new plants, as well as regulate the industry". The challenge for the government and nuclear companies is to "keep an eye on a growing army of contractors and subcontractors who may be tempted to cut corners". China is advised to maintain nuclear safeguards in a business culture where quality and safety are sometimes sacrificed in favor of cost-cutting, profits, and corruption. China has asked for international assistance in training more nuclear power plant inspectors.

核擴散與恐怖主義

According to Mark Z. Jacobson, the growth of nuclear power has "historically increased the ability of nations to obtain or enrich uranium for nuclear weapons, and a large-scale worldwide increase in nuclear energy facilities would exacerbate this problem, putting the world at greater risk of a nuclear war or terrorism catastrophe". The historic link between energy facilities and weapons is evidenced by the secret development or attempted development of weapons capabilities in nuclear power facilities in Pakistan, India, Iraq (prior to 1981), Iran, and to some extent in North Korea.

Four AP1000 reactors, which were designed by the American Westinghouse Electric Company are currently, as of 2011, being built in China and a further two AP1000 reactors are to be built in the USA. Hyperion Power Generation, which is designing modular reactor assemblies that are proliferation resistant, is a privately owned US corporation, as is Terrapower which has the financial backing of Bill Gates.

Vulnerability of plants to attack

Nuclear reactors become preferred targets during military conflict and, over the past three decades, have been repeatedly attacked during military air strikes, occupations, invasions and campaigns:

• In September 1980, Iran bombed the Al Tuwaitha nuclear complex in Iraq.
• In June 1981, an Israeli air strike completely destroyed Iraq’s Osirak nuclear research facility.
• Between 1984 and 1987, Iraq bombed Iran’s Bushehr nuclear plant six times.
• In Iraq in 1991, the U.S. bombed three nuclear reactors and an enrichment pilot facility.
• In 1991, Iraq launched Scud missiles at Israel’s Dimona nuclear power plant.
• In September 2003, Israel bombed a Syrian reactor under construction.

According to a 2004 report by the U.S. Congressional Budget Office, "The human, environmental, and economic costs from a successful attack on a nuclear power plant that results in the release of substantial quantities of radioactive material to the environment could be great." Such an attack would, however, be difficult to mount. U.S. reactors are surrounded by a double row of electronically monitored tall fences, and patrolled by a sizable force of armed guards. Modern nuclear reactor containment buildings are designed to be impervious to a September 11-style attack. If terrorists were able to gain access to a nuclear reactor, they could do little more than vandalize the equipment. The National Reconnaissance Office's "Design Basis Threat" criteria for nuclear plant security is classified; what size attacking force the plants are able to protect against is unclear. Scramming a plant takes less than 5 seconds, while unimpeded restart takes several hours, severely hampering any efforts to release radioactivity into the atmosphere. Attacks on chemical industry or petroleum industry plants, which are much more vulnerable to terrorism, would result in similarly dangerous outcomes, sometimes more lethal than an attack on the nuclear power industry.

Use of waste byproduct as a weapon

An additional concern with nuclear power plants is that if the by-products of nuclear fission (the nuclear waste generated by the plant) were to be left unprotected it could be stolen and used as a radiological weapon, colloquially known as a "dirty bomb". There were incidents in post-Soviet Russia of nuclear plant workers attempting to sell nuclear materials for this purpose (for example, there was such an incident in Russia in 1999 where plant workers attempted to sell 5 grams of radioactive material on the open market, and an incident in 1993 where Russian workers were caught attempting to sell 4.5 kilograms of enriched uranium.), and there are additional concerns that the transportation of nuclear waste along roadways or railways opens it up for potential theft. The United Nations has since called upon world leaders to improve security in order to prevent radioactive material falling into the hands of terrorists, and such fears have been used as justifications for centralized, permanent, and secure waste repositories and increased security along transportation routes.

However, scientists agree that the spent fissile fuel is not radioactive enough to create any sort of effective nuclear weapon, in a traditional sense where the radioactive material is the means of explosion.

民意

A poll in the European Union for Feb-Mar 2005 showed 37% in favour of nuclear energy and 55% opposed, leaving 8% undecided. The same agency ran another poll in Oct-Nov 2006 that showed 14% favoured building new nuclear plants, 34% favoured maintaining the same number, and 39% favoured reducing the number of operating plants, leaving 13% undecided. This poll showed that respondents with a lower level of education and that women were less likely to approve.

The two fuel sources that attracted the highest levels of support in the 2007 MIT Energy Survey are solar power and wind power. Outright majorities would choose to "increase a lot" use of these two fuels, and better than three out of four Americans would like to increase these fuels in the U. S. energy portfolio. Fourteen per cent of respondents would like to see nuclear power "increase a lot".

What had been growing acceptance of nuclear power in the United States was eroded sharply following the 2011 Japanese nuclear accidents, with support for building nuclear power plants in the U.S. dropping slightly lower than it was immediately after the Three Mile Island accident in 1979, according to a CBS News poll. Only 43 percent of those polled after the Fukushima nuclear emergency said they would approve building new power plants in the United States.

A 2011 poll suggests that skepticism over nuclear power is growing in Sweden following Japan's nuclear crisis. 36 percent of respondents want to phase-out nuclear power, up from 15 percent in a similar survey two years ago.

In 2011, London-based bank HSBC said: "With Three Mile Island and Fukushima as a backdrop, the US public may find it difficult to support major nuclear new build and we expect that no new plant extensions will be granted either. Thus we expect the clean energy standard under discussion in US legislative chambers will see a far greater emphasis on gas and renewables plus efficiency".

In 2011, Deutsche Bank analysts concluded that "the global impact of the Fukushima accident is a fundamental shift in public perception with regard to how a nation prioritizes and values its populations health, safety, security, and natural environment when determining its current and future energy pathways". As a consequence, "renewable energy will be a clear long-term winner in most energy systems, a conclusion supported by many voter surveys conducted over the past few weeks. At the same time, we consider natural gas to be, at the very least, an important transition fuel, especially in those regions where it is considered secure".

In June 2011, both Ipsos Mori and the Japanese Asahi Shimbun newspaper found drops in support for nuclear power technology in most countries, with support continuing in a number including the US. The Ipsos Mori poll found that nuclear had the lowest support of any established technology for generating electricity, with 38%. Coal was at 48% support while solar energy, wind power and hydro all found favour with more than 90% of those surveyed.

There is little support across the world for building new nuclear reactors, a 2011 poll for the BBC indicates. The global research agency GlobeScan, commissioned by BBC News, polled 23,231 people in 23 countries from July to September 2011, several months after the Fukushima nuclear disaster. In countries with existing nuclear programmes, people are significantly more opposed than they were in 2005, with only the UK and US bucking the trend. Most believe that boosting energy efficiency and renewable energy can meet their needs.

Just 22% agreed that "nuclear power is relatively safe and an important source of electricity, and we should build more nuclear power plants". In contrast, 71% thought their country "could almost entirely replace coal and nuclear energy within 20 years by becoming highly energy-efficient and focusing on generating energy from the Sun and wind". Globally, 39% want to continue using existing reactors without building new ones, while 30% would like to shut everything down now.

核能工業的未來

As of May 15, 2011, a total of 438 nuclear reactors were operating in 30 countries, six fewer than the historical maximum of 444 in 2002. Since 2002, utilities have started up 26 units and disconnected 32 including six units at the Fukushima Daiichi nuclear power plant in Japan. The current world reactor fleet has a total nominal capacity of about 372 gigawatts (or thousand megawatts). Despite six fewer units operating in 2011 than in 2002, the capacity is still about 9 gigawatts higher. The numbers of new operative reactors, final shutdowns and new initiated constructions according to International Atomic Energy Agency (IAEA) in recent years are as follows:

Year	New connections		Shutdowns		Net change			Construction initiation
	# of reactors	GW	# of reactors	GW	# of reactors	GW		# of reactors	GW
2004	5	4.8	5	1.4	0	+3.4		2	1.3
2005	4	3.8	2	0.9	+2	+2.9		3	2.9
2006	2	1.5	8	2.2	−6	−0.7		4	3.3
2007	3	1.9	0	––	+3	+1.9		8	6.5
2008	0	––	1	0.4	−1	−0.4		10	10.5
2009	2	1.0	3	2.5	−1	−1.4		12	13.1
2010	5	3.8	1	0.1	+4	+3.6		16	15.8
2011	7	4.0	13	11.4	−6	−7.4		2	0.9

Stephanie Cooke has argued that the cost of building new reactors is extremely high, as are the risks involved. Most utilities have said that they won't build new plants without government loan guarantees. There are also bottlenecks at factories that produce reactor pressure vessels and other equipment, and there is a shortage of qualified personnel to build and operate the reactors, although the recent acceleration in nuclear power plant construction is drawing a substantial expansion of the heavy engineering capability.

Following the Fukushima Daiichi nuclear disaster, the International Energy Agency halved its estimate of additional nuclear generating capacity to be built by 2035. Platts has reported that "the crisis at Japan's Fukushima nuclear plants has prompted leading energy-consuming countries to review the safety of their existing reactors and cast doubt on the speed and scale of planned expansions around the world". In 2011, The Economist reported that nuclear power "looks dangerous, unpopular, expensive and risky", and that "it is replaceable with relative ease and could be forgone with no huge structural shifts in the way the world works".

In September 2011, German engineering giant Siemens announced it will withdraw entirely from the nuclear industry, as a response to the Fukushima nuclear disaster in Japan. The company is to boost its work in the renewable energy sector. Commenting on the German government's policy to close nuclear plants, Werner Sinn, president of the Ifo Institute for Economic Research at the University of Munich, stated: "It is wrong to shut down the atomic power plants, because this is a cheap source of energy, and wind and solar power are by no means able to provide a replacement. They are much more expensive, and the energy that comes out is of inferior quality. Energy-intensive industries will move out, and the competitiveness of the German manufacturing sector will be reduced or wages will be depressed."

In 2011, Mycle Schneider spoke of a global downward trend in the nuclear power industry:

The international nuclear lobby has pursued a 10-year-long, massive propaganda strategy aimed at convincing decision-makers that atomic technology has a bright future as a low-carbon energy option... however, most of the high-flying nuclear plans never materialized. The historic maximum of reactors operating worldwide was achieved in 2002 with 444 units. In the European Union the historic peak was reached as early as 1988 with 177 reactors, of which only 134 are left. The only new projects underway in Europe are heavily over budget and much delayed.

As Time magazine rightly stated in March, "Nuclear power is expanding only in places where taxpayers and ratepayers can be compelled to foot the bill." China is building 27 -- or more than 40 percent -- of the 65 units officially under construction around the world. Even there, though, nuclear is fading as an energy option. While China has invested the equivalent of about $10 billion per year into nuclear power in recent years, in 2010 it spent twice as much on wind energy alone and some $54.5 billion on all renewables combined.

In contrast, proponents of nuclear power argue that nuclear power has killed by far the fewest number of people per terawatt hour of any type of power generation, and it has a very small impact on the environment with effectively zero emissions of any kind. And this even taking into account the Chernobyl and Fukushima accidents, in which few people were killed directly and few excess cancers will be caused by releases of radioactivity to the environment. Some proponents acknowledge that most people will not accept this sort of statistical argument nor will they believe reassuring statements from industry or government. Indeed, the industry itself has created fear of nuclear power by pointing out that radioactivity can be dangerous. Improved communication by industry might help to overcome current fears regarding nuclear power, but it will be a difficult task to change current perceptions in the general population.

But with regard to the proposition that "Improved communication by industry might help to overcome current fears regarding nuclear power", M.V. Ramana says that the basic problem is that there is "distrust of the social institutions that manage nuclear energy", and a 2001 survey by the European Commission found that "only 10.1 percent of Europeans trusted the nuclear industry". This public distrust is periodically reinforced by safety violations by nuclear companies, or through ineffectiveness or corruption on the part of nuclear regulatory authorities. Once lost, says Ramana, trust is extremely difficult to regain. Faced with public antipathy, the nuclear industry has "tried a variety of strategies to persuade the public to accept nuclear power", including the publication of numerous "fact sheets" that discuss issues of public concern. Ramana says that none of these strategies have been very successful.

In March 2012, E.ON UK and RWE npower announced they would be pulling out of developing new nuclear power plants in the UK, placing the future of nuclear power in the UK in doubt. More recently, Centura (who own British Gas) pulled out of the race on 04 February 2013 by letting go its 20% option on four new nuclear plants. Cumbria county council (a local authority) turned down an application for a final waste repository on 30 January 2013 — there is currently no alternative site on offer.

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