Prospects in a carbon constrained world, an MIT view15 November 2018
The authors of a new MIT study say that unless nuclear energy is meaningfully incorporated into the global mix of low carbon energy technologies, the challenge of climate change will be much more difficult and costly to address. For nuclear energy to take its place as a major low carbon energy source, however, issues of cost and policy need to be addressed.
In the future of nuclear energy in a carbon-constrained world, released by the MIT Energy Initiative (MITEI) in September, the authors analyse the reasons for what they regard as the current global “stall” in building nuclear capacity — which currently accounts for a meagre 5% of global primary energy production — and recommend measures that could be taken to arrest and reverse that trend.
The study group, led by MIT researchers in collaboration with colleagues from Idaho National Laboratory and University of Madison-Wisconsin, presented its findings at events in London, Paris, Brussels, Washington and Tokyo. MIT graduate and undergraduate students and postdocs, as well as faculty from Harvard University and members of various think tanks also contributed to the study as members of the research team.
In the 21st century the world faces the new challenge of drastically reducing emissions of greenhouse gases while simultaneously expanding energy access and economic opportunity to billions of people. The MITEI study examines this challenge in the electricity sector, which has been widely identified as an early candidate for deep decarbonisation. In most regions, serving projected load in 2050 while simultaneously reducing emissions will require a mix of electrical generation assets that is different from the current system. While a variety of low- or zero-carbon technologies can be employed in various combinations, the MIT analysis shows the potential contribution nuclear can make as a dispatchable low-carbon technology. Without that contribution, the cost of achieving deep decarbonisation targets increases significantly (see illustration, p28, left column). The least-cost portfolios include an important share for nuclear, the magnitude of which significantly grows as the cost of nuclear drops (see illustration, right column).
Despite this promise, the prospects for the expansion of nuclear energy remain decidedly dim in many parts of the world.
The fundamental problem is cost. Other generation technologies have become cheaper in recent decades, while new nuclear plants have only become costlier.
This disturbing trend undermines nuclear energy’s potential contribution and increases the cost of achieving deep decarbonisation. The MIT study looks at what is needed to arrest and reverse that trend.
The study has surveyed recent light water reactor construction projects around the world and examined recent advances in cross-cutting technologies that can be applied to nuclear plant construction for a wide range of advanced nuclear plant concepts and designs under development. To address cost concerns, the MITEI study recommends:
• An increased focus on using proven project/construction management practices to increase the probability of success in the execution and delivery of new nuclear power plants.
The recent experience of nuclear construction projects in the United States and Europe has demonstrated repeated failures of construction management practices in terms of their ability to deliver products on time and within budget. Several corrective actions are urgently needed:
– completing greater portions of the detailed design prior to construction;
– using a proven supply chain and skilled workforce;
– incorporating manufacturers and builders into design teams in the early stages of the design process to achieve assurance that plant systems, structures, and components are designed for efficient construction and manufacturing to relevant standards;
–appointing a single primary contract manager with proven expertise in managing multiple independent subcontractors;
– establishing a contracting structure that ensures all contractors have a vested interest in the success of the project; and
– cultivating a flexible regulatory environment that can accommodate small, unanticipated changes in design and construction in a timely fashion.
• A shift away from primarily field construction of cumbersome, highly site-dependent plants to more serial manufacturing of standardised plants.
Opportunities exist to significantly reduce the capital cost and shorten the construction schedule for new nuclear power plants.
First, the deployment of multiple, standardised units, especially at a single site, affords opportunities for considerable learning from the construction of each unit. In the United States and Europe, where productivity at construction sites has been low, the MIT recommends expanded use of factory production to take advantage of the manufacturing sector’s higher productivity when it comes to turning out complex systems, structures, and components. The use of an array of cross-cutting technologies, including modular construction in factories and shipyards, advanced concrete solutions (eg, steel-plate composites, high-strength reinforcement steel, ultra-high performance concrete), seismic isolation technology, and advanced plant layouts (eg, embedment, offshore siting), could have positive impacts on the cost and schedule of new nuclear power plant construction. For less complex systems, structures, and components, or at sites where construction productivity is high (as in Asia), conventional approaches may be the lowest cost option.
The MIT study emphasises the broad applicability of its recommendations across all reactor concepts and designs. Cost- cutting opportunities are pertinent to evolutionary Generation III LWRs, small modular reactors (SMRs), and Generation IV reactors.*
Without design standardisation and innovations in construction approaches, the study authors do not believe the inherent technological features of any of the advanced reactors will produce the level of cost reductions needed to make nuclear electricity competitive with other generation options.
In addition to its high cost, the growth of nuclear energy has been hindered by public concerns about the consequences of severe accidents (such as occurred at Fukushima, Japan in 2011) in traditional Generation II nuclear power plant designs. These concerns have led some countries to renounce nuclear power entirely. To address safety concerns, the MITEI study recommends:
• A shift towards reactor designs that incorporate inherent and passive safety features.
Core materials that have high chemical and physical stability, high heat capacity, negative reactivity feedbacks, and high retention of fission products, together with engineered safety systems that require limited or no emergency AC power and minimal external intervention, are likely to make operations simpler and more tolerant of human errors. Such design evolution has already occurred in some Generation III LWRs and is exhibited in new plants built in China, Russia, and the United States. Passive safety designs can reduce the probability that a severe accident occurs, while also mitigating the offsite consequences in the event an accident does occur. Such designs can also ease the licensing of new plants and accelerate their deployment in developed and developing countries.
The study authors judge that advanced reactors like LWR-based SMRs (eg, NuScale) and mature Generation IV reactor concepts (eg, high temperature gas cooled reactors and sodium cooled fast reactors) also possess such features and are now ready for commercial deployment.
Further, study’s assessment of the US and international regulatory environments suggests that the current regulatory system is flexible enough to accommodate licensing of these advanced reactor designs. But certain modifications to the current regulatory framework could improve the efficiency and efficacy of licensing reviews.
Key actions by policy makers are also needed to capture the benefits of nuclear energy:
- Decarbonisation policies should create a level playing field that allows all low carbon generation technologies to compete on their merits. Investors in nuclear innovation must see the possibility of earning a profit based on selling their products at full value, which should include factors such as the value of reducing carbon dioxide emissions that are external to the market. Policies that foreclose a role for nuclear energy discourage investment in nuclear technology. This may raise the cost of decarbonisation and slow progress toward climate change mitigation goals. Incorporating carbon dioxide emissions costs into the price of electricity can more equitably recognise the value to all climate-friendly energy technologies. Nuclear generators, both existing plants and the new builds, would be among the beneficiaries of a level, competitive playing field.
- Governments should establish reactor sites where companies can deploy prototype reactors for testing and operation oriented to regulatory licensing. Such sites should be open to diverse reactor concepts chosen by the companies that are interested in testing prototypes. The government should provide appropriate supervision and support— including safety protocols, infrastructure, environmental approvals, and fuel cycle services—and should also be directly involved with all testing.
- Governments should establish funding programmes around prototype testing and commercial deployment of advanced reactor designs using four levers: funding to share regulatory licensing costs; funding to share research and development costs; funding for the achievement of specific technical milestones; and funding for production credits to reward successful demonstration of new designs.
* The first commercial nuclear reactors built in the late 1950s and 1960s are classified as Generation I systems. Generation II systems include commercial reactors that were built from 1970 to 1990. Generation III reactors are commercial designs that incorporate evolutionary improvements over Generation II systems. Generation IV is the classification used to describe a set of advanced reactor designs that use non-water coolants and are under development today.