NUCLEAR ELECTRICITY
(Seventh edition, 2003)

CHAPTER 6

EXTERNAL COSTS - ENVIRONMENT, HEALTH AND SAFETY ISSUES

External costs of electricity generation are defined as those costs actually incurred in relation to health and the environment and quantifiable, but not built into the cost of the electricity to the consumer and therefore which are borne by society at large. They include particularly the effects of air pollution on human health, crop yields and buildings, as well as occupational disease and accidents. Though they are even harder to quantify and evaluate than the others, they include effects on ecosystems and the impact of global warming.

6.1 Environmental effects

The production of electricity from any form of primary energy has some environmental effect. A balanced assessment of nuclear power requires comparison of its environmental effects with those of the principal alternative, coal-fired electricity generation.

At a uranium mine ordinary operating procedures normally ensure that there is no significant water or air pollution. The environmental effect of coal mining today is also small except that larger tracts may require subsequent rehabilitation, and in certain areas acid mine drainage can be a problem. The effects of uranium mining are discussed more fully in Section 4.1.

Small amounts of radioactivity are released to the atmosphere from both coal-fired and nuclear power stations. In the case of coal combustion small quantities of uranium, radium and thorium present in the coal cause the fly ash to be radioactive, the level varying considerably. Nuclear power stations and reprocessing plants release small quantities of radioactive gases (e.g, krypton-85 and xenon-133) and iodine-131 which may also be detectable in the environment with sophisticated monitoring or analytical equipment. Steps are being taken to reduce further emissions of both fly ash from coal-fired power stations and radionuclides from nuclear power stations and other plants. At present neither constitutes a significant environmental problem.

As outlined in Sections 5.3-5.5, solid high-level waste from nuclear power stations is stored for 40-50 years while the radioactivity decays to less than one percent of its original level. Then it will be finally disposed of well away from the biosphere. Intermediate-level waste is placed in underground repositories. Low-level waste is generally buried more conventionally. Radioactive fly ash from coal-fired power stations has in the past had a much greater environmental impact largely because it was not perceived as a problem and appropriate action was not taken. Where today it is buried in dams, seepage and run-off needs to be controlled.

Waste heat produced due to the intrinsic inefficiency of energy conversion, and hence as a by-product of power generation, is much the same whether coal or uranium is the primary fuel. The thermal efficiency of coal-fired power stations ranges from about 20 percent to a possible 40 percent, with newer ones typically giving better than 32 percent. That of nuclear stations mostly ranges from 29-38 percent with the common light water reactor today giving about 34 percent. There is no reason for preferring one fuel over the other on account of waste heat. This is the case whether power station cooling is by water from a stream or estuary, or using atmospheric cooling towers. In any case this heat need not always be "waste". In colder climates district heating and agricultural uses are increasingly found. These decrease the extent to which local fogs result from the release of heat to the environment.

The main environmental matter relevant to power generation is the production of carbon dioxide (CO₂) and sulfur dioxide (SO2) as a result of coal-fired electricity generation. When coal of say 2.5 percent sulphur is used to produce the electricity for one person in an industrialised country for one year, then about 9 tonnes of CO₂ and 120 kg of SO₂ are produced (see Figure 6 in chapter 2). CO₂ is also produced by the combustion of other fossil fuels such as oil and gas.

Sulfur dioxidein large quantities released to the atmosphere can cause (sulfuric) "acid rains" in areas downwind. In the northern hemisphere many millions of tonnes of SO₂ are released annually from electricity generation, though such pollution has been dramatically reduced. The acid rain (rainwater having a pH of 4 and lower) in north-eastern USA and Scandinavia causes ecological changes and economic loss. In the UK and the USA electric power utilities at first sought to minimise this by increasing their use of oil with less sulfur, or natural gas. However, this strategy raises ethical issues due to the value of oil for transport and gas for reticulation to individual homes and industries.

It is possible to remove a lot of the SO₂ from coal stack gases, but the cost is considerable. Power utilities however have spent many billions of dollars on this. On the other hand, between 1980 and 1986 SO₂ emissions in France were halved simply by replacing fossil fuel power stations with nuclear. At the same time electricity production increased 40 percent and France became a significant exporter of electricity.

Oxides of nitrogen (NOx) from fossil fuel power stations are also an environmental problem. If high levels of hydrocarbons are present in the air, nitrogen oxides react with these to form photochemical smog. Also, oxides of nitrogen have an adverse effect on the earth's ozone layer, thereby increasing the amount of ultra-violet light transmitted to the earth's surface.

6.2 The Greenhouse Effect

This term refers to the effect of certain trace gases in the earth's atmosphere so that long-wave radiation such as heat from the earth's surface is trapped. A build-up of "greenhouse gases", notably CO₂, appears to be causing a warming of the climate in many parts of the world, which if continued will cause changes in weather patterns and other profound changes. Much of the greenhouse effect is due to carbon dioxide.*

*CO₂ constitutes only 0.035% (350 ppm) of the atmosphere. An increase from 280 to 350 ppm appears to have already occurred since the beginning of the Industrial Revolution.

While our understanding of relevant processes is advancing, we do not know how much carbon dioxide the environment can absorb, nor how long-term global CO₂ balance is maintained. However, scientists are increasingly concerned about the slow worldwide build-up of CO₂ levels in the atmosphere. This is occurring as the world's carbon-based fossil fuels are being burned and rapidly converted to atmospheric CO₂ e.g. in motor vehicles, domestic and industrial furnaces, and electric power generation. Progressive clearing of the world's forests also contributes to the greenhouse effect by diminishing the removal of atmospheric CO₂ by photosynthesis.

As early as 1977 a USA National Academy of Sciences report concluded that "the primary limiting factor on energy production from fossil fuels over the next few centuries may turn out to be the climatic effects of the release of carbon dioxide". Today this is conventional wisdom. The global climatic effect of increasing CO₂ levels is now a very significant factor in the comparison of coal and nuclear power for producing electricity (see Figure 17).

Worldwide emissions of CO₂ from burning fossil fuels total about 25 billion tonnes per year. About 38% of this is from coal and about 43% from oil. Every 1000 MWe power station running on black coal means CO₂ emissions of about 7 million tonnes per year. If brown coal is used, the amount is much greater. If uranium is used in a nuclear power reactor, these emissions do not occur.

Figure 17

Every 22 tonnes of uranium (26 t U₃O₈) used* saves about one million tonnes of CO₂ relative to coal.

* In a light-water reactor.

There is now widespread agreement that we need resource strategies which will minimise CO₂ build-up. In respect to base-load electricity generation, increased use of uranium as a fuel is the most obvious such strategy, utilising proven technology on the scale required. See also Figure 17. Scope for energy conservation is unlikely to be as great in the next decade as since the mid 1970s, because most of the easy and cost-effective steps have already been taken.

6.3 Health effects and radiation

Here the emphasis is on comparing nuclear power with coal-fired power plants for electricity. Both occupational and environmental health effects are considered, along with risks.

Traditionally occupational health risks have been measured in terms of immediate accident fatality rates. However, today, and particularly in relation to nuclear power, there is an increased emphasis on less obvious or delayed effects of exposure to cancer-inducing substances and radiation.

Many occupational accident statistics have been generated over the last 40 years of nuclear reactor operations in USA and UK. These can be compared with those from coal-fired electricity generation. All show that nuclear is distinctly the safer means of electric power generation in this respect. Two simple sets of figures are quoted in Tables 12 & 12A. A major reason for coal showing up unfavourably is the huge amount of it which must be mined and transported to supply even a single large power station. Mining and multiple handling of so much material of any kind involves hazards, and these are reflected in the statistics.

TABLE 12

Comparison of accident statistics in primary energy production.
(Electricity generation accounts for about 40% of total primary energy).

Fuel	Immediate fatalities 1970-92	Who?	Deaths per TWy* electricity
Coal	6400	workers	342
Natural gas	1200	workers & public	85
Hydro	4000	public	883
Nuclear	31	workers	8

*Basis: per million MWe operating for one year (ie about 3 times world nuclear power capacity), not including plant construction, based on historic data - which is unlikely to represent current safety levels in any of the industries concerned. The data in this column was published in 2001 but is consistent with that from 1996-7, where it is pointed out that the coal total would be about ten times greater if accidents with less than 5 fatalities were included.

Source: Ball, Roberts & Simpson, Research Report #20, Centre for Environmental & Risk Management, University of East Anglia, 1994; Hirschberg et al, Paul Scherrer Institut, 1996; in: IAEA, Sustainable Development and Nuclear Power, 1997; Severe Accidents in the Energy Sector, Paul Scherrer Institut; 2001.

TABLE 12A
The Hazards of Using Energy:

LPG and oil accidents with less than 300 fatalities, and coal mine accidents with less than 100 fatalities are generally not shown unless recent.

Deaths per million tonnes of coal mined range from 0.1 per year in Australia and USA to 119 in Turkey. China's total death toll from coal mining averages well over 1000 per year (official figures give 5300 in 2000 and 5670 in 2001); Ukraine's is over two hundred per year (eg. 1999: 274, 1998: 360, 1995: 339, 1992: 459).

In Australia 281 coal miners have been killed in 18 major disasters since 1902, and there have been 112 deaths in NSW mines since 1979, though the Australian coal mining industry is considered the safest in the world.

Sources: contemporary media reports, Paul Scherrer Inst, 1998 report: Severe Accidents in the Energy Sector.

Health risks in uranium mining are largely discussed in Section 4.1. Past exposure of miners to radon gas, with a consequent higher incidence of lung cancer, is historically the most noteworthy aspect of this. However, exposure to high levels of radon has not been a feature of uranium (or other) mines for over thirty years. Nevertheless, the presence of some radon around a uranium mining operation and some dust bearing radioactive decay products must be recognised and compared with the hazards of inhaled coal dust in a coal mine. In both cases, using the best current practice, the health hazards to miners are very small and certainly less than the risks of industrial accidents.

In the nuclear fuel cycle, radiation hazards to workers are low, and industrial accidents are few. Certainly nuclear power generation is not completely free of hazards in the occupational sense, but it does appear to be far safer than other forms of energy conversion. Table 12 covers more than 20 years. Also, since cancer is a common disease in older people there have been, and will continue to be, cancer cases among radiation workers. It does not mean that they are radiation-induced. The occurrence of cancer is not uniform across the world population, and because of local differences it is not easy to see whether or not there is any association between low occupational radiation doses and possible excess cancers. However this question has been studied closely in a number of areas and work is continuing. So far no conclusive evidence has emerged to indicate that cancers are more frequent in radiation workers than in other people of similar ages in western countries, where cancer accounts for a quarter of all deaths. At the low levels of exposure and dose rates involved in the nuclear industry, the effects are probabilistic rather than measurable, as described below.

Environmental (non occupational) health effects are qualitatively similar to those on workers in the industry: those from ionising radiation being rather better understood than those from air pollution, for example. Popular concern about ionising radiation has been promoted by the testing of nuclear weapons. This has mirrored the strong awareness of those in the nuclear power industry concerning radiation hazards. Fortunately radioactivity is readily measurable and its effects fairly well understood compared with those of other hazards with delayed effects, including virtually all chemical cancer-inducing substances. Radiation is a weak carcinogen.

The contrast between air quality effects from coal burning for electricity and increased radiation from nuclear power is very marked: a person living next to a nuclear power plant receives less radiation from it than from a few hours flying each year (see Table 13). On the other hand, anyone downwind of a coal-fired power plant can expect it to have an effect on the air quality, possibly even to the extent of affecting health. In some areas coal contains enough radium and thorium to cause coal-fired power stations to release far more radioactivity to the environment than a nuclear power station, though today this is mostly retained in fly ash.

Table 13 shows some typical levels and sources of radiation exposure. The contribution from the ground and buildings varies from place to place. Across Canada doses from the ground range from about 0.5 to 1.1 millisieverts per year (mSv/yr). Around Sydney they vary from 0.16 to 0.9 mSv/yr, around Armidale, NSW, doses of 2.5 mSv/yr are common, and around Perth, Western Australia, levels range up to 3 mSv/yr. Citizens of Cornwall, UK, receive an average of about 7mSv/yr. Hundreds of thousands of people in India, Brazil and Sudan receive up to 40 mSv/yr and some populations in Iran receive many times more, all without apparent ill-effects. The cosmic radiation dose varies with altitude and latitude. Aircrew can receive up to about 5 mSv/yr from their hours in the air, frequent flyers can score a similar increment. In contrast, UK citizens receive about 0.0003 mSv/yr from nuclear power generation. Appendix 1 gives further background to the topic of radiation and its measurement.

TABLE 13
Ionising radiation

The earth is radioactive, though gradually becoming less so as long-lived isotopes decay. Radioactive decay results in the release of ionising radiation. As well as the earth's radioactivity we are naturally subject to cosmic radiation from space. In addition to both these, we collect some radiation doses from artificial sources such as X-rays. We may also collect an increased cosmic radiation dose due to participating in high altitude activities such as flying or skiing. The average adult contains about 13 mg of radioactive potassium-40 in body tissue - we therefore even irradiate one another at close quarters!

The relative importance of these various sources is indicated in the table below. Types of radiation and units for measuring it are outlined in Appendix 1.

	Typical	Range
	µSv/yr	µSv/yr
Natural:
Terrestrial + house: radon	200	200-100,000
Terrestrial + house: gamma	600	100-1000
Cosmic (at sea level)	300
+20 for every 100m elevation	......	0-500
Food, drink & body tissue	400	100-1000
Total	1500 (plus altitude adjustment)
Artificial:
From nuclear weapons tests	3
Medical (X-ray, CT, etc average)	370	up to 75,000
from nuclear energy	0.3
From coal burning	0.1
From household appliances	0.4
Total	375
Behavioural:
Skiing holiday	8 per week
Air travel in jet airliner	1.5 - 5 per hour	up to 5000/yr

The International Commission for Radiological Protection recommends, in addition to background, the following exposure limits:
* for general public, 1,000 (ie 1 mSv/yr)
* for nuclear worker 20,000 (ie 20 mSv/yr) averaged over 5 consecutive years

Sources: Australian Radiation Protection & Nuclear Safety Agency, National Radiation Protection Board (UK), Australian Nuclear Science and Technology Organisation, various

In practice, radiation protection is based on the understanding that small increases over natural levels of exposure are not likely to be harmful but should be kept to a minimum. To put this into practice the International Commission for Radiological Protection (ICRP) has established recommended standards of protection based on three basic principles:

… Justification. No practice involving exposure to radiation should be adopted unless it produces a net benefit to those exposed or to society generally.

… Optimisation. Radiation doses and risks should be kept as low as reasonably achievable (ALARA), economic and social factors being taken into account.

… Limitation. The exposure of individuals should be subject to dose or risk limits above which the radiation risk would be deemed unacceptable.

These principles apply to the potential for accidental exposures as well as predictable normal exposures.

Underlying these is the application of the "linear hypothesis" based on the idea that any level of radiation dose, no matter how low, involves the possibility of risk to human health. This assumption enables "risk factors" derived from studies of high radiation dose to populations (eg from Japanese bomb survivors) to be used in determining the risk to an individual from low doses*. However the weight of scientific evidence does not indicate any cancer risk or immediate effects at doses below 50 millisievert (mSv) in a short time or about 100 mSv per year. At lower doses and dose rates (up to at least 10 mSv/yr) the evidence suggests that beneficial effects are at least as likely as harmful ones.

*ICRP Publication 60

Based on the three conservative principles, ICRP recommends that the additional dose above natural background and excluding medical exposure should be limited to prescribed levels. These are: one millisievert per year for members of the public, and 20 mSv per year averaged over 5 years for radiation workers who are required to work under closely-monitored conditions (see Table 13).

The actual level of individual risk at the ICRP recommended limit for general public exposure is very small (it is calculated to result in about 1 fatal cancer per year in a population of 20,000 people) and impossible to confirm directly. In the Chernobyl accident (see 6.5), a large number of people were subject to significantly increased radiation exposure, the actual doses being approximately known. In due course this tragedy may result in a better understanding of the effects, if any, of exposure to various levels of radiation. At present most of our knowledge about the effect of radiation on people is derived from the survivors of the Hiroshima and Nagasaki bombings in 1945, where the doses received were difficult to estimate. Certainly there was a clear increase in certain types of leukaemia and lymphoma and of solid cancers as a class among the survivors.

The body has defence mechanisms against damage induced by radiation as well as by chemical carcinogens. These can be stimulated by low levels of exposure, or overwhelmed by very high levels*.

* Tens of thousands of people in each technically-advanced country work in medical and industrial environments where they may be exposed to radiation above background levels. Accordingly they wear monitoring 'badges' while at work, and their exposure is carefully monitored. The health records of these occupationally exposed groups often show that they have lower rates of mortality from cancer and other causes than the general public and, in some cases, significantly lower rates than other workers who do similar work without being exposed to radiation.

Plutonium is a particular concern. It is separated from spent fuel by reprocessing, as discussed in Section 5.2. Plutonium has been called the most toxic element known to man and therefore represented as a hazard that we should do without. However it is pertinent to compare its toxicity with that of other materials with which we live. If swallowed, plutonium is much less toxic than cyanide or lead arsenate and about twice as toxic as the concentrate of caffeine from coffee. Its main danger comes if inhaled as a fine dust and absorbed through the lungs. This would increase the likelihood of cancer 15 or more years afterwards, and there has been one documented fatality from plutonium-induced cancer. However, as a counterpoint to the folkore about plutonium is the fact that about seven tonnes of it were dispersed in the upper atmosphere by nuclear weapons testing over the 30 years following World War II without discernible ill effects.

The health effects of exposure both to radiation and to chemical cancer-inducing agents or toxins must be considered in relation to time. We should be concerned not only about the effects on people presently living, but also about the cumulative effects of actions today over many generations. Some radioactive materials which reach the environment decay to safe levels within days, weeks or a few years, others continue their effect for a long time, as do some chemical cancer-inducing agents and toxins. Certainly this is true of the chemical toxicity of heavy metals such as mercury, cadmium and lead, these of course being a natural part of the human environment anyway, like radiation. The essential task for those in government and industry is to prevent excessive amounts of such toxins harming people, now or in the future. Standards are set in the light of research on environmental pathways by which people might ultimately be affected.

6.4 Genetic effects

About sixty years ago it was discovered that ionising radiation such as that which continually forms part of our environment could induce genetic mutations in fruit flies. Intensive study since then has shown that radiation can similarly induce mutations in plants and test animals. However evidence of genetic damage to humans from radiation, even as a result of the large doses received by atomic bomb survivors in Japan, has not shown any such effects..

In a plant or animal cell the material (DNA) which carries genetic information necessary to cell development, maintenance and division is the critical target for radiation. Much of the damage to DNA is repairable, but in a small proportion of cells the DNA is permanently altered. This may result in death of the cell or development of a cancer, or in the case of cells forming gonad tissue, alterations which continue as genetic changes in subsequent generations. Most such mutational changes are deleterious, very few can be expected to result in improvements.

The levels of radiation allowed for members of the public and for workers in the nuclear industry are such that any increase in genetic effects due to nuclear power will be imperceptible and almost certainly non-existent. Radiation exposure levels are set so as to prevent tissue damage and minimise the risk of cancer. Experimental evidence indicates that these are more likely than genetic damage. Some 75 000 children born of parents who survived high radiation doses at Hiroshima and Nagasaki in 1945 have been the subject of intensive examination. This study confirms that no increase in genetic abnormalities in human populations is likely as a result of even quite high doses of radiation.

Life on earth commenced and developed when the environment was probably subject to several times as much radioactivity as it is now, so radiation is not a new phenomenon. If we ensure that there is no dramatic increase in people's general radiation exposure, it is most unlikely that genetic damage due to radiation will ever become significant.

6.5 Reactor safety

There have been sophisticated statistical studies on reactor safety. However, for most people actual performance is more convincing than probability statistics.

The situation to date is that in over 10,500 reactor-years of civil operation there has been only one accident to a commercial reactor which was not substantially contained within the design and structure of the reactor. And only this one, exemplifying the "worst case" disaster scenario, has resulted in loss of life. This is remarkable for the first five decades of a complex new technology which is being used in 31 countries, some reactors now operating having been built over forty years ago. However, this does not give us grounds to rule out the possibility of another major disaster, even where normal engineering standards have been applied.

Most disaster scenarios involve primarily a loss of cooling. This may lead to the fuel in the reactor core overheating and releasing fission products. Hence the provision of emergency core cooling systems on standby. In case these should fail, a further protective barrier comes into play: the reactor core is normally enclosed in structures designed to prevent radioactive releases to the environment. As became evident in 1986, not all Soviet-designed reactors have the same "defence-in-depth" protection. About one third of the capital cost of reactors is normally due to engineering designed to enhance the safety of people - both operators and neighbours, if and when things go wrong. Table 14 shows the international scale for reporting nuclear accidents or incidents.

The 1979 accident at Three Mile Island in USA drew attention to the complex engineering involved in minimising the possibility of fuel meltdown and containing other effects of major malfunctions. The total radioactivity release from this accident was small, and the maximum dose to individuals living near the power plant was well below internationally-accepted limits, even though the reactor was written off. Containment works. Nevertheless, this accident had a pronounced psychological effect, was a severe blow to the US nuclear industry and had an adverse effect on the growth of nuclear capacity in USA and beyond.

The 1986 accident at Chernobyl in Ukraine was very serious and cost the lives of 31 staff and firefighters, 28 of them from acute radiation exposure. There have also been 800 cases of thyroid cancer in children, most of which were curable, though about ten have been fatal. No increase in leukaemia and other cancers had shown up in the first decade, but the World Health Organisation (WHO) expects some increase in cancers over the next decade, and the death toll from delayed health effects may well climb beyond the ten or so thyroid cancer victims. About 130,000 people received significant radiation doses (i.e. above ICRP limits), and are being closely monitored by WHO. Radioactive pollution drifted across a wide area of Europe and Scandinavia, causing disruption to agricultural production and some exposure (small doses) to a large population.*

* See: Chernobyl Ten Years On, OECD NEA 1996.

The accident drew public attention to the lack of an adequate containment structure such as is standard on Western reactors. In addition, the RBMK design was such that coolant failure leads to strong increase in power output from the fission process. Under abnormal conditions all reactor types may experience power increases, which are controlled by the reactor shutdown system. Light water reactors, in which the coolant serves as moderator, automatically reduce power when the coolant/moderator is lost, and can then be shut down using the control rods. In CANDU reactors, with separate moderator and coolant, the same level of safety is assured by having two systems that are functionally and physically independent of each other. One is a shutdown system where solid shutoff rods drop from the top and in the other a liquid "poison" is injected into the moderator water. Both have the effect of stopping the chain reaction by absorbing the neutrons.

The Chernobyl accident resulted from a combination of design deficiencies, the violation of operating procedures and the absence of a safety culture. With assistance from the West, significant safety improvements have been made to the 15 RBMK reactors in operation in Russia, Ukraine and Lithuania and the one under construction in Russia. Russian reactor design has since been standardised on PWR types, with containment structures.

Soon after the accident the destroyed Chernobyl 4 reactor was enclosed in a large concrete shed. The other three units on the site initially resumed operation, though they have since shut down, the last at the end of 2000.

An OECD expert report on it concluded that "the Chernobyl accident has not brought to light any new, previously unknown phenomena or safety issues that are not resolved or otherwise covered by current reactor safety programmes for commercial power reactors in OECD Member countries."

Table 14.

There have been a number of accidents in experimental reactors and in one military plutonium-producing pile, but none of these has resulted in loss of life outside the actual plant, or long-term environmental contamination. The following table (Table 15) of serious reactor accidents includes those in which fatalities have occurred, together with the most serious commercial plant accidents. The list probably corresponds to incidents rating 4 or higher on today's International Nuclear Event Scale (Table 14). It should be emphasised that a commercial-type reactor simply cannot under any circumstances explode like a nuclear bomb.

TABLE 15
Serious reactor accidents
Serious accidents in military, research and commercial reactors. All except Browns Ferry and Vandellos involved damage to or malfunction of the reactor core. At Browns Ferry a fire damaged control cables and resulted in an 18-month shutdown for repairs, at Vandellos a turbine fire made the 17 year old plant uneconomic to repair.

Reactor	Date	Immediate Deaths	Environmental effect	Follow-up action
NRX, Canada (experimental, 40 MWt)	1952	Nil	Nil	Repaired (new core) closed 1992
Windscale-1, UK (military plutonium-producing pile)	1957	Nil	Widespread contamination. Farms affected (c 1.5 x 1015 Bq released)	Entombed (filled with concrete) Being demolished.
SL-1, USA (experimental, military, 3 MWt)	1961	Three operators	Very minor radioactive release	Decommissioned
Fermi-1 USA (experimental breeder, 66 MWe)	1966	Nil	Nil	Repaired, restarted 1972
Lucens, Switzerland (experimental, 7.5 MWe)	1969	Nil	Very minor radioactive release	Decommissioned
Browns Ferry, USA (commercial, 2 x 1080 MWe)	1975	Nil	Nil	Repaired
Three-Mile Island-2, USA (commercial, 880 MWe)	1979	Nil	Minor short-term radiation dose (within ICRP limits) to public, delayed release of 2 x 1014 Bq of Kr-85	Clean-up program complete, in monitored storage stage of decommissioning
Saint Laurent-A2, France (commercial, 450 MWe)	1980	Nil	Minor radiation release (8 x 1010 Bq)	Repaired, (Decomm. 1992)
Chernobyl-4, Ukraine (commercial, 950 MWe)	1986	31 staff and firefighters	Major radiation release across E.Europe and Scandinavia (11 x 1018 Bq)	Entombed
Vandellos-1, Spain (commercial, 480 MWe)	1989	Nil	Nil	Decommissioned

(The well publicised accident at Tokai-mura, Japan, in 1999 was at a fuel preparation plant for experimental reactors, and killed two people from radiation exposure. Many other such criticality accidents have occurred, some fatal, and practically all in military facilities prior to 1980.)

Despite the commercial nuclear power industry's impressive safety record and the thorough engineering of reactor structures and systems which make a catastrophic radioactive release from any Western reactor extremely unlikely, there are those who simply don't want to run any risk of this. This fear must then be weighed against the benefits of nuclear power, in the same way that some people's fear of having aeroplanes crash on top of them must be balanced against the utility of air transport for the rest of the population. Ultimately, balancing risks and benefits is not simply a scientific exercise.

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