Table of Contents:
From a public perspective, the biggest concern is the possibility of an accident. To date, there have been three nuclear accidents: Three Mile Island, Chernobyl and Fukushima Daiichi. The public’s perception of these events has resulted in a persuasive anti-nuclear advocacy. Unfortunately, there is a strong misunderstanding of these accidents and their impact on people and the environment.
The accident at Thr ee Mile Island occurred in March of 1979 and resulted in near complete destruction of the fuel in the reactor. The resulting meltdown of the fuel allowed dangerous highly radioactive fission products to escape into the reactor building where ahnost all were contained. Very little, most notably radioactive noble gasses and some radioactive iodine, escaped to the environment. It was estimated that the release of the radionuclides could result in one extra cancer death in the population within 50 miles of Three Mile Island. Within this population of 2.2 million it was expected there would be about
540,000 cancers and 325,000 cancer deaths, not counting the accident (Battist, 1979). While some studies disagree, the principle health effect of the accident was the mental stress on the residents and not diseases associated with radiation. The stress was believed to have resulted in an increase in heart problems within the area around Three Mile Island.
In a long-term study performed by the University of Pittsburgh, it was concluded that there were health effects related to the accident. Specifically, there was an increase in mortality due to heart attacks among the group studied. At that time, they could not rule out the possibility of long latency period cancers (Talbott et al., 2000). Another series of studies found there was long term stress among the residents surrounding Three Mile Island and that such chronic stress could cause a variety of physical, emotional, and mental illnesses (Osif, 2004). More recent work suggests the low levels the residents around Three Mile Island were exposed to could explain certain anomalies observed in thyroid cancers within the group (Goldenberg, 2017). Others suggest these could be associated with the levels of radioactive iodine produced by nuclear weapons testing and suggest that additional studies be performed (Mangano and
Sherman, 2019). While one cannot say with absolute certainty there were no radiological implications from the low levels of radioactivity released, it seems there is no strong evidence to support the case that there were. Nonetheless, despite a near complete meltdown of the reactor, and a near worst case accident, the health effects appear minimal and are largely associated with the stress of events. Studies are ongoing and will likely continue for years.
By comparison, the accident at the Chernobyl reactor was much more severe, owing to the design and the lack of safety features commonly found in Western reactors. The Chernobyl reactor lacked the containment building which would have housed the nuclear reactor and associated equipment. A containment building would have held back almost all of the radioactive material in the accident.
The Chernobyl accident occurred during a physics tests that caused the reactor power to increase so rapidly that the cooling water vaporized almost instantaneously causing a sudden explosive buildup of steam. Temperatures in the reactor got so hot that the carbon used to help the nuclear reaction caught fire and the fuel melted. The result was a radioactive plume that spread throughout the surrounding area. Twenty-eight firefighters received deadly radiation doses and died. It is reasonably clear that those involved in the emergency work after the explosions suffered an increase in cancers and some circulatory issues. Similar circulatory issues were also seen at TMI among the general population near TMI. The cancers are thought to be due to the radiation dose received during the emergency. It is unclear what caused the circulatory issues. Nonetheless, the total impact on mortality was small despite what was probably the worst accident possible at a reactor, a completely uncontained release of radioactive material from the core. The World Health Organization estimates that among the 49,000 workers studied, there were about 200 deaths associated with the accident out of the nearly 5,000 deaths that occurred within this group. It should be remembered that these were the first responders and the emergency workers who fought the fire and experienced high radiation doses as a result (WHO, 2006).
Now, more than 30 years later, the general population surrounding the reactor has not seen a statistically significant increase in cancer deaths. There has been a statistically significant increase in thyroid cancers, probably as a result of the radioactive iodine released during the accident. It is expected that if the number of health effects is in proportion to the radiation dose received, there will be an additional
4,000 cancer deaths in the exposed population of 600,000. In a population of 600,000, one would expect about 200,000 cancer deaths over the lifespan of the population had the accident not occurred. To date, aside from an increase in thyroid cancers, there has not been an increase in cancer deaths in the exposed population. Studies are ongoing (WHO, 2016).
The most recent accident occurred at the Fukushima Daiichi nuclear power plant in Japan on March 11, 2011. The accident was the result of an earthquake and the resulting tsunami that occurred off the coast of Japan. The tsunami killed over 20,000 people and caused extensive damage all along the coast, including to the Fukushima Daiichi nuclear reactor’s safety systems. The damage to those systems resulted in a complete loss of electrical power at the site, including the backup diesel generators. The safety systems intended to cool the reactor in the event of an unusual occurrence are run by electrical power. Because there was no electricity, four of the six reactors at the site overheated and their reactor cores melted, releasing radioactive material. When the fuel overheated, the protective fuel cladding underwent oxidation, resulting in the generation of large quantities of hydrogen. The hydrogen built up in the reactor containments detonated, damaging the containments and releasing radioactive material to the environment.
The accident was extremely severe, however, unlike Chernobyl, the population near the site and even the workers on-site received much smaller doses of radiation. Despite the low levels of radiation offsite, over 100,000 people were evacuated. The evacuation resulted in 1,000 unnecessary deaths due in part to inadequate medical care for critically ill evacuees and the elderly. Similar fatalities were noted among those evacuated because of the earthquake and tsunami. Experts concluded that the evacuation was unnecessary, since radiation levels were similar to background levels elsewhere in the world (Hasegawa etal., 2015).
The accident at Three Mile Island and the events at Fukushima Daiichi demonstrate the importance of the safety built into the design of current nuclear power plants. While the reactor and associated systems in both suffered extreme damage and will require cleanup that will last for decades, the offsite consequences were minimal. By comparison, without those built-in safety features, the accident at Chernobyl created significant off-site radioactive contamination of the surrounding area and an increase in thyroid cancer.
The process of uranium fission produces both short-lived and long-lived radioactive material. These materials must be disposed of in a maimer such that they do not pose a risk to humans or the environment. Presently disposal methods and sites are available for all but the spent fuel. These materials consist of clothing, equipment, and chemicals that have become contaminated with radioactive materials duiing the operation, maintenance, and decommissioning of nuclear power plants. Such facilities are licensed by the U.S. NRC and provide reasonable assurance that there is minimal risk to the environment and human beings for at least as long as they remain a hazard.
Disposal of the spent fuel itself is still an open question in the U.S. The Nuclear Waste Policy Act designated deep geological disposal as the method for the disposal of spent fuel. Yucca Mountain was designated as the disposal site, pending evaluation and licensing. The site is located in Nevada, about 25 miles from Death Valley and 90 miles from Las Vegas. Due to opposition from the State and public opposed to having Nevada become the site for the nation’s spent fuel disposal site, the process is stalled for lack of Congressional funding. Spent fuel is currently stored onsite at both operating reactors and those that have been decommissioned. For operating reactors, some of the fuel is stored in pools until it’s cool enough to be placed in canisters and removed to dry storage. In the case of decommissioned reactors, the fuel is sufficiently cool so that it can be stored onsite in dry cask storage facility. As of this writing, the U.S. Congress has no plans to move forward with funding of Yucca Mountain as required by the Nuclear Waste Policy Act.
Other countries are moving forward with planning for the disposal of spent fuel. France, through a national referendum, authorized the expenditure of 25 billion Euro to construct a 500 m underground rock laboratory in eastern France situated in clays and known as the Industrial Centre for Geological Storage (C’igeo). The structure will comprise hundreds of storage tunnels covering a total area of 25 km2 and will last for a century. The project would provide a facility not unlike the Yucca Mountain Project to store but allow for retrieval of spent fuel for possible reprocessing into new fuel. As in the U.S., though there is strong opposition despite the referendum passing to the project.
In Sweden, the Svensk Kambranslehantering AB or SVK is tasked with developing a spent fuel repository (Figure 1). Like the French repository, the Swedish repository uses deep geological disposal in bedrock.
The proposed repository is currently under licensing review by the Swedish Radiation Safety Authority. Current plans call for the facility to be operational in 2030. It is estimated the complete program will cost about SWK 141 billion (14.1 billion USS).
Both of these countries have examined the problem and har e largely completed their safety and environmental reviews, concluding that deep geologic disposal is the preferred method of disposing of spent fuel. The U.S. proposal for Yucca Mountain is similar, technically, but is held up by the lack of support from the State of Nevada and its Congressional delegation. It’s worth noting that Nye County, where the facility would be located, strongly supports continuing with the project design and safety assessment. Tire County would support construction if the final safety and environmental analysis concludes the furl could be safely stored at Yucca Mountain for generations to come.
Why Should Nuclear be Used?
Looking at fossil fueled power plants, the emissions from fossil fuel electric generation plants result in a variety of pollutants: Sulfur dioxide (SO,), nitrous oxide (NOx), particulate material and heaty metals. Sulfur dioxide causes acid rain, which is hannfitl to plants and to animals that live in water. SO, also worsens respiratory ilhresses and heart diseases, particularly in children and the elderly. Nitrous oxide contributes to ground-level ozone, which irritates and damages the lungs. Particulate matter (PM) results in smog in cites and scenic areas. Coupled with ozone. PM contributes to asthma and chronic bronchitis, especially in children and the elderly. Very small, or fine PM. is also believed to cause emphysema and lung cancer. Heavy metals, such as mercury, are hazardous to human and animal health.
Estimates of the effect of burning fossil fuels suggest that they are far more damaging to health than nuclear power, even accounting for the types of accidents that har e occurred. In the United Kingdom, it is estimated that deaths from air pollution from the production of electricity by burning natural gas are 100 to 1,000 times more likely than from nuclear power plants. The effects are even more dramatic compared to coal (Markandy, 2007). By comparison, the TMI, Chernobyl and Fukirshima accidents had meltdowns: released radiation to the atmosphere: contaminated nearby areas with radiation yet did not produce the grim results that were postulated.
Advances in Nuclear Technology
Despite the inherent safety of the current generation of nuclear plants, improvements are in progress to both lower construction costs and increase safety. The latest generation of nuclear power plants are large, like the previous generation,3 and require ten years or more to build. It is estimated that those plants currently under construction in the U.S. will cost S20 billion to complete. While they are even safer than those currently in operation, the cost and tune to build them makes them economically difficult to justify. A comparable gas fired generating plant is one tenth the cost of these plants. Even when the cost of gas is included the combined cycle plant is capable of generating electricity at Vi to 'Л the cost of the latest design nuclear plant (Lazard, 2018).
Since a critical component of the cost is financing of construction, efforts are under way to reduce the time to commercial operation. Currently, the effort to reduce cost and construction time is concentrated on small modular reactors (SMR). such as the one depicted in Figure 2. The design features a self-contained steam system that can be built in a factoiy, eliminating the need for much of the onsite construction work typical of current and previous generation reactors. While the power output of such reactors is less than 1/3 that of the current generation of nuclear reactors, they can be combined into a multi-modular plant with 2, 3, 4 or more modules, decreasing operating cost. Then small physical size would allow them to be installed underground, making them less vulnerable to severe weather events and helping contain 5 typically for the latest generation III+ reactors are 1000 MWe to 1200 MWe.
Figure 2. NuScale Power ModuleTM, image provided by NuScale Power, LLC.
Figure 3. Cutaway of the PRISM power block. Showing two reactors and associated systems located underground
(GE-Hitachi Nuclear Energy).
radioactivity' in the event of a severe accident. Since all the major systems are in the module, there are no large diameter pipes that could break, causing loss of cooling, as occurred at TMI. Construction in a factoiy would lower cost, cutting down on construction delays associated with weather. Once installed, a module could begin operation, producing income to pay for the installation of the next and subsequent modules, further reducing costs.
Other reactor concepts are also under consideration. Fast reactors, such as the PRISM design (shown in Figure 3), use liquid metal as the coolant and produce more fuel than they consume, at the same time burning up undesirable fission products, which decreases waste production (Triplett, 2012).
Since the reactor uses liquid metal in a pool as a coolant, the system can be operated at low pressure, virtually eliminating the possibility of a loss-of-coolant accident, reducing the stress on the piping systems and increasing the efficiency. Several countries are developing similar concepts but, so far, these types of reactors have been difficult to operate reliably. Furthermore, such fast reactors, when combined with pryroprocessing, provide the option for closing the fuel cycle and the recycling of the spent nuclear fuel inventory, utilizing the valuable remaining energy content (~ 95%) while reducing the half-lives and heat loads of the remaining byproducts, thereby easing the repository requirements.
Fusion, mentioned earlier, holds promise as a source of energy. Recent advances in operation of prototype facilities have shown significant promise that a reliable operating system is possible. Assuming ITER is operational in 2025, as scheduled, the following table provides timelines developed by various countries for the operation of a commercial size fusion reactor (El-Guebaly, 2017).
However, recent advances in the use of high temperature superconducting magnets and their application in compact fusion devices may shorten this timeline (National Academy, 2019).
Unlike fission reactors, the fusion reactor would produce no long-lived fission products and would have a nearly inexhaustible fuel source that could be obtained from sea water. It is unlikely that a commercial fusion reactor will be designed and constructed in the near future. It is likely that in the next ten years we will see a demonstration fusion reactor akin to the original nuclear fission reactor, CP-1, built by Enrico Fermi and his colleagues.
Table 2. International timelines to a demonstration fusion power plant.
Renewables can and do provide a significant source of low-GHG generated electricity. These sources must be supplemented by some form of dispatchable electric source lacking improvements in batteiy technology. Currently, the dominant sources of dispatchable electricity are coal, gas, and nuclear. The former two emit large quantities of GHG, offsetting some of the benefits of renewables. Nuclear is constrained by public perceptions of lack of safety and cost of construction. New designs that may help reduce costs and enhance safety are in the works. Despite these drawbacks, nuclear must be in the mix if GHG production is to be reduced over the long term.
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