放射性核廢料－迷思與現實 Radioactive Wastes - Myths and Realities
以下內容來自於World Nuclear Association：http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Nuclear-Wastes/Radioactive-Wastes---Myths-and-Realities/
- There are a number of pervasive myths regarding both radiation and radioactive wastes.
- Some lead to regulation and actions which are counterproductive to human health and safety.
多年來，媒體報導了許多對於核能發電的觀點與憂慮，其中有來自於大眾以及其他與核能產業，尤其是核廢料，相關團體的看法。由於核廢料的處置議題似乎仍未解決，許多關於核能發電是否應該繼續的問題已經浮現出來。 Over the years, many views and concerns have been expressed in the media, by the public and other interested groups in relation to the nuclear industry and in particular its waste. Questions have been raised about whether nuclear power should continue when the issue of how to deal with its waste has apparently not yet been resolved.
Some views and concerns include:
- 1. 核能產業仍然無法處理「核廢料問題」，因此在解決之前都不應該支持建造任何新核能發電廠。
- 1. The nuclear industry still has no solution to the 'waste problem', so cannot expect support for construction of new plants until this is remedied.
- 2. 核廢料的運送過程會對人類與環境造成無法承受的危害。
- 2. The transportation of this waste poses an unacceptable risk to people and the environment.
- 3. 「鈾」是世界上最危險的物質。
- 3. Plutonium is the most dangerous material in the world.
- 4. 大型貯藏核廢料會造成恐怖攻擊的威脅，並且可能因恐怖攻擊而使得核廢料外漏。
- 4. There is a potential terrorist threat to the large volumes of radioactive wastes currently being stored and the risk that this waste could leak or be dispersed as a result of terrorist action.
- 5. 核廢料經過萬年之後還是有害的，這明顯對於我們的後代是巨大的威脅。
- 5. Nuclear wastes are hazardous for tens of thousands of years. This clearly is unprecedented and poses a huge threat to our future generations.
- 6. 就算將核廢料做深地質處置，核廢料還是有可能出現並威脅我們的後代。
- 6. Even if put into a geological repository, the waste might emerge and threaten future generations.
- 7. 人造的輻射與自然輻射有所不同。
- 7. Man-made radiation differs from natural radiation.
- 8. 沒有人知道處理核廢料的真正成本，其代價過高以致於核能發電根本不經濟。
- 8. Nobody knows the true costs of waste management. The costs are so high that nuclear power can never be economic.
- 9. 核廢料應該被丟棄到太空。
- 9. The waste should be disposed of into space.
- 10. 應該要將核廢料人工轉變為其他無害的物質。
- 10. Nuclear waste should be transmuted into harmless materials.
1. 核能產業仍然無法處理「核廢料問題」 The nuclear industry still has no solution to the 'waste problem'
許多人理所當然地覺得，核能產業還沒有能力處理核廢料，所以不應該繼續運作。然而，事實上核能產業已經發展所需的科技，並且多數科技已經進入應用階段，剩下的議題是如何讓大眾接受他們所提出的解決方法。 Many people quite reasonably feel that the nuclear industry shouldn't continue operation without having a solution for the disposal of its radioactive waste. However, the industry has in fact developed the necessary technologies and implemented most of them - the remaining issue is to ensure that the proposed solutions are acceptable to the public.
Today, safe management practices are implemented or planned for all categories of radioactive waste. Low-level waste (LLW) and most intermediate-level waste (ILW), which make up most of the volume of waste produced (97%), are being disposed of securely in near-surface repositories in many countries so as to cause no harm or risk in the long-term. This practice has been carried out for many years in many countries as a matter of routine.
High-level waste (HLW) is currently safely contained and managed in interim storage facilities. The amount of HLW produced (including used fuel when this is considered a waste) is in fact small in relation to other industry sectors. HLW is currently increasing by about 12,000 tonnes worldwide every year, which is the equivalent of a two-storey structure built on a basketball court or about 100 double-decker buses and is modest compared with other industrial wastes. The use of interim storage facilities currently provides an appropriate environment in which to contain and manage this amount of waste. These facilities also allow for the heat and radioactivity of the waste to decay prior to long-term geological disposal. In fact, after 40 years there is only about one thousandth as much radioactivity as when the reactor is switched off to unload the used fuel. Interim storage provides an appropriate means of storing used fuel until a time when that country has sufficient fuel to make a repository development economic.
In the long-term however, appropriate disposal arrangements are required for HLW, due to its prolonged radioactivity. Disposal solutions are currently being developed for HLW that are safe, environmentally sound and publicly acceptable. The solution that is widely accepted as feasible is deep geological disposal, and repository projects are well advanced in some countries, such as Finland, Sweden and the USA. In fact, in the USA a deep geological waste repository (the Waste Isolation Pilot Plant) is already in operation in New Mexico for the disposal of transuranic waste (long-lived ILW contaminated with military materials such as plutonium), although Nevada is showing classic Nimbya resistance to the proposed Yucca Mountain repository. These countries have demonstrated that political and public acceptance issues at a community and national level can be met.
The nuclear industry therefore has clearly defined waste disposal methods for all waste produced and is making progress in many countries to achieve public acceptance of the approved programmes. It is important that other governments in nuclear energy-producing countries now follow the lead set by these countries on the issue of long-term disposal of high-level radioactive waste.
With the availability of technologies and the continued progress being made to develop publicly acceptable sites, it is logical that construction of new nuclear facilities can continue. Nuclear energy has distinct environmental advantages over fossil fuels. As well as containing and managing virtually all its wastes, nuclear power stations do not cause any pollution. The fuel for nuclear power is virtually unlimited, considering both geological and technological aspects. There is plenty of uranium in the Earth's crust and furthermore, well-proven (but not yet fully economic) technology means that we can extract about 60 times as much energy from it as we do today. The safety record of nuclear energy is better than for any major industrial technology. All these benefits should be taken into account when considering the construction of new facilities.
2. 核廢料的運送過程會對人類與環境造成危害 The transportation of this waste poses an unacceptable risk to people and the environment
Nuclear materials have been transported safely (virtually without incident and without harmful effect on anyone) since before the advent of nuclear power over 50 years ago. Transportations of nuclear materials cannot therefore be referred to as 'mobile Chernobyls'.
The primary assurance of safety in the transport of nuclear materials is the way in which they are packaged. Packages that store waste during transportation are designed to ensure shielding from radiation and containment of waste, even under the most extreme accident conditions. Since 1971, there have been more than 20,000 safe shipments of highly radioactive used fuel and high-level wastes (over 50,000 tonnes) over more than 30 million kilometres (about 19 million miles) with no property damage or personal injury, no breach of containment, and very low radiation dose to the personnel involved.
3. 「鈾」是世界上對危險的成分 Plutonium is the most dangerous material in the world
Plutonium has been stated to be 'the most toxic substance on earth' and so hazardous that 'a speck can kill'. Plutonium is indeed toxic and therefore must be handled in a responsible manner. Its hazard is principally associated with the ionising radiation it emits. However, it is primarily hazardous if inhaled in small particles.
Comparisons between toxic substances are not straightforward since the effect of plutonium inhalation would be to increase the probability of a cancer in several years time, whilst most other toxins lead to immediate death. Best comparisons indicate that, gram for gram, toxins such as ricin and some snake venoms and cyanide are significantly more toxic. Consider also that all the cleaning products that we have in our kitchen are toxic if we absorb them, whilst some of the products that are spread onto crops are toxic as well.
4. There is a potential terrorist threat to the large volumes of radioactive wastes currently being stored and the risk that this waste could leak or be dispersed as a result of terrorist action
High-level waste (HLW) and used fuel is kept in secure nuclear facilities with appropriate protection measures. Most high-level wastes produced are held as stable ceramic solids or in vitrified form (glass), designed to ensure that radioactive isotopes resulting from the nuclear reaction are retained securely in the glass or ceramic. Their structure is such that they would be very difficult to disperse by terrorist action, so that the threat from so-called 'dirty bombs' is not high.
The US Nuclear Regulatory Commission (NRC) has responded to suggestions that spent fuel is vulnerable to terrorist actions and should be put into dry storage casks after five years: "Nuclear power reactor spent fuel pools are neither easily reached nor easily breached. Instead, they are strong structures constructed of very thick steel-reinforced concrete walls with stainless steel liners. In addition, other design characteristics of these pools, not analyzed in the paper, can make them highly resistant to damage and can ease the ability to cope with any damage. Such characteristics can include having the fuel in the pool partially or completely below grade and having the pool shielded by other plant structures."b
A report released on June 25, 2002 by the National Academy of Sciences, concludes that if a dirty bomb attack were to occur, "the casualty rate would likely be low, and contamination could be detected and removed from the environment, although such cleanup would probably be expensive and time consuming." The disruption caused by such an attack would result from public fear of anything 'nuclear', and thus "the ease of recovery...would depend to a great extent on how the attack was handled by first responders, political leaders, and the news media, all of which would help to shape public opinion and reactions."c
The International Atomic Energy Agency (IAEA) has identified medical and industrial radioactive sources as posing considerable concern in terms of potential terrorist threats from their use in 'dirty bombs'. The need for stronger controls to prevent the theft or loss of control of powerful radiological sources and hence ensure their safety and security has been highlighted as of paramount importance.
Making the Nation Safer: The Role of Science and Technology in Countering Terrorism, Committee on Science and Technology for Countering Terrorism, National Research Council of the National Academies, The National Academies Press (ISBN: 9780309084819)
IAEA Security of Radioactive Sources webpage (www-ns.iaea.org/security/sources.htm)
NRC Nuclear Security and Safeguards webpage (www.nrc.gov/security.html)
5. 核廢料經過萬年之後仍然有害，這對於我們的後代是長遠的威脅 Nuclear wastes are hazardous for tens of thousands of years. This clearly is unprecedented and poses a huge threat to our future generations in the long-term
Many industries produce hazardous waste. The nuclear industry has developed technology that will ensure its hazardous waste can be managed appropriately so as to cause no risk to future generations.
In fact, the radioactivity of nuclear wastes naturally decays progressively and has a finite radiotoxic lifetime. The radioactivity of high-level wastes decays to the level of an equivalent amount of original mined uranium ore in between 1,000 and 10,000 years. Its hazard then depends on how concentrated it is. Compare this to other industrial wastes (e.g. heavy metals such as cadmium and mercury), which remain hazardous indefinitely.
Most nuclear wastes produced are hazardous, due to their radioactivity, for only a few tens of years and are routinely disposed in near-surface disposal facilities. A small volume of nuclear waste (~3% volume of total waste produced) is long-lived and highly radioactive and requires isolation from the environment for many thousands of years.
International conventions define what is hazardous in terms of radiation dose, and national regulations limit allowable doses accordingly. Well-developed industry technology ensures that these regulations are met so that any hazardous wastes are handled in a way that poses no risk to human health or the environment. Waste is converted into a stable form that is suitable for disposal. In the case of high-level waste, a multi-barrier approach, combining containment and geological disposal, ensures isolation of the waste from people and the environment for thousands of years.
6. Even if put into a geological repository, the waste might emerge and threaten future generations
The reality is that with today's spent fuel or vitrified high-level waste (HLW), extra layers of protection come from the multi-barriers of stable ceramic material, encapsulation, and depth from the biosphere that are designed to prevent any movement of radioactivity for thousands of years. A stable geological formation, within which the waste will be disposed, also constitutes a highly reliable barrier.
Radiation scientists, geologists and engineers have produced detailed plans for safe underground storage of nuclear waste and some are now operating. Geological repositories for HLW are designed to ensure that harmful radiation would not reach the surface even with severe earthquakes or the passage of time.
Nature has also provided good examples of nuclear waste 'storage'. About two billion years ago, in what is now Gabon in Africa, a rich natural uranium deposit produced spontaneous, large nuclear reactions which ran for many years. Since then, despite thousands of centuries of tropical rain and subsurface water, the long-lived radioactive 'waste' from those 'reactors' has migrated less than 10 metres. Furthermore, deposits of uranium ore exist underground without any expression of this by release of radionuclides at the surface (e.g. at Cigar Lake in Canada and Olympic Dam in South Australia).
7. 人造的輻射與自然輻射有所不同 Manmade radiation differs from natural radiation
Radiation emitted from manmade radionuclides is exactly the same form as radiation emitted from naturally-occurring radioactive materials (namely alpha, beta or gamma radiation). As such, the radiation emitted by naturally-occurring materials can not be distinguished from radiation produced by materials in the nuclear fuel cycle.
Most elements have a radioactive form (radioisotope) and many of these occur naturally. We live our lives surrounded by naturally-radioactive materials, and are constantly bathed in radiation originating in the rocks and soil, building materials, the sky (space), food and one another. A typical background level of exposure is 2-3 millisieverts per year (mSv/y). Regulations limit extra exposure from man-made radiation due to human activities (other than medicine) to 1 mSv/y for members of the public and average 20 mSv/y for occupational exposure. These levels are very seldom exceeded, though no harm has been shown for levels up to 50 mSv/y. Some people are exposed to lifelong natural background levels which are higher than this.
8. 沒有人知道處理核廢料的真正代價，其成本過高使得核能發電根本不經濟 Nobody knows the true costs of waste management. The costs are so high that nuclear power can never be economic
Because it is widely accepted that producers of radioactive wastes should bear the costs of disposal, most countries with nuclear power programmes make estimates of the costs of disposal and update these periodically. International organisations such as the Nuclear Energy Agency (NEA) of the Organisation for Economic Co-operation and Development (OECD) have also coordinated exercises to compare these estimates with one another. For low-level waste, the costs are well-known because numerous facilities have been built and have operated for many years around the world. For high level-waste (HLW), cost estimates are becoming increasingly reliable as projects get closer to implementation.
Based on the estimated total costs of managing nuclear wastes, many countries require that the operators of nuclear power plants set aside funding to cover all costs. Different mechanisms exist in different countries. Although the sum already deposited in dedicated funds are high, the costs of waste management do not drastically increase the price of electricity. Typically the spent fuel management and disposal costs represent about 10% of the total costs involved in producing electricity from a nuclear power plant. Thus, although the absolute costs of waste management are high, they do not render the nuclear fuel cycle uneconomic, because of the high ratio of revenue earned to waste volumes produced.
9. 核廢料應該丟棄到太空 The waste should be disposed of into space
The option of disposal of waste into space has been examined repeatedly since the 1970s. This option has not been implemented and further studies have not been performed because of the high cost of this option and the safety aspects associated with the risk of launch failure.
Other ideas for disposal section in Waste Management in the Nuclear Fuel Cycle Appendix 2: Storage and Disposal Options
10. 應該將核廢料遷變為無害的物質 Nuclear waste should be transmuted into harmless materials
Transmutation is the process of transforming one radionuclide into another via neutron bombardment in a nuclear reactor or accelerator-driven device. The objective is to change long-lived actinides and fission products into significantly shorter-lived nuclides. The goal is to have wastes that become radiologically harmless in only a few hundred years.
Transmutation is not feasible for all of the wastes produced in the past or to be produced. Transmutation may be able to reduce waste quantities but it will do it only to a certain extent and therefore not eliminate the need for disposal. One of the technical issues is to isolate each nuclide (partitioning) so that it can then be irradiated, otherwise the process is likely to create as much waste as it destroys. Even if the economics of partitioning and transmutation were favourable, it is likely that the benefits would not compensate for the burden of additional operations required for separating and transmuting only part of the nuclides.
Nuclear Energy Agency's webpage on Partitioning and Transmutation of Minor Actinides and Fission Products (www.nea.fr/html/pt/welcome.html)
a. Nimby is an acronym for 'not in my back yard', and refers to opposition by local residents to a new development. [Back]
b. The quote is from NRC Review of Paper on Reducing Hazards From Stored Spent Nuclear Fuel, US NRC Fact Sheet (August 2003). The Fact Sheet was published in response to the paper Reducing the Hazards from Stored Spent Power-Reactor Fuel in the United States, Robert Alvarez et al, Science and Global Security, 11:1–51 (2003). See also Remarks by Commissioner Edward McGaffigan, Jr., U.S. Nuclear Regulatory Commission, Regulatory Information Conference, Washington, D.C. (17 April 2003) [Back]
c. The quote is taken from Chapter 2, Nuclear and Radiological Threats, of Making the Nation Safer: The Role of Science and Technology in Countering Terrorism, The National Academies Press (ISBN: 9780309084819) [Back]
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