An MIT Energy Initiative Low-Carbon Energy Center
Meeting the world’s ever-increasing demand for energy without adding to the burden of atmospheric carbon will require dramatic changes in the way humans generate and use power. Today, fossil fuel–based power generation and transportation systems are major contributors to the all-time-high levels of atmospheric carbon dioxide (CO2). To address the potentially devastating impacts of climate change, future systems will need to produce very low or even zero carbon emissions—and scale up within a very short time horizon: less than 35 years. Nuclear fission is uniquely positioned to help meet this immense challenge because it has the highest energy content of any power source and its growth potential is not limited by resource availability. Nuclear power can also scale up quickly to fulfill huge demand with zero carbon emissions. As climate experts have stated publicly: “There is no credible path to climate stabilization that does not include a substantial role for nuclear power.1
Fortunately, nuclear fission is already a leading source of zero-carbon energy, providing approximately 12 percent of power generation worldwide (2,600 TWh in 20142) and almost 20 percent of total power (800 TWh in 20143) in the United States. Nuclear fission is particularly valuable in the overall power system because it is a baseload resource—one that provides steady, reliable power generation—thus ensuring a secure supply to critical infrastructure. In developing regions where the rapid expansion of secure baseload is a priority, nuclear fission offers a cost-effective, carbon-free alternative to the expanded use of coal. In developed economies with less demand growth, greater utilization of nuclear power will enable fossil-based generation to be phased out. Thus, nuclear fission offers a highly attractive pathway to meet growing electricity demand without increasing associated carbon emissions. In addition, nuclear power offers an attractive route toward decarbonization of the transportation sector by providing the power and heat necessary to operate electric cars or produce synthetic fuels, including biofuels and hydrogen.
Unfortunately, progress toward realizing the enormous potential of nuclear power has been fitful. The substantial capital costs associated with contemporary reactor designs has meant that very few institutions beyond governments and government-backed corporations have been capable of developing new nuclear power capacity. In spite of the industry’s robust safety record, rare but serious accidents such as that which occurred in Fukushima, Japan, have exacerbated public concerns about the safety of nuclear plants. Furthermore, yet-to-be fully addressed questions regarding the nuclear fuel cycle, in particular the waste and proliferation issues, have engendered reticence about expanding the use of nuclear power. However, options are emerging for overcoming these barriers: innovative reactor designs are addressing cost and safety concerns while progress is being made toward developing more environmentally sustainable and secure fuel cycles.
Now, there is an urgent need for a concerted and coordinated effort to support broad-ranging innovation that can move solutions for nuclear power’s contemporary challenges through the research and development pipeline and into commercial deployment. The MIT Center for Advanced Nuclear Energy Systems (CANES), one of eight Low-Carbon Energy Centers developed by the MIT Energy Initiative (MITEI), will provide the platform necessary to reach this goal.
The Center pairs this innovative research with a dedicated techno-economic and systems analysis program, focused on how best to overcome the challenges involved in expanding nuclear power. An MIT team will conduct technology assessments, economic modeling, and analyses of the regulatory, financial, and political aspects of siting, designing, constructing, operating, and decommissioning nuclear facilities.
To leverage all these capabilities, the Center collaborates with a diverse set of private companies, government entities, and nongovernmental organizations, ensuring that MIT research is aligned with the most pressing real-world needs for decarbonizing both the power sector and the broader energy system. By encouraging extensive industry engagement, the Center will ultimately serve as an integrated solutions platform—supporting cutting-edge basic and applied research with a deep awareness of the practical and market barriers that must be tackled to move technologies from lab to market.
Advanced modeling and simulation of neutronic and thermal-hydraulic behavior promises to provide designers of nuclear plants with high-fidelity quantification of the safety margins, as well as the best ways to improve fuel efficiency and operations. Taking advantage of recent advances in computer science, MIT researchers have developed new methods that dramatically accelerate the solution of the equations describing neutron transport—characterization of the movements made by neutrons in time and space from the moment the first atom of nuclear fuel undergoes fission—as well as fluid flow and heat transfer of the reactor coolant in the core. This work aids in the analysis and optimization of nuclear plants, including the ones already in operation, at a very fundamental level.
Advances in light water reactors (LWRs) materials can help to increase the reliability and decrease the operating costs of the current LWR fleet. Ongoing work at MIT includes studies of hydrogen pick-up and embrittlement mechanisms and its mitigation in zirconium alloys, development of accident-tolerant cladding materials and coatings, surface modifications to control the accumulation of corrosion products (known as ‘crud’) on the cladding surface, use of carbon nanotubes dispersions to strengthen the irradiation resistance of metallic alloys, in-situ measurement of radiation damage, and more.
Fluoride salt-cooled high temperature reactors (FHRs) under investigation at MIT offer a safer, potentially less expensive alternative to standard light water reactors. Since FHRs use a low-pressure coolant that does not boil off, and a robust ceramic fuel form that can withstand very high temperatures without leaking, they greatly reduce the risk of accidents and on-site releases of radioactivity. Made possible by recent advances in natural gas combined-cycle plants, FHRs can provide both baseload electricity and peak electricity via a topping cycle fueled either by natural gas or stored heat with incremental heat-to-electricity efficiencies higher than stand-alone natural gas plants. This makes FHRs an attractive new option for meeting the variable needs of a low-carbon world with improved economics.
Offshore floating nuclear plants promise to be safer, less expensive, and easier to deploy than today’s land-based plants. Currently, building a nuclear plant is a long and expensive process plagued by site concerns such as sourcing water for cooling, and providing for the safety of the neighboring population. The offshore strategy developed at MIT proposes situating reactors in relatively deep water far away from coastal populations, linked only by an underwater power transmission line. Building nuclear plants in shipyards, like deep-sea oil platforms, would make it possible to use greatly streamlined methods of construction—significantly cutting costs. In addition, offshore siting minimizes safety concerns by eliminating risks of earthquakes and tsunamis as accident initiators, access to the essentially infinite ocean heat sink, and ensuring no one resides within the plant’s emergency planning zone.
Low-cost energy storage and energy sink technologies could improve the profitability of both nuclear power plants and those using renewable energy. The intermittency of wind and solar generation creates daily and seasonal periods of low, sometimes even negative, electricity prices that erase the revenues of baseload generators, such as nuclear plants. With the development of low-cost energy storage schemes, energy from nuclear power plants could be stored at times of high renewable capacity and low electricity prices, then recovered to generate electricity at times of low renewable capacity and high electricity prices. This would enable nuclear plants to continue to operate at maximum capacity and remain profitable. The crucial requirement here is a low-cost storage medium, meaning solutions are needed that favor heat storage and high-energy density fuel production vs. electrical energy storage in batteries. Examples of ongoing projects at MIT include heat storage in large stacks of firebricks and underground permeable rock, as well as synthetic fuels and hydrogen production with solid oxide cells.
Strategic nuclear fuel reserves (analogous to strategic petroleum reserves) could create energy security for nuclear power-generating countries, reducing the need for domestic fuel-cycle front-end facilities. Strategic reserves are large stockpiles of nuclear fuel, stored either as low-enriched uranium oxide or as pre-fabricated fuel elements. These fuels are stable for hundreds of years, inexpensive to store, and unlike national fuel-cycle facilities, highly proliferation resistant. MIT researchers are studying the technical and political-economic feasibility of establishing an international mandate for domestic nuclear fuel reserves in mature as well as new-to-nuclear-power countries.
Deep borehole disposal of spent nuclear fuel offers the prospect of permanently sequestering high-level radioactive waste in 4-5 km deep boreholes drilled into low-permeability granitic bedrock, well below surface faults and aquifers, thus greatly reducing the number of radionuclide pathways into the biosphere. MIT research centers on simulation of radionuclide transport within the rock, design of the borehole plug, and development of safe and cost-effective drilling, loading and operation strategies.
A risk-informed, performance-based regulatory framework could facilitate the licensing of reactor designs that deviate significantly from traditional LWRs, thus reducing what is considered a major barrier to the development of advanced nuclear power plants. Work is under way at MIT on new regulations that first identify levels of acceptable risk for abnormal occurrences, and then formulate acceptance criteria that are verifiable with best-estimate-plus-uncertainty (BEPU) calculations. These regulatory innovations will ensure a robust level of safety of the nuclear systems, and accelerate the nuclear innovation cycle, thus promoting private investment in new nuclear technology.
1 CNN.com, November 3, 2013. http://www.cnn.com/2013/11/03/world/nuclear-energy-climate-change-scientists/index.html
2 IEA World Energy Outlook, 2015
3 EIA Electricity Statistics, 2015