Electric power generation is a major source of greenhouse gas (GHG) emissions, primarily carbon dioxide (CO2) from fossil fuel combustion. In the United States, electricity generation is responsible for roughly one third of total GHG emissions (80 percent of which come from coal use).  Globally, electricity generation accounts for more than 27 percent of total CO2 emissions and more than one fifth of total GHG emissions.  Given the magnitude of GHG emissions from the electricity sector, low-carbon electricity generation technologies are crucial for achieving the significant GHG emission reductions necessary to avoid dangerous climate change.
Nuclear power is one option in the portfolio of low-carbon electricity generation technologies, which also includes renewables (e.g., wind, solar, and biomass) and fossil fuels coupled with carbon capture and storage (CCS). Nuclear power emits no GHGs from electric power generation, and its overall lifecycle GHG emissions profile is low and similar to that of solar power.  In addition, nuclear power is already a widely deployed technology and can—like coal-fueled generation—provide reliable baseload electric power.
Currently, nuclear power is by far the largest source of low-carbon electricity in the United States. In 2012, nuclear power provided nearly one fifth of total U.S. electricity, which was more than 50 percent higher than the generation from all renewable sources (including conventional hydropower).  The United States has 100 operating nuclear reactors at 62 plants in 31 states; there are 4 to 6 new units expected to come online before 2020.  Globally, nuclear power generates roughly 13 percent of total electricity. 
In order for nuclear power to significantly expand domestically and globally, the United States and the rest of the world must adopt policies to promote low-carbon technology deployment and adequately address concerns about nuclear power safety, nuclear weapons proliferation, and the long-term handling of spent nuclear fuel.
Current nuclear power technology harnesses the energy released by nuclear fission. Atomic nuclei consist of protons and neutrons held together by a strong energy bond. In nuclear fission, a neutron strikes the nucleus of a very heavy atom and splits it apart into lighter atoms, releasing additional neutrons and energy as well. These neutrons, in turn, can fission other atoms. Under precise, controlled conditions, this nuclear fission process can occur as a continuous chain reaction that releases heat in useful amounts.
Many analyses that look at the lowest-cost options for decarbonizing the electric power sector (e.g., via a GHG emissions pricing policy) project a substantial role for new nuclear power plants in meeting demand for non-emitting electricity generation.
In its 2014 outlook for “business as usual” (i.e., a scenario with no new policies), the U.S. Energy Information Administration (EIA) projects no net increase in nuclear generating capacity from now through 2040.  Over the same period, EIA projects that total electricity demand will grow by 28 percent.
In contrast, EIA also modeled an economy-wide carbon price and projected that such an emission reduction policy would spur the deployment of 53 GW of additional nuclear generating capacity above the “business as usual” case by 2040. 
As one indicator of the significant potential role for nuclear power in global GHG abatement, the International Energy Agency (IEA) estimated that nuclear power could provide 6 percent of total energy-related emission reductions compared to “business as usual” by 2050 (and 19 percent of emission reductions from the power sector).  IEA projected that, in this scenario, nuclear power would increase from about 14 percent of global electricity generation currently to nearly one fourth of total power generation by mid-century.
Nuclear power requires very large upfront capital investments in constructing the power plant (e.g., a new 1 gigawatt nuclear power plant might cost $7 billion including the cost of financing). For nuclear power, the capital cost of the plant constitutes roughly three fourths of the levelized cost of electricity, with fuel and operations and maintenance (O&M) costs making up the remainder of the cost in roughly equal proportions. ,  In contrast, capital costs account for roughly 40 percent of the levelized cost of electricity from a new coal power plant, and fuel costs account for about 80 percent of the levelized cost of electricity from a natural gas power plant.  In short, nuclear plants are relatively expensive to build but relatively inexpensive to operate.
The cost of new U.S. nuclear power plants is uncertain due to a long hiatus in the construction of new nuclear plants in the United States, and cost estimates have been trending upward. In 2010, EIA increased its annually updated estimate of the capital cost of a generic new nuclear power plant by 37 percent, citing a trend of rising costs for capital-intensive power sector projects, higher global commodity prices, and the relative scarcity of engineering and construction firms capable of undertaking such complex projects.  In a 2013 update to this report, the overnight capital costs for new nuclear plants were unchanged. 
During the 1980s and early ‘90s, new nuclear power plants experienced long delays in construction schedules and massive cost overruns, which makes potential lenders see new nuclear power plants as riskier than other power plant investments and thus makes new nuclear plant construction more expensive to finance. Given the capital-intensity of nuclear power, financing is challenging for new plants.
EIA’s latest estimates for the levelized cost of electricity from new power plants using various electricity generation technologies put nuclear power at roughly the same cost as electricity from new coal plants but roughly 60 percent more costly than electricity from new natural gas combined cycle plants.  This cost differential makes new nuclear power plants hard to justify without a policy that changes the relative costs of different types of electricity generation based on GHG emissions.
The once-through nuclear fuel cycle is currently the least costly approach to nuclear power. 
More than 90 percent of U.S. nuclear capacity came online in the 1970s and ‘80s before cost overruns, construction delays, and safety concerns ended this wave of nuclear plant construction. Whereas the build-out of the existing U.S. nuclear fleet saw a large number of companies building a variety of idiosyncratic nuclear plant designs with a regulatory licensing process that allowed for significant delays, a new wave of new nuclear plants in the United States is foreseen to include a small number of firms with nuclear power experience building a limited number of standardized plant designs under a new licensing framework that front-loads much of the regulatory risk.
The Energy Policy Act of 1992 overhauled the nuclear licensing process, which used to require two licenses—one to build the plant and another to operate it. Under the new process the U.S. Nuclear Regulatory Commission (NRC) can: 1) pre-approve a prospective site for a new nuclear plant, 2) certify a new reactor design, and 3) issue a single combined construction and operating license (COL). 
In 2005, Congress enacted new financial incentives (mainly federal loan guarantees) to help spur the first wave of a new generation of nuclear power plants. Subsequently, U.S. electricity providers did begin to pursue new nuclear plants. Currently, COLs have been issued to South Carolina Electric & Gas for Summer (Units 2 and 3) and to Southern Company for Vogtle (Units 3 and 4). There are nine additional license applications under active review by the NRC for up to 14 new reactors, with all of the license applications filed since 2007. 
Nonetheless, the high capital costs of new nuclear plants, the relatively lower cost of new natural gas generation following the domestic “shale gas revolution,” and continuing lack of federal policy to reduce GHG emissions and incentivize low-carbon energy technology all limit enthusiasm for new nuclear projects in the United States. As of April 2013, five new nuclear units are actively under construction. Watts Bar Unit 2 in Tennessee is expected to come online in December 2015.  Additionally, construction is well underway at Vogtle Unit 3 in Georgia and V.C. Summer Unit 2 in South Carolina. ,   The U.S. Department of Energy (DOE) has conditionally awarded a federal loan guarantee to one new nuclear plant (Vogtle) and is negotiating with three other projects.  The process of licensing and building the first few new nuclear plants is expected to take approximately 9-10 years, with 4-6 new units expected to start commercial operation by 2020. ,  
Industry experts consider successful on-time, on-budget completion of this handful of new reactors crucial for creating confidence that new reactor construction can avoid the pitfalls of the past and enabling subsequent nuclear project developers to obtain financing from the private sector without government backing.
Nuclear power also faces potential political and public acceptance hurdles. After decades, the United States still has yet to resolve the issue of long-term handling of spent nuclear fuel. The Obama Administration withdrew the license application for the long-awaited Yucca Mountain geologic repository and appointed a blue-ribbon commission to reassess the options for long-term spent fuel management. The commission delivered its report in January 2012, and it is now up to the Administration and Congress to decide how to proceed.  Presently, the United States is pursuing a once-through nuclear fuel cycle. A fully closed fuel cycle would require not just advanced reprocessing and recycling technology but also the capability to manufacture a new type of reactor fuel from the reprocessing outputs.  According to the nuclear industry, the new generation of reactors necessary for a fully closed fuel cycle is decades away from commercial development. 
In March 2011, a catastrophic earthquake and resultant tsunami struck Japan and led to the failure of reactor and spent fuel storage cooling systems at the Fukushima Daiichi nuclear power station and subsequent damage to the reactors and fuel rods and releases of radioactivity. Global responses to the accident have been mixed. In the immediate aftermath of the disaster, Japan had decided to shut down all of its reactors as well as discontinue a plan to build 14 new nuclear reactors by 2030.  However, Prime Minister Abe plans to enhance safety standards and restart reactors.  German policymakers are pushing ahead  with a plan to shut down all nuclear reactors by 2022, and Switzerland has also decided to not replace its five existing reactors. ,   In the United States, the Nuclear Regulatory Commission has identified several lessons learned from the accident and is implementing safety enhancements in the existing fleet.  The accident is not expected to impact current U.S. nuclear construction activities. Overall, the use of nuclear power is expected to increase  with an increased focus on nuclear safety driven by developing countries, especially China and India.
Worldwide, 67 new reactors are currently under construction in 13 countries. 28 of these reactors are in China, which has only 17 reactors operating now.  ,   Other countries currently building multiple new reactors are Russia, India, South Korea, and the United States.
In the absence of regulation of GHG emissions, new nuclear power is typically more expensive than existing or new conventional fossil fueled electricity generation.
The up-front capital investments required for nuclear power plants make financing difficult for U.S. electric power generators given their relatively small market capitalizations, especially in restructured electricity markets. Many of the existing nuclear plants proved to be far more expensive to build than expected and faced long delays in construction schedules.  Commercial lenders are thus reluctant to finance new nuclear plants on a project finance basis at a cost of capital comparable to other power generation technologies until “first-mover” firms demonstrate that new nuclear plants can be built on time and within budget.
Experts have concluded that geological repositories can safely isolate nuclear waste over the long term; however, so far no country has successfully implemented such an approach for spent nuclear fuel and high-level nuclear waste.  final waste disposal facilities ,  The United States currently has over 60,000 tons of nuclear waste at more than 100 temporary sites (primarily nuclear power plants) around the country, and the fleet of existing nuclear power plants generates approximately 2,000 tons each year.  Moreover, even the proposed fully closed fuel cycle that may be a future option will still necessitate long-term geological waste disposal.
Under the provisions of the 1982 Nuclear Waste Policy Act, the federal government has responsibility for managing spent nuclear fuel produced by commercial reactors. The federal government has been collecting fees from nuclear power generators as part of contracts that originally required DOE to begin taking spent nuclear fuel for long-term disposal in 1998.  In 1987, Congress designated Yucca Mountain in Nevada as the sole candidate for a federal long-term geological repository for nuclear waste. However, the site engendered intense political opposition from Nevadans, and the Obama Administration has terminated the Yucca Mountain nuclear waste repository program.  Given current law, indefinite storage at reactor sites and other existing temporary facilities is the only alternative to Yucca Mountain absent additional congressional action.  Given the challenges encountered in opening a long-term geological repository, DOE has not yet begun taking spent nuclear fuel from nuclear plants and is not expected to do so for several years.
Several states—including California and Wisconsin—have laws that effectively ban the construction of new nuclear plants until a federal long-term waste disposal repository is operating.  Elsewhere, the lack of a solution for long-term spent nuclear fuel management creates uncertainty for new nuclear power plant sponsors. However, the NRC has determined that spent nuclear fuel can be safely stored at reactor sites for 30 years after a reactor shuts down, and NRC has proposed at least 60 years of storage after reactor shut-down as a safe period. 
The industrial resources and supply chains needed to build and operate nuclear plants may present challenges to a significant expansion.  Moreover, the current nuclear workforce is aging and retirements may exceed new entries resulting in a loss of experienced operator and maintenance personnel. 
The global nuclear power industry has experienced four serious nuclear reactor accidents—at Windscale (1952) in the United Kingdom, Three Mile Island (1979) in the United States, Chernobyl (1986) in the former Soviet Union, and Fukushima Daiichi (2011) in Japan—and several fuel cycle facility incidents.  Neither the Windscale nor Chernobyl facility utilized a modern containment structure. Nuclear reactor damage is a potential threat to public health as it can lead to release of radioactivity to the air and groundwater. To date, the United States has had no immediate radiological injuries or deaths among the public attributable to accidents involving commercial nuclear power reactors.  Following the Three Mile Island accident, improvements were made to plant safety equipment, procedures, and training in U.S. reactor operations which significantly increased the safety of the U.S. nuclear fleet.  Moreover, new reactor designs have projected risks—particularly vulnerability to loss-of-coolant accidents—that are one to two orders of magnitude less than those of operating LWRs.  Nonetheless, the recent Japanese nuclear accident has once again focused attention on the safety of existing and planned nuclear reactors. However, it is important to stress that there have been no deaths attributable to radiation exposure from the Fukushima accident to date.
In addition to accidents, intentional attacks on nuclear power plants by terrorists could theoretically lead to nuclear reactor damage. Following the September 11th terrorist attacks, security at nuclear power plants came under increased scrutiny, and new regulations from the NRC increased the level of protection against terrorist attacks.
The nuclear proliferation risk stems principally from the potential for countries to covertly use uranium enrichment or spent nuclear fuel reprocessing plants to generate materials for use in nuclear weapons, and theft of poorly secured nuclear materials could result in transfer to a dangerous state or terrorist group.  In particular, current commercial reprocessing technology generates separated plutonium that is directly usable in nuclear weapons. 
A policy, such as cap and trade (see Climate Change 101: Cap and Trade ), that puts a price on GHG emissions would discourage investments in traditional fossil-fuel use and spur investments in a range of low-carbon energy technologies, including nuclear power.
A policy that required electric utilities to supply increasing percentages of low-carbon electricity (e.g., a clean energy standard ) would likely substantially increase investments in new nuclear power.
Policymakers could rely on performance standards to drive nuclear deployment by enacting new regulations that establish maximum allowable CO2 emission rates for power plants (California, Washington, and Oregon have such standards).  If stringent enough, such standards could lead power generators to turn to nuclear power and other non-emitting technologies.
The Energy Policy Act of 2005 included provisions for loan guarantees, production tax credits, and standby insurance for “first-mover” new nuclear power plants.  Commercial lenders have indicated that the first wave of new nuclear plants built in the United States without assured cost recovery from electricity ratepayers would be difficult or impossible to finance without federal loan guarantees owing to the perceived high risk of such projects in light of the poor track record of constructing the existing U.S. nuclear fleet.  With the current level of federal loan guarantees available for new nuclear power plants, two or three “first-mover” nuclear plants could obtain financing backed by federal loan guarantees and—if they demonstrate success in on-time, within-budget construction and operation—lower the perceived risk of investing in new nuclear power plants and make subsequent plants’ financing easier and less costly. An expanded loan guarantee program could support more “first-mover” nuclear projects. 
In January 2010, President Obama established the Blue Ribbon Commission on America’s Nuclear Future , a step also supported by congressional leaders and the nuclear industry. The commission was tasked with evaluating alternatives and recommending a new plan for managing the back end of the nuclear fuel cycle (i.e., the storage, processing, and disposal of spent nuclear fuel). The commission’s final report was issued in 2012.  Implementation of the commission’s recommendations will likely require congressional action as the only option for long-term waste management under current federal law is Yucca Mountain.
MIT’s 2003 report on nuclear power recommended several avenues for research, including: advanced LWRs and high temperature gas reactors; lab-scale research on reprocessing technologies with the potential for lower cost and greater proliferation resistance; establishment of a large nuclear system analysis, modeling, and simulation project; and a global uranium resource evaluation.  Several other expert reports have also suggested that efforts related to reprocessing focus on R&D rather than deployment, including reports by the Government Accountability Office, the National Academy of Sciences, and the directors of the Department of Energy’s national laboratories. 
The NRC and nuclear plant owners can continue to advance nuclear plant safety via adequate regulation and oversight, continuous improvement based on operating experience, and an emphasis on safety culture. In particular, regulators and the nuclear industry will have to learn from and take steps necessary to minimize the risks exposed by the Japanese nuclear accident.
R&D investments in and international collaboration on technical safeguards—i.e., the technologies used to monitor and protect nuclear materials from proliferation threats domestically and under international agreements—and the inclusion of increased proliferation resistance in next-generation nuclear reactor designs can limit the risk of nuclear proliferation.  The MIT nuclear report and the directors of the national laboratories recommend that nuclear supplier states (e.g., the G-8) offer fuel cycle services to nations developing new nuclear capabilities on attractive terms in order to slow the process of additional nations, especially new users with only a few reactors, building enrichment and reprocessing facilities.  In December 2010, the International Atomic Energy Agency (IAEA) approved the creation of such an international fuel bank, which will be funded in part by the United States. 
The federal government can foster a robust nuclear workforce via increased educational funding for relevant graduate and undergraduate university education and certification programs at community colleges.  Grants for job retraining could also help displaced workers transition into nuclear and other growing energy industries.
DTE Energy 
Duke Energy 
Rio Tinto 
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Massachusetts Institute of Technology (MIT)
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Nuclear Energy Agency (NEA ).
Nuclear Energy Institute (NEI ).
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  Nuclear Energy Agency (NEA), Nuclear Energy Outlook 2008 . About 20 percent of current nuclear plants today use heavy water as a moderator and coolant (mostly in Canada and India), while the United Kingdom has 18 gas-cooled reactors.
  In a BWR, the water heated by the energy released during the nuclear fission chain reaction in the reactor core turns directly into steam to power the turbine-generator (for an explanation of a BWR, see EIA’s Boiling-Water Reactor ). In a PWR, the water passing through the reactor core is kept under pressure so that it does not turn to steam but rather is used to exchange heat with a separate water loop to create steam and power a turbine-generator (an explanation of a PWR, see EIA’s Pressurized-Water Reactor and Reactor Vessel ).
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  NEI, April 2011. NEI reports that this 9-10 year process breaks down as follows: approximately two years to prepare an application to the NRC for a COL, approximately three and a half years for NRC review and approval of the COL, and 4-5 years for construction. NEI expects that subsequent plants might have a licensing and construction timeline of only about six years.
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