This paper targets the reduction of fixed operations and maintenance (O&M) costs for advanced reactor (AR) designs. The ability to achieve such reduction will be severely constrained if the assumptions that underly O&M approaches and practices are not questioned and reexamined, especially in the present day, when changes can be implemented both effectively and efficiently. Reducing AR O&M costs necessitates a paradigm shift that is unrealizable through incremental, technology-focused approaches alone.The present work addresses this challenge by evaluating the impact of moving to shorter design lives for major structures, systems, and components (SSCs), as well as to shorter, more predictable refurbishment cycles, as modeled by the commercial airline industry. This is termed the build-to-replace approach. The present paper briefly overviews this new perspective on AR O&M, and provides a set of multi-objective optimization-based analytical tools to identify the benefits of this type of approach. As a direct example, we analyze a specific build-to-replace scenario by identifying and evaluating cases involving reduced SSC lifetimes and associated replacement/refurbishment schedules, thus enabling an evaluation of the impacts on O&M costs and other lifecycle elements, such as SSC reliability.

Recent years have seen the achievement of important milestones in the harnessing of fusion energy for potential commercial applications. However, even ambitious timelines place the commissioning of a commercial pilot plant at least a decade away. The path to commercialization will involve the development of a commercially viable design, featuring a robust safety and reliability case that (1) comprehensively characterizes system safety, (2) facilitates regulator interactions via industry standard analytical methods, and (3) can build confidence with potential stakeholders. This path benefits from fusion not being burdened with some of the hazards associated with fission (e.g. criticality, decay heat), and therefore lends itself to a "clean slate" approach to design and safety assessment.The Electric Power Research Institute (EPRI) and Vanderbilt University (VU) have demonstrated a technology-neutral safety-in-design (SiD) methodology that incorporates risk and reliability considerations into each stage of the design, thereby incrementally building the safety and reliability case for a technology. The SiD methodology was originally developed for assessing early-stage advanced fission reactors, addressing challenges associated with limited operational experience, unfamiliar systems, and unique radiological, chemical, and other industrial hazards, thus supporting a technology-agnostic, flexible approach.The SiD methodology leverages established qualitative and semi-quantitative process hazard assessment methods, offering a practical means for developing the building blocks for quantitative risk assessment (if needed), and supports efficient early engagement with regulators. EPRI and VU, with fusion community members, utilities, and regulators, are evaluating the application of the SiD methodology to fusion technology.This paper presents an initial outline of a body of knowledge (BoK) that identifies and categorizes papers, reports, and technical standards reflective of academic and industry efforts in topical areas related to fusion safety and reliability. BoK development is a common approach to capture and describe the state of the art in a technical domain; for example, the BoK process has been used to perform the initial organization of the state of the art in areas such as systems engineering, environmental engineering, and project management. Here, BoK development is intended to provide the fusion community with access to a compendium of technical information to draw on during design, safety analysis, and early engagement with regulators and stakeholders.To date, more than 100 documents have been identified to form the BoK for the SiD application to commercial fusion plants. We have presently organized this documentation into seven topical areas: (1) a description of fusion technologies, (2) previous fusion safety analyses, (3) reliability studies, (4) safety analysis insights from nonfusion facilities, (5) fusion regulation and relevant technical guidance, (6) safety, environment, fuel cycle, and decommissioning studies, and (7) commissioning and operation studies. Preliminary engagement with the fusion community indicates that the SiD approach can inform and support fusion technology developers seeking to mature commercially relevant designs and build robust safety and reliability cases for technologies in an environment characterized by evolving regulatory regimes and limited operational experience.

The dominant nuclear reactor technologies that comprise the current global operating fleet were developed and deployed over a relatively short, midtwentieth century, period spanning the 1950s and 60 s. Four of these technologies were deployed at fleet scales and commercially exported. The historical record indicates a remarkably consistent process of phased technology development that enabled the commercialization of designs that would define the global nuclear marketplace, beginning with research and development (R&D) and advancing through test reactors, small and large demonstration reactors, and first commercial-scale units. Following proof-of-principle R&D, historical commercialization lead times (from decision to construction of a demonstration reactor to first commercial launch) ranged from 12 to16 years for these four commercial technologies. Key factors contributing to successful commercialization included durable government support for early R&D and varying degrees of public-private partnering through commercial launch. This partnering included arrangements for technical support, siting, facility ownership, nuclear material provision, and cost sharing. The policy environment was characterized by unambiguous government support; stabile, effective and informed government program management and oversight; and flexibility in the public-private partnership arrangements to promote technology development and demonstration. Government advocacy was structured to support progressively increasing industry independence and self-sufficiency. This experience is documented and analyzed in this paper to provide salient lessons and example program elements for contemporary efforts to stimulate development and commercialization of a new generation of advanced nuclear technologies through collaboration and public-private partnerships.

Increased attention has been focused on the potential role of nuclear energy in future electricity markets and energy systems as stakeholders target rapid and deep decarbonization and reductions in fossil fuel use. This paper examines models of electric sector planning and broader energy systems optimization to understand the prospective roles of nuclear energy and other technologies. In this perspective, we survey modeling challenges in this environment, illustrate opportunities to propagate best practices, and highlight insights from the deep decarbonization literature on the range of visions for nuclear energy's role. Nuclear energy deployment is highest with combinations of stringent emissions policies, nuclear cost reductions, and constraints on the deployment of other technologies, which underscores model dimensions related to these areas. New modeling capabilities are needed to adequately address emerging issues, including representing characteristics and applications of nuclear energy in systems models, and to ensure the relevance of models for policy and planning as deeper decarbonization is explored.

There are diverse views on the role nuclear power might play in a decarbonized energy system, with some vocal viewpoints suggesting nuclear should either have no role or that nuclear should be a key pillar. Here we present a perspective on the role of nuclear power based on our collective experience in modeling nuclear power within the decarbonized U.S. power systems. We summarize the costs of current reactor development projects, and compare their stated costs with the costs that our models indicate is necessary in order to see deployment of new nuclear. We also discuss aspects of new nuclear deployment that are not included in our models but can influence decisions about whether to invest in new nuclear capacity.

This study explores the roles of existing and next-generation nuclear power technologies in a decarbonized U.S. electricity system.Scenario analysis in four state-of-the-art electricity planning models explores the relative competitiveness of nuclear power across a wide range of policy and technology futures.Results from across the four models and scenarios reveal that disparate projections for nuclear power plant retirements are explained by different cost assumptions, and the economic deployment of new nuclear capacity requires a stringent emissions target or significant capital cost reductions.The combination of these drivers could result in substantial expansion of new nuclear power, which is operated more flexibly to complement widespread deployment of variable renewable energy technologies.Increasingly stringent emissions targets drive an evolution in the revenue streams for nuclear power plants and a pronounced increase in the cost point at which new nuclear capacity achieves competitiveness.More work is needed to refine cost projections and noneconomic factors that will influence the deployment of next-generation nuclear technologies.

To support learning/technology transfer from historical nuclear demonstration projects to advanced reactor design, this manuscript: (1) reviews motivation for incorporating historical information into the advanced reactor design process; (2) proposes a methodology to systematically incorporate safety and operability insights derived from operations and maintenance data available for historical nuclear systems into the design of modern systems, drawing from the principles of Safety-in-Design; (3) presents a case study system on which the methodology was applied; and (4) summarizes the insights gained and lessons learned from the case study. The methodology developed to mine insights from historically operated parallels to advanced reactors is based on the principles of functions-based systems engineering and the Systems-Theoretic Accident Model and Process. The system used to test the methodology is a molten salt sampling system, a subsystem within molten salt reactors intended to remove samples of fuel/coolant salt for analysis of safety and operability parameters.

The potential role for advanced nuclear reactors in U.S. markets is highly uncertain and depends on future technologies, markets, and policies. Using a detailed model of power sector investments and operations, this analysis systematically explores potential drivers and barriers to midcentury advanced nuclear reactor commercialization. Model results suggest that extensive deployment of advanced nuclear technologies would likely require a combination of new policies (especially carbon pricing), innovation in technologies to significantly lower capital and financing costs (likely below $4000/kW), and innovation in business models to enable nonelectricity revenue streams. With policies targeting stringent emissions reductions, the presence of technologies like lower-cost advanced nuclear can reduce compliance costs by over 50%. However, without strong policy support and in a market with low-cost renewables and gas, costs of advanced nuclear reactors would have to decrease substantially from current estimates to make them economically competitive by 2050.

As the global community strives to curb carbon emissions from the energy sector, focus has sharpened on the role nuclear energy can play in the effort throughout the 21st century. While the light water reactor fleet provides the nuclear generation backbone for meeting future capacity needs and emission goals, more than half of the world’s nuclear power plants have surpassed 30 years in service.The Electric Power Research Institute (EPRI), in collaboration with research entities around the world, helps turn the world’s carbon neutrality challenges into opportunities. EPRI’s work delivers research to answer key questions about modernization efforts that can provide safe and cost-effective life extensions for long-term operation, increase operational flexibility to support stable power grid dynamics, reduce nuclear power plant operating costs, and the examine the latest reactor technologies for more viable new nuclear power plant construction.

Views on the feasibility and utility of deep borehole disposal (DBD) tend to be highly polarized – many skeptics quickly dismiss the concept while proponents avidly promote the benefits. There is room for a more neutral stance to inform the debate. In an effort to find this middle ground, this paper examines DBD from a strategic industry perspective, considering its potential role in the world of used fuel and high-level radioactive waste (HLW) disposal as a potential technology for (1) niche applications and (2) a confidence building option to complement conventional approaches to managing longlived radioactive wastes. DBD is not a panacea for any and all used fuel and HLW disposal needs, and there are many technical challenges to be overcome for DBD deployment. However, the many challenges are joined by positive attributes that could be realized through a phased DBD demonstration. Given chronic delays of many national repository programs, commercial entities in these countries must continue to manage inventories of used nuclear fuel and HLW without clear disposition paths. In the face of such uncertainty, technology options, like DBD, could offer substantial value to industry. In light of the current lack of alternatives, DBD may warrant further development and demonstration to better define and maximize its potential value.

Evaluation of competing advanced nuclear technologies is useful to inform decisions concerning the prioritization of finite resources available for research, development and demonstration. Advanced nuclear technologies and nuclear fuel cycle (NFC) options offer improvements that are only fully realized when deployed and running at steady-state: however, such NFCs will not be implemented instantaneously. A potential transition from the current U.S. once-through NFC (OTC) to a modified-open NFC (MOC) involving a single recycle of plutonium and use of enriched reprocessed uranium has been modeled for a simplified energy demand scenario. The most limiting modeling constraint is the rate at which reprocessing capacity is brought into operation, which dictates the extent to which fuel can be recycled. This approach is different from many previous dynamic modeling efforts because the reality that reprocessing capacity will not be unlimited is addressed explicitly. Volumes of radioactive waste are estimated and tracked for each operation of the OTC and MOC for waste that can be disposed near the surface of the earth and waste that is assumed to require disposal within a geological repository. The volumes of these categories of waste generated by the MOC were 14% and 25% smaller than from the OTC, respectively, over the 50-year simulation.

T is the seventh and final installment in a series of articles in Health Physics News that provides an overview of nuclear power so that the effect of a resurgence of this energy source on the profession of health physics can be anticipated. The previous six articles (Health Physics News July, September, and November 2008 and January, March, and September 2009) have presented an overview of the different elements of nuclear power generation, including uranium recovery, uranium conversion and isotopic enrichment, fuel fabrication, and nuclear power plant design, construction, operation, and decommissioning. This final article in the series covers the so-called back end of the fuel cycle—the ultimate disposition path for irradiated nuclear fuel. As you will read in this article, the path contains a number of options and no small amount of uncertainty about which options may be selected. As with our previous articles in this series, we are fortunate to have an author, Andrew Sowder, PhD, CHP, who is an expert on the subject matter. In light of the fluidity of our own national policy on used nuclear fuel management, Health Physics News Editor-in-Chief Gen Roessler and I encouraged Sowder to convey his own well-informed views on how the political and sociological challenges associated with the development of a national used nuclear fuel management policy may play out, in addition to providing us with an in-depth understanding of the underlying science and technology of this issue.