Nuclear power—a source of low-carbon electricity—is exposed to increasing risks from climate change. Intensifying storms, droughts, extreme precipitation, wildfires, higher temperatures, and sea-level rise threaten supply disruptions and facility damage. Approximately 64 percent of installed capacity commenced operation between thirty and forty-eight years ago, before climate change was considered in plant design or construction. Globally, 516 million people reside within a fifty mile (80 km) radius of at least one operating nuclear power plant, and 20 million reside within a ten mile (16 km) radius, and could face health and safety risks resulting from an extreme event induced by climate change. Roughly 41 percent of nuclear power plants operate near seacoasts, making them vulnerable to increasing storm intensity and sea-level rise. Inland plants face exposure to other climate risks, such as increasingly severe wildfires and warmer water temperatures. No entity has responsibility for conducting risk assessments that adequately evaluate the climate vulnerabilities of nuclear power and the subsequent threats to international energy security, the environment, and human health. A comprehensive risk assessment by international agencies and the development of national and international standards is necessary to mitigate risks for new and existing plants.
National governments and international organizations have not comprehensively examined and addressed the vulnerabilities of operating nuclear power plants to climate change impacts. The International Atomic Energy Agency (IAEA)—the center for international cooperation related to nuclear technology—has commenced to explore adaptation strategies in 2018 (International Atomic Energy Agency [IAEA] 2018); yet, no comprehensive set of guidelines or standards exists for operators. New events and data demonstrate that climate change has already begun to affect the generation of electricity from nuclear power plants (Linnerud et al. 2011; McCall et al. 2016; Zamuda et al. 2013). In 2018, a heat wave forced the shutdown of four nuclear power plants in France (Patel 2018). Several nuclear power plants across Europe have reduced output to comply with thermal requirements of discharged cooling water. Plants in the United States have been forced to shut down for operational safety during temperature spikes (Eaton 2012). Workers have been evacuated from a California nuclear power plant due to wildfires (O&M Industry News 2014). In the case of extreme weather events and the risk of storm surges, the Fukushima disaster provides an obvious analogy for disruptions to nuclear power along coastlines resulting from inadequate risk management in plant design and operation.
Nation-states have fallen behind in their responsibility to govern nuclear technology and its associated risks in the face of the rapidly emerging threats that climate change poses to nuclear power generation. Thus far, policy debate on nuclear power has mainly focused on nonproliferation, reduction of greenhouse gas emissions, and possible plant retirements (Haratyk 2017; Kopytko and Perkins 2011; Stoett 2003; Walker 2011). Research has uncovered plants operating at a deficit (Haratyk 2017; Roth and Jaramillo 2017) and an aging nuclear fleet that faces retirement or license extension (Haratyk 2017; Jordaan 2018). Meanwhile, little to no coordination exists among and between international agencies and national governments to evaluate and respond to the emerging risks to nuclear power from climate change. Existing nuclear power plants face a suite of potentially catastrophic risks from climate change, including those from more intense storms, droughts, extreme precipitation, higher temperatures, wildfires, and sea-level rise. These risks bring new challenges for existing and future power generation (Macknick et al. 2015; Van Vliet et al. 2016), which in the best case may result in operational inefficiencies (Miara et al. 2017; Van Vliet et al. 2016), cost impacts (Macknick et al. 2015), and shutdowns (Zamuda et al. 2013) and in the worst case result in large-scale disasters causing catastrophic damage to facilities. Climate change thus creates vulnerabilities to nuclear power plants that have implications for energy security, the environment, and human health.
Most plants with currently operating reactors did not incorporate present-day knowledge of climate change in their design process. The majority of the existing nuclear fleet was designed and constructed in the 1970s and 1980s with an anticipated service life of thirty to forty years (IAEA 2015a). As of 2017, 449 nuclear power generators were operating at 192 sites in 31 countries with a total combined capacity of 392 gigawatts (IAEA 2017a). Already, 291 operating generators—64 percent of the installed capacity—are aged between thirty and forty-eight years (IAEA 2017a). Extending the operating life of a plant is a cost-effective, low-carbon option that ensures reliable power supply (IAEA 2015b). Indeed, many national governments aim to extend the life of existing nuclear assets, but approaches to doing so vary and lack international consensus on issues such as risk management and vulnerabilities to climate change (IAEA 2015b).
Although the decision to retire a plant or extend its license lies in the hands of sovereign states, that decision may carry international implications if poorly managed due to compounding risks from climate change, be they slow moving (such as sea-level rise) or sudden onset (such as wildfires). Aging plants may receive license extensions that enable them to operate despite not having been designed to withstand the potential impacts of climate change. Meanwhile, the nuclear fleet continues to grow with sixty reactors, amounting to sixty-one gigawatts of power, under construction in sixteen countries (IAEA 2017a). These plants are being built in countries with different economic and technical capacities, political systems, and agendas. There have been some indications that vulnerability to climate change may become part of design considerations (IAEA 2015b). However, such considerations have yet to be internationally accepted or standardized.
International standards published by the IAEA address nearly every aspect of plant planning, design, construction, licensing, operation, license extension, shutdown, and retirement. International standards regulating design and operation of nuclear plants in the face of climate change, however, do not yet exist. Nuclear safety presently relies on nationally regulated standards and guidance that lack verification and enforcement mechanisms at the international level. States may or may not choose to adhere to international standards, leaving regulation in the hands of national governments. As a result, researchers have advocated for the development of a global governance regime for nuclear safety that includes forward-looking risk management instead of “by accident” reactions to operational incidents (Taebi and Mayer 2017).
The time has come to explicitly integrate the implications of climate vulnerabilities into international standards developed to mitigate risks to operating nuclear power plants around the globe. International agencies responsible for coordinating countries in their management of nuclear technologies, most notably the IAEA, should explicitly note these risks in unified standards. National governments will also need to individually (or, better yet, cooperatively) engage in systematic and comprehensive risk assessment and management. An integrated approach to both research and governance of nuclear power is critical in the face of climate risks.
While the urgency to mitigate and adapt to climate change is heightening (Allen et al. 2018), international nuclear politics is moving away from cooperation. Recent stand-offs between the United States and North Korea, as well as the stated intent of the United States to withdraw from several international nuclear agreements, threaten to undermine the cooperation needed to address the risks from climate change in international nuclear politics. In this article, we identify emerging, policy-relevant threats to nuclear power from climate change that require the development of international governance mechanisms to reduce the risk of a nuclear catastrophe. We conclude with a path forward: challenges and opportunities in cooperation, the development of international standards, and improvements in national regulation.
Potential Climate Impacts to Nuclear Power
Siting Risks for New Plants
Nuclear plants face acute risks, such as heat waves, wildfires, hurricanes, storm surges, and floods, as well as slow-onset risks, such as temperature increases, shoreline erosion, and sea-level rise. Disasters such as Fukushima underscore the vulnerabilities of coastal plants and the need for more comprehensive siting criteria than those used in existing plants, particularly older operations designed in the 1960s. Fukushima-scale consequences are not inconceivable with climate change–related disasters, most notably if seacoast plants face increasing risk of storm surges. Flooding river waters have already forced one nuclear power plant in the United States to shut down (Zamuda et al. 2013). Wildfires forced evacuations of nonessential personnel at the San Onofre Nuclear Generating Station in California in 2014. Such incidents suggest the need for new siting criteria that account for climate change. While adaptation options have recently been published by the IAEA (2018), standards have yet to be developed for plant design, construction, and operation. Such standards require a comprehensive examination of climate risks to the existing and aging fleet but also a forward-looking approach to the design and siting of new plants.
Risks to Plant Operations
Nuclear power plants face operational risks from climate change. These risks could negatively impact costs and total electricity generation by, for example, lowering thermal efficiency, reducing load, and increasing the number of shutdowns. Nuclear power plants use large quantities of water for cooling, and warming or decreasing water supplies can critically impact operational viability and efficiency. Over the past decade, intake water supplies with temperatures too high to discharge to the environment or provide sufficient cooling have contributed to an increased number of shutdowns and reduced output in plants across the United States (Zamuda et al. 2013). In 2003, an extreme heat wave in Europe resulted in shutdowns or output reduction in more than thirty plants (Linnerud et al. 2011). Of weather-related outages, 68 percent are related to warm cooling water (IAEA 2015a; Van Vliet et al. 2016). One study suggests that nuclear power supply may drop by over 2 percent per degree Celsius of warming in selected European countries due to operational impacts alone (Linnerud et al. 2011). Local impacts may prove more severe in underdeveloped electrical grids. Nuclear power plants may also prove vulnerable to drought insofar as plants could exceed their water withdrawal limits (US Department of Energy 2016). A recent report indicates that power producers do not yet systematically include vulnerabilities to climate change in their planning in the United States (Bartos and Chester 2015).
The Fukushima disaster was caused by the combination of an earthquake, a tsunami, and inadequate risk management. While not related to climate change, Fukushima demonstrates the potentially negative impacts on energy security due to unexpected nuclear disasters with lagging risk management (particularly if seacoast plants experience sea-level rise and increasing risk of storm surges). For example, the disruption to electricity generation resulted in acute changes to energy markets not only in Japan but globally (Hayashi and Hughes 2013), demonstrating that such extreme events can have profound international implications. The most prominent global effects on energy markets included spikes in demand and price for liquefied natural gas and other fossil fuels (Hayashi and Hughes 2013).
Public Health Risks
The vulnerabilities of nuclear power to climate change further entail public health risks that can have severe consequences locally, which would add to compounding environmental security risks (Detraz 2011). Evacuating, reducing exposure, and regulating food consumption and distribution can mitigate local public health impacts related to large-scale disasters. Management of extreme weather events should include plans for prompt safety measures as well as plans for managing health risks by including individual and multiple exposure pathways (Hamada and Ogino 2012). Immediately after Fukushima, Japan experienced increased levels of radiation in marine biota through a pathway that could have exposed humans to food contamination. Japan failed to implement restrictions on the distribution and consumption of contaminated food until seven and eleven days, respectively, after Fukushima (Hamada and Ogino 2012). Although global risks associated with Fukushima eventually proved low, later research demonstrated that pathways that extend beyond national borders exist.
In general, plume exposure planning extends approximately ten miles (sixteen kilometers) from nuclear power plants, while food and liquid ingestion planning extends approximately fifty miles (eighty kilometers). To understand the extent of exposure risks, we estimated the populations surrounding each nuclear power plant within standard Emergency Planning Zones (EPZs), as defined by the US Nuclear Regulatory Commission (recognizing that EPZs vary for individual plants in practice). Populations near nuclear power plants located along seacoasts were found to be the most numerous. Our analysis shows that an estimated 516 million people globally reside within a fifty mile radius of a nuclear power plant, and 20 million within a ten mile radius (Figure 1). Risks from climate change, including sea-level rise, are real for these populations and have yet to be robustly examined.
Policy Directions for Managing Emerging Climate Threats
Current approaches to risk management have been criticized for being reactive to accidents (rather than aiming to prevent them) and lacking in verification and enforcement mechanisms at the international level (Taebi and Mayer 2017). Instead of developing a risk management approach after a major accident, relevant agencies—particularly the IAEA—should take preventative action to understand and manage risks from climate change.
States may be reluctant to participate in new international agreements for the same reasons they might be reluctant to strengthen already existing standards (Taebi and Mayer 2017). Tensions in international politics, questions about sovereignty, and industry resistance to new regulation may all undermine cooperation. First, tensions in international politics related to nuclear power are currently increasing with the United States–North Korea standoff, the 2018 US withdrawal from the Joint Comprehensive Plan of Action with Iran, and the stated intention of the United States to withdraw from the landmark Intermediate-Range Nuclear Forces Treaty with Russia. Second, the notion of upholding state sovereignty strongly influences cooperation in international nuclear politics. Sovereignty is the underlying reason for the prominence of national regulation and the lack of verification and enforcement mechanisms at the international level. The Paris Agreement on climate change includes provisions regarding adaptation to climate change, though cooperation remains a voluntary measure (IAEA 2018). The United States, the largest generator of nuclear electricity, has stated intent to withdraw from the Paris Agreement, making the United Nations Framework Convention on Climate Change a more challenging forum to initiate global action on this issue. Finally, nuclear energy is already heavily regulated and faces economic challenges—new regulations and standards are unlikely to be well received. In the absence of industry leadership, states may have to take the helm in assessing and managing risks from climate change.
That said, the climate vulnerabilities of nuclear power carry compelling reasons for international cooperation. The consequences of climate change–related risks can extend far beyond political borders. Questions of achieving energy security through a reliable supply of electricity are inherently international due to cross-border import and export of electricity—mitigation of potential disruptions will require that international discussions of nuclear power squarely address climate vulnerabilities for countries with connected grids. Additionally, the degree to which potential disasters may affect human and environmental health across borders is not comprehensively understood. The IAEA could work with national governments to initiate a thorough review of the risks to nuclear power from climate change. In the absence of cooperative action under the IAEA, the Intergovernmental Panel on Climate Change could be tasked by its member countries to determine the state of science by examining both the climate risks to nuclear power and the present state of adaptation. The World Nuclear Association (WNA), whose members generate 70 percent of nuclear energy, has yet to focus on the issue of climate change impacts. The WNA could contribute to a greater understanding of climate vulnerabilities by convening a working group to participate in comprehensive risk assessments.
International Standards to Address Climate Risks
While climate change poses risks to other types of power generation systems (including hydropower and thermal power plants), the consequences of an extreme event impacting a nuclear power facility can be much greater as compared to other types of systems due to the environmental health and safety risks. Thus it is of global importance to develop and implement standards that specifically protect against the new climate change risks, going beyond existing, conventional safety standards for nuclear power plants.
The IAEA’s mandate is to establish standards in collaboration with specialized agencies and the relevant organs of the United Nations that protect health and safety and minimize danger to life and property. In the case of risks stemming from climate change, the consequences not only include health and safety but also energy security and the environment. We reviewed all major international standards from the IAEA and the WNA governing nuclear power plant design and nuclear waste management to evaluate the degree to which vulnerabilities to climate change inform their development (IAEA 2012, 2017b). Overall, there is little acknowledgment of the risks from climate change. Where climate change–related risks are mentioned, guidance does not appear comprehensive.
Even if the IAEA or WNA develops standards, implementation of those standards with regard to both safety and security will almost certainly be in the hands of sovereign states. Under the guidance of new standards, states generating nuclear electricity can develop new policies, regulations, and standards for plant life management, design standards, siting, operation, and spent fuel management. In mitigating vulnerabilities, national governments will have to work with industry to ensure necessary training, capacity building, and implementation.
New international standards and agreements should be based on sound knowledge of climate change so that governments can ensure a secure energy supply while protecting environmental and human health. International organizations involved with disaster management and nuclear power could expand research and analysis to include a robust risk assessment of the vulnerabilities of nuclear power plants to climate change. Prior extreme events may inform such assessments and subsequent risk mitigation strategies, but any risk analysis must include consideration of the anticipated future impacts of climate change over the service life of the facility. Technical expertise, as well as national systems of disaster management and risk mitigation, varies widely across countries that are developing or already have operating nuclear power plants. National governments can ensure adequate technical expertise with capacity building and training.
If states cooperate in understanding risks through existing international institutions, develop standards for risk management, and implement adequate regulations, risk management can keep pace with rapidly emerging vulnerabilities. While political tensions may inhibit cooperation in the short term, the cross-border implications of the climate vulnerabilities of nuclear power offer a compelling platform for countries to work together through international agencies and ensure reliable and secure power while protecting human health and the environment.
Nuclear power plant data utilized in this analysis are available through the PRIS data set with permissions from the International Atomic Energy Agency. Author contributions: SMJ, AS, and ACH designed the study; SMJ conducted the data analysis; SMJ, AS, ACH, and WK wrote the text. Research assistance funded by Johns Hopkins University was provided by Lisa Jenkins. No other funding was received for this research.