Financing for renewable energy is already scarce, and increasing nuclear capacity will only add to the competition for funding. Going down the nuclear route would mean that poor countries, that don't have the financial resources to invest in and develop nuclear power, would become reliant on rich, technologically advanced nations.
Alternatively, poor nations without experience in the building and maintaining of nuclear plants may decide to build them anyway. Countries with a history of nuclear power use have learned the importance of regulation, oversight, and investment in safety when it comes to nuclear.
Peter Bradford of Vermont Law, a former member of the US Nuclear Regulatory Commission, writes, "A world more reliant on nuclear power would involve many plants in countries that have little experience with nuclear energy, no regulatory background in the field and some questionable records on quality control, safety and corruption.
The U. Please also see the piece Nuclear Energy is not a Climate Solution. Anspaugh, Gilbert W. Drozdovitch, Vera Garber, Yuri I. Gavrilin, Valeri T.
Khrouch, Arthur V. Kuvshinnikov, Yuri N. Kuzmenkov, Victor P. Minenko, Konstantin V. Moschik, Alexander S. Nalivko, Jacob Robbins, Elena V. Shemiakina, Sergei Shinkarev, Svetlana I. Tochitskaya, Myron A. Waclawiw, and Andre Bouville. Leukemia in the proximity of a boiling-water nuclear reactor: Evidence of population exposure by chromosome studies and environmental radioactivity.
Environmental Health Perspectives : World Nuclear Industry, July Water is life. Some of us drink it straight from our faucet without a second thought. Others go to great lengths to buy enough jugs or bottles from the store to always have on hand. At the other extreme are those who say low levels of radiation are actually good for you. There's a good discussion on the evidence of the effects of low level radiation here.
But you are probably wondering why can't we say for certain which of these positions is correct when it comes to low doses of radiation. The answer is simple: the evidence isn't clear because the effects of low dose radiation are so rare they are very difficult to measure. As the UK anti-nuclear power pressure group no2nuclearpower says, "there is no such thing as an absolutely safe level of radiation: all exposures no matter how small entail some risk - even background radiation.
So, the question is how do the risks of low doses of radiation compare with other risks. Let's start with the seminal report on Chernobyl's legacy produced by the World Health Organization WHO - another very reputable body - in It predicted that some 9, people were likely to die from low level radiation exposure as a result of the accident.
Remember, this is an estimate of deaths. As we have seen only 43 people died of cancers that could be directly linked to radiation exposure. Nevertheless, it is a frightening figure but we need to see it in context. These likely casualties represent a tiny fraction the almost seven million people the WHO assumes were exposed to radiation. And remember how common cancer is. About half of people in developed nations will develop cancer during their lifetime ; a quarter of us can expect to die from it.
The WHO says that, even amongst the , people most affected by the disaster the increase in cancer caused by radiation will be "difficult to observe" because so many people will develop other cancers.
So, when it comes to all seven million people affected by fallout from Chernobyl it should be no surprise to discover that it says there's no chance of cancers caused by the disaster being identified.
It confirms what most radiation experts say: exposure to low levels of radiation is not a major health risk. Don't get them wrong, they are not saying those deaths aren't important - of course they are. But so are the other roughly 1. The American Cancer Society, for example, estimates that smoking causes one out of five of all deaths in the US and we know that things like bad diet, inactivity, obesity and alcohol can also cause cancer.
What the findings of the WHO report confirm is that other factors like these pose far greatest cancer risks to us all - even those of us who had the misfortune to be exposed to low levels of radiation from Chernobyl. What this suggests is that we should focus our efforts on tackling them, and perhaps worry a bit less about the potential effects of low levels of radiation from things like nuclear accidents. Of course, the fear of radiation isn't the only reason people oppose nuclear power - there are worries about the proliferation of nuclear weapons and waste disposal, not to mention the huge cost of building new nuclear power stations and then decommissioning them.
But here's the thing: if we were a bit less concerned about the risks of low levels of radiation then maybe we could make a more balanced assessment of nuclear power. Especially given that coal-fired power stations routinely release more radioactivity into the environment than nuclear power stations, thanks to the traces of uranium and thorium found in coal. And, since we are talking about worrying about the right things, let's not forget the environment.
Taking a more balanced view on the risks of radiation might help all those anxious climate scientists I mentioned at the start of this piece sleep a bit easier in their beds at night.
Follow Justin on Twitter. I've travelled all over the world for the BBC and seen evidence of environmental damage and climate change everywhere. It's the biggest challenge humanity has ever faced.
Tackling it means changing how we do virtually everything. We are right to be anxious and afraid at the prospect, but I reckon we should also see this as a thrilling story of exploration, and I'm delighted to have been given the chance of a ringside seat as chief environment correspondent. Image source, Getty Images. Nuclear nightmares. Chernobyl nuclear power plant a few weeks after the disaster in The real numbers.
Brace yourself. Two teenage victims of the Chernobyl nuclear disaster receive infrared radiation treatment. What about low-level radiation exposure? In the chemical industry and oil-gas industry, major accidents also lead to improved safety. There is wide public acceptance that the risks associated with these industries are an acceptable trade-off for our dependence on their products and services. With nuclear power, the high energy density makes the potential hazard obvious, and this has always been factored into the design of nuclear power plants.
The few accidents have been spectacular and newsworthy, but of little consequence in terms of human fatalities.
The novelty value and hence newsworthiness of nuclear power accidents remains high in contrast with other industrial accidents, which receive comparatively little news coverage. In the s attention turned to harnessing the power of the atom in a controlled way, as demonstrated at Chicago in and subsequently for military research, and applying the steady heat yield to generate electricity.
This naturally gave rise to concerns about accidents and their possible effects. However, with nuclear power, safety depends on much the same factors as in any comparable industry: intelligent planning, proper design with conservative margins and back-up systems, high-quality components and a well-developed safety culture in operations.
The operating lives of reactors depend on maintaining their safety margin. A particular nuclear scenario was loss of cooling which resulted in melting of the nuclear reactor core, and this motivated studies on both the physical and chemical possibilities as well as the biological effects of any dispersed radioactivity. Those responsible for nuclear power technology in the West devoted extraordinary effort to ensuring that a meltdown of the reactor core would not take place, since it was assumed that a meltdown of the core would create a major public hazard, and if uncontained, a tragic accident with likely multiple fatalities.
In avoiding such accidents the industry has been very successful. In the year history of civil nuclear power generation, with over 18, cumulative reactor-years across 36 countries, there have been only three significant accidents at nuclear power plants:. Appendix 1: The Hazards of Using Energy contains a table showing all reactor accidents and a table listing some energy-related accidents with multiple fatalities.
Of all the accidents and incidents, only the Chernobyl and Fukushima accidents resulted in radiation doses to the public greater than those resulting from the exposure to natural sources. The Fukushima accident resulted in some radiation exposure of workers at the plant, but not such as to threaten their health, unlike Chernobyl. Other incidents and one 'accident' have been completely confined to the plant. Apart from Chernobyl, no nuclear workers or members of the public have ever died as a result of exposure to radiation due to a commercial nuclear reactor incident.
Most of the serious radiological injuries and deaths that occur each year deaths and many more exposures above regulatory limits are the result of large uncontrolled radiation sources, such as abandoned medical or industrial equipment. There have also been a number of accidents in experimental reactors and in one military plutonium-producing pile — at Windscale, UK, in — but none of these resulted in loss of life outside the actual plant, or long-term environmental contamination.
One of its functions was to act as an auditor of world nuclear safety, and this role was increased greatly following the Chernobyl accident. It prescribes safety procedures and the reporting of even minor incidents. Its role has been strengthened since see later section.
Every country which operates nuclear power plants has a nuclear safety inspectorate and all of these work closely with the IAEA. While nuclear power plants are designed to be safe in their operation and safe in the event of any malfunction or accident, no industrial activity can be represented as entirely risk-free. Incidents and accidents may happen, and as in other industries, what is learned will lead to a progressive improvement in safety. Those improvements are both in new designs, and in upgrading of existing plants.
The long-term operation LTO of established plants is achieved by significant investment in such upgrading. The safety of operating staff is a prime concern in nuclear plants. Radiation exposure is minimised by the use of remote handling equipment for many operations in the core of the reactor.
Other controls include physical shielding and limiting the time workers spend in areas with significant radiation levels. These are supported by continuous monitoring of individual doses and of the work environment to ensure very low radiation exposure compared with other industries. The use of nuclear energy for electricity generation can be considered extremely safe. Every year several hundred people die in coal mines to provide this widely used fuel for electricity.
There are also significant health and environmental effects arising from fossil fuel use. Contrary to popular belief, nuclear power saves lives by displacing fossil fuel from the electricity mix. Concerning possible accidents, up to the early s, some extreme assumptions were made about the possible chain of consequences.
These gave rise to a genre of dramatic fiction e. The China Syndrome in the public domain and also some solid conservative engineering including containment structures in the industry itself.
Licensing regulations were framed accordingly. It was not until the late s that detailed analyses and large-scale testing, followed by the meltdown of the Three Mile Island reactor, began to make clear that even the worst possible accident in a conventional western nuclear power plant or its fuel would not be likely to cause dramatic public harm.
The industry still works hard to minimize the probability of a meltdown accident, but it is now clear that no-one need fear a potential public health catastrophe simply because a fuel meltdown happens. Fukushima Daiichi has made that clear, with a triple meltdown causing no fatalities or serious radiation doses to anyone, while over two hundred people continued working onsite to mitigate the accident's effects.
The decades-long test and analysis programme showed that less radioactivity escapes from molten fuel than initially assumed, and that most of this radioactive material is not readily mobilized beyond the immediate internal structure. Thus, even if the containment structure that surrounds all modern nuclear plants were ruptured, as was the case with one of the Fukushima reactors, it is still very effective in preventing the escape of most radioactivity.
A mandated safety indicator is the calculated probable frequency of degraded core or core melt accidents. The US Nuclear Regulatory Commission NRC specifies that reactor designs must meet a theoretical 1 in 10, year core damage frequency, but modern designs exceed this. US utility requirements are 1 in , years, the best currently operating plants are about 1 in one million and those likely to be built in the next decade are almost 1 in 10 million.
While this calculated core damage frequency has been one of the main metrics to assess reactor safety, European safety authorities prefer a deterministic approach, focusing on actual provision of back-up hardware, though they also undertake probabilistic safety analysis PSA for core damage frequency, and require a 1 in 1 million core damage frequency for new designs. Even months after the Three Mile Island TMI accident in it was assumed that there had been no core melt because there were no indications of severe radioactive release even inside the containment.
It turned out that in fact about half the core had melted. Until this remained the only core melt in a reactor conforming to NRC safety criteria, and the effects were contained as designed, without radiological harm to anyone. At Fukushima in a different reactor design with penetrations in the bottom of the pressure vessel the three reactor cores evidently largely melted in the first two or three days, but this was not confirmed for about ten weeks.
The TMI accident proved the extent of truth in the proposition, and the molten core material got exactly 15 mm of the way to China as it froze on the bottom of the reactor pressure vessel. A few of these are gases at normal temperatures, more are volatile at higher temperatures, and both will be released from the fuel if the cladding is damaged. In addition, as cooling water was flushed through the hot core, soluble fission products such as caesium dissolved in it, which created the need for a large water treatment plant to remove them.
Apart from these accidents and the Chernobyl disaster there have been about ten core melt accidents — mostly in military or experimental reactors — Appendix 2 lists most of them. None resulted in any hazard outside the plant from the core melting, though in one case there was significant radiation release due to burning fuel in hot graphite similar to Chernobyl but smaller scale. The Fukushima accident should also be considered in that context, since the fuel was badly damaged and there were significant off-site radiation releases.
Licensing approval for new plants today requires that the effects of any core-melt accident must be confined to the plant itself, without the need to evacuate nearby residents. The main safety concern has always been the possibility of an uncontrolled release of radioactive material, leading to contamination and consequent radiation exposure off-site.
Earlier assumptions were that this would be likely in the event of a major loss of cooling accident LOCA which resulted in a core melt. The TMI experience suggested otherwise, but at Fukushima this is exactly what happened.
In the light of better understanding of the physics and chemistry of material in a reactor core under extreme conditions it became evident that even a severe core melt coupled with breach of containment would be unlikely to create a major radiological disaster from many Western reactor designs, but the Fukushima accident showed that this did not apply to all. Studies of the post-accident situation at TMI where there was no breach of containment supported the suggestion, and analysis of Fukushima will be incomplete until the reactors are dismantled.
Certainly the matter was severely tested with three reactors of the Fukushima Daiichi nuclear power plant in Japan in March Cooling was lost about an hour after a shutdown, and it proved impossible to restore it sufficiently to prevent severe damage to the fuel.
The reactors, dating from , were written off. A fourth is also written off due to damage from a hydrogen explosion. A fundamental principle of nuclear power plant operation worldwide is that the operator is responsible for safety. The national regulator is responsible for ensuring the plants are operated safely by the licensee, and that the design is approved.
Design certification of reactors is also the responsibility of national regulators. There is international collaboration among these to varying degrees, and there are a number of sets of mechanical codes and standards related to quality and safety. With new reactor designs being established on a more international basis since the s, both the industry and regulators are seeking greater design standardization and also regulatory harmonization. Earlier designs however have been progressively upgraded through their operating lives.
It has long been asserted that nuclear reactor accidents are the epitome of low-probability but high-consequence risks. Understandably, with this in mind, some people were disinclined to accept the risk, however low the probability. However, the physics and chemistry of a reactor core, coupled with but not wholly depending on the engineering, mean that the consequences of an accident are likely in fact be much less severe than those from other industrial and energy sources.
Experience, including Fukushima, bears this out. A US Department of Energy DOE Human Performance Handbook notes: "The aviation industry, medical industry, commercial nuclear power industry, US Navy, DOE and its contractors, and other high-risk, technologically complex organizations have adopted human performance principles, concepts, and practices to consciously reduce human error and bolster controls in order to reduce accidents and events Clearly, focusing efforts on reducing human error will reduce the likelihood of events.
To achieve optimum safety, nuclear plants in the western world operate using a 'defence-in-depth' approach , with multiple safety systems supplementing the natural features of the reactor core. Key aspects of the approach are:. These can be summed up as: prevention, monitoring, and action to mitigate consequences of failures.
The safety provisions include a series of physical barriers between the radioactive reactor core and the environment, the provision of multiple safety systems, each with backup and designed to accommodate human error.
As well as the physical aspects of safety, there are institutional aspects which are no less important — see following section on International Collaboration. The barriers in a typical plant are: the fuel is in the form of solid ceramic UO 2 pellets, and radioactive fission products remain largely bound inside these pellets as the fuel is burned.
The pellets are packed inside sealed zirconium alloy tubes to form fuel rods. These are confined inside a large steel pressure vessel with walls up to 30 cm thick — the associated primary water cooling pipework is also substantial. All this, in turn, is enclosed inside a robust reinforced concrete containment structure with walls at least one metre thick.
This amounts to three significant barriers around the fuel, which itself is stable up to very high temperatures. These barriers are monitored continually. The fuel cladding is monitored by measuring the amount of radioactivity in the cooling water.
The high pressure cooling system is monitored by the leak rate of water, and the containment structure by periodically measuring the leak rate of air at about five times atmospheric pressure. The main safety features of most reactors are inherent — negative temperature coefficient and negative void coefficient. The first means that beyond an optimal level, as the temperature increases the efficiency of the reaction decreases this in fact is used to control power levels in some new designs.
The second means that if any steam has formed in the cooling water there is a decrease in moderating effect so that fewer neutrons are able to cause fission and the reaction slows down automatically. In the s and s some experimental reactors in Idaho were deliberately tested to destruction to verify that large reactivity excursions were self-limiting and would automatically shut down the fission reaction.
These tests verified that this was the case. Beyond the control rods which are inserted to absorb neutrons and regulate the fission process, the main engineered safety provisions are the back-up emergency core cooling system ECCS to remove excess heat though it is more to prevent damage to the plant than for public safety and the containment.
Traditional reactor safety systems are 'active' in the sense that they involve electrical or mechanical operation on command. Some engineered systems operate passively, e. Both require parallel redundant systems. Inherent or full passive safety design depends only on physical phenomena such as convection, gravity or resistance to high temperatures, not on functioning of engineered components. All reactors have some elements of inherent safety as mentioned above, but in some recent designs the passive or inherent features substitute for active systems in cooling etc.
Such a design would have averted the Fukushima accident, where loss of electrical power resulted is loss of cooling function. The basis of design assumes a threat where due to accident or malign intent e. This double possibility has been well studied and provides the basis of exclusion zones and contingency plans. Apparently during the Cold War neither Russia nor the USA targeted the other's nuclear power plants because the likely damage would be modest.
Nuclear power plants are designed with sensors to shut them down automatically in an earthquake, and this is a vital consideration in many parts of the world. See Nuclear Power Plants and Earthquakes paper. In addition to engineering and procedures which reduce the risk and severity of accidents, all plants have guidelines for severe accident management or mitigation SAM.
These conspicuously came into play after the Fukushima accident, where staff had immense challenges in the absence of power and with disabled cooling systems following damage done by the tsunami.
The experience following that accident is being applied not only in design but also in such guidelines, and peer reviews on nuclear plants are focusing more on these than previously.
In mid the IAEA Incident and Emergency Centre launched a new secure web-based communications platform to unify and simplify information exchange during nuclear or radiological emergencies. The Unified System for Information Exchange on Incidents and Emergencies USIE has been under development since but was actually launched during the emergency response to the accident at Fukushima. In both the TMI and Fukushima accidents the problems started after the reactors were shut down — immediately at TMI and after an hour at Fukushima, when the tsunami arrived.
The need to remove decay heat from the fuel was not met in each case, so core melting started to occur within a few hours. Cooling requires water circulation and an external heat sink.
If pumps cannot run due to lack of power, gravity must be relied upon, but this will not get water into a pressurised system — either reactor pressure vessel or containment. Hence there is provision for relieving pressure, sometimes with a vent system, but this must work and be controlled without power.
There is a question of filters or scrubbers in the vent system: these need to be such that they do not block due to solids being carried. Ideally any vent system should deal with any large amounts of hydrogen, as at Fukushima, and have minimum potential to spread radioactivity outside the plant. Filtered containment ventilation systems FCVSs have been retrofitted to some reactors which did not already have them, or any of sufficient capacity, following the Fukushima accident.
The basic premise of a FCVS is that, independent of the state of the reactor itself, the catastrophic failure of the containment structure can be avoided by discharging steam, air and incondensable gases like hydrogen to the atmosphere.
The Three Mile Island accident in demonstrated the importance of the inherent safety features. Despite the fact that about half of the reactor core melted, radionuclides released from the melted fuel mostly plated out on the inside of the plant or dissolved in condensing steam. The containment building which housed the reactor further prevented any significant release of radioactivity.
The accident was attributed to mechanical failure and operator confusion. The reactor's other protection systems also functioned as designed.
The emergency core cooling system would have prevented any damage to the reactor but for the intervention of the operators. Investigations following the accident led to a new focus on the human factors in nuclear safety.
No major design changes were called for in western reactors, but controls and instrumentation were improved significantly and operator training was overhauled.
At Fukushima Daiichi in March the three operating reactors shut down automatically, and were being cooled as designed by the normal residual heat removal system using power from the back-up generators, until the tsunami swamped them an hour later.
The emergency core cooling systems then failed. Days later, a separate problem emerged as spent fuel ponds lost water. Analysis of the accident showed the need for more intelligent siting criteria than those used in the s, and the need for better back-up power and post-shutdown cooling, as well as provision for venting the containment of that kind of reactor and other emergency management procedures.
See section below. In the US NRC launched a research program to assess the possible consequences of a serious reactor accident. Its draft report was released nearly a year after the Fukushima accident had partly confirmed its findings. SOARCA's main conclusions fall into three areas: how a reactor accident progresses; how existing systems and emergency measures can affect an accident's outcome; and how an accident would affect the public's health.
The principal conclusion is that existing resources and procedures can stop an accident, slow it down or reduce its impact before it can affect the public, but even if accidents proceed without such mitigation they take much longer to happen and release much less radioactive material than earlier analyses suggested.
This was borne out at Fukushima, where there was ample time for evacuation — three days — before any significant radioactive releases. This was the result of research and analysis undertaken to address concerns raised during public hearings in on the environmental assessment for the refurbishment of Ontario Power Generation's OPG's Darlington nuclear power plant.
The study involved identifying and modelling a large atmospheric release of radionuclides from a hypothetical severe nuclear accident at the four-unit Darlington power plant; estimating the doses to individuals at various distances from the plant, after factoring in protective actions such as evacuation that would be undertaken in response to such an emergency; and, finally, determining human health and environmental consequences due to the resulting radiation exposure.
It concluded that there would be no detectable health effects or increase in cancer risk. A fuller write-up of it is on the World Nuclear News website. The April disaster at the Chernobyl nuclear power plant in Ukraine was the result of major design deficiencies in the RBMK type of reactor, the violation of operating procedures and the absence of a safety culture.
One peculiar feature of the RBMK design was that coolant failure could lead to a strong increase in power output from the fission process positive void coefficient. However, this was not the prime cause of the Chernobyl accident. It once and for all vindicated the desirability of designing with inherent safety supplemented by robust secondary safety provisions.
By way of contrast to western safety engineering, the Chernobyl reactor did not have a containment structure like those used in the West or in post Soviet designs.
The accident destroyed the reactor, and its burning contents dispersed radionuclides far and wide.
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