Written by Dan Moneghan, Technical Leader - Nuclear Design and Fuel Cycle
Advanced nuclear technologies are opening new opportunities for the next generation of nuclear power plants. Advanced reactors (ARs), including small modular reactors (SMRs), non-water-cooled reactors, and microreactors, come in a wide range of designs with unique characteristics and applications, some of which will require developing new materials and fuel cycle infrastructure.
EPRI is supporting the deployment of ARs by leading research efforts for the management of new fuel forms and associated waste. We’re developing technical bases to accelerate fuel cycle readiness, enable the use of advanced fuel designs, and support innovative reactor development.
Accelerating Fuel Cycle Readiness
The nuclear fuel cycle refers to the end-to-end process from sourcing to disposing of nuclear fuel. Today, this entails uranium mining, milling, enrichment, and fuel fabrication before reactor operations, and short-term storage after operations. In some countries, long-term storage, reprocessing, and permanent disposal facilities are also used.
The current fuel cycle supports today’s reactor fleet, which typically uses uranium oxide fuel rods enriched to between 3% and 5% Uranium-235. However, many AR designs plan to use new fuel forms including liquid fuels, higher enrichment levels that will require expanding today’s nuclear fuel cycle capacity, and potentially even alternative fissionable materials.
EPRI is conducting analyses and strategic planning to help lay the groundwork for fuel cycle developments that support the deployment of ARs.
Fuel & Enrichment
Currently, Russia supplies much of the world’s enriched uranium. For a ramp up of AR facilities, many nations including the U.S. are interested in developing alternative fuel supply chains, including domestically.
With market pull for ARs still developing, private companies have been reluctant to invest in expensive fuel enrichment and fabrication facilities without government backing. Strong government policies could provide effective incentives to develop fuel cycle infrastructure for the AR fleet, including for new fuel forms as is happening with the Advanced Reactor Demonstration Program in the United States. We explore this topic further in our Advanced Reactor Roadmap, available here, which classifies fuel availability as a top priority near-term needs.
Fuel cycle infrastructure evolves on long timescales, and simulations can be a helpful way to analyze the costs and benefits of different strategies and investments. We compare different fuel cycle simulation tools in 3002008044 and their applicability to an AR design in 3002010474.
Waste Management
ARs using different fuel types than conventional reactors will require new waste management solutions after operation.
Evaluation of Existing Storage Technology for Irradiated Advanced Reactor Fuel
In the U.S. and several other countries, a credible waste management plan is a prerequisite for an owner-operator to obtain an operating license. We evaluate the viability of current waste disposal solutions and prioritize new R&D needs for four types of AR fuel wastes – ceramic/oxide fuels, metallic fuels, tristructural isotropic (TRISO) fuel, and molten salt fuels
Feasibility of Borehole Co-Location with Advanced Reactors for Onsite Management of Spent Nuclear Fuel
We performed a feasibility study to determine if deep borehole disposal co-located with AR plant sites could be a useful waste disposal solution, with recommendations for future research.
An Economic Analysis of Select Fuel Cycles Using the Steady-State Analysis Model for Advanced Fuel Cycles Schemes (SMAFS)
Fuel reprocessing and recycling could have potential cost savings while reducing waste volumes for ARs. Although many technologies still need to be demonstrated and deployed, we have modeled a cost comparison of once-through, plutonium recycling, and waste recycling fuel cycles.
Enabling the Use of Advanced Fuel Designs
With new fuel forms and reactor designs come new operating challenges. Considerable research went into the development, validation, and qualification of fuel for conventional reactors, and innovative AR fuels still require varying levels of technical backing.
We have just kicked off a project to continue the development of the performance characterization approach to fuel qualification, a proposed technology agnostic and performance-based approach defined in NUREG-CR7299 for the purposes of liquid-fuel molten salt reactors. This work will support the qualification and deployment of liquid-fueled reactors.
Advanced Reactor Materials
Many AR designs will operate under high temperature and in environments challenging for corrosion and radiation. New materials are needed to withstand these challenging operating conditions over long periods of time, and data is needed to support their approval by regulators. We provide an overview of AR materials challenges and a roadmap ahead in 3002023876.
Molten Salt Reactors
Molten salt reactors (MSRs) represent the most diverse class of ARs with respect to fuel forms, neutron spectra, and primary coolant chemistries. We provide a technology brief to different MSR designs in 3002020066.
Many MSR designs use liquid fuels, with uranium or other isotopes dissolved directly in the liquid coolant. Over the course of operation, fission products are produced in the molten salt that affect reactor chemistry, waste management, and performance and need to be taken into account. We modeled a fast-spectrum, liquid-fuel chloride MSR in 3002021038 to analyze long-term operating performance.
MSR designs benefit from historic data from the Molten Salt Reactor Experiment (MSRE) in the 1960s, which studied and tested several aspects of MSR designs in detail. We compiled relevant insights from the MSRE in 3002018340.
High Temperature Gas Reactors
High temperature gas reactors (HTGRs) typically an inert gas such as helium as coolant, along with prismatic or TRISO fuel and a graphite moderator.
A collaborative project between EPRI and the U.S. Department of Energy, HTGR developers, fuel suppliers, Idaho National Laboratory, and other stakeholders developed a topical report on uranium oxycarbide (UCO) TRISO fuels, compiling performance and irradiation data. The U.S. Nuclear Regulatory Commission (NRC) accepted this document as a safety evaluation of TRISO fuels in high temperature reactors, providing a standardized basis for stakeholders to use TRISO fuels in future design certification and plant license applications. The report is available in 3002019978.
We assess remaining materials needs and knowledge gaps for gas-cooled reactors in 3002015815.
Sodium-Cooled Fast Reactors
Sodium-cooled fast reactors (SFRs) have seen the most consistent progress over the past several decades among AR technologies. Our report provides an overview of historical SFR construction and operation and summarizes gaps in SFR technology and materials, available in 3002016949.
Lead-Cooled Fast Reactors
Lead has favorable neutronics properties, and lead-cooled fast reactors (LFRs) can use fuel efficiently, reduce waste production, be economically competitive, and meet stringent standards of safety and proliferation resistance. However, liquid lead and lead alloys can be highly corrosive at high temperatures, especially to the steels typically used as structural materials in nuclear reactors.
We discuss the materials needs, knowledge gaps, and collaboration opportunities to advance LFRs in 3002016950.
Supporting Innovative Reactor Development
The evolution and growth of non-electric markets could create energy needs well-matched to the capabilities of nuclear energy solutions. EPRI is supporting the development of innovative reactor technologies that look beyond the current options.
While the existing nuclear fleet has significant benefits in producing large amounts of baseload electricity with zero carbon emissions, ARs could help lower nuclear energy costs further, decarbonize additional sectors of the energy landscape, and facilitate nuclear waste management.
Our research is supporting ARs to operate and succeed in a changing energy landscape.
Flexibility
Creating more flexible applications of nuclear energy could be key to expanding the usage of ARs.
Types of Flexibility for ARs
In 3002020436, we discuss three types of flexibility that will benefit ARs: operational flexibility, the ability to operate with greater maneuverability and compatibility with variable renewable sources; deployment flexibility, the ability to be successfully deployed under a wider range of external and market conditions; and product flexibility, the ability to generate and sell products other than electricity such as heat, hydrogen, or isotopes. All three types of flexibility can increase competitiveness for ARs and create more opportunities for plant deployment.
Siting Flexibility
The siting process for a new nuclear plant can take over 2 years and involve expensive land purchases. New AR designs are expected to have siting flexibility advantages.
Our Site Selection and Evaluation Criteria for New Nuclear Energy Generation Facilities (Siting Guide) – 2022 Revision provides a streamlined decision making process for site selection. The process aligns the current and historic needs of owner-operators, reactor designers, regulators, and other stakeholders, helping ARs and traditional reactors to choose a site that meets project goals. The Siting Guide is available in 3002023910.
With enhanced safety features, many AR designs plan to define the emergency planning zone (EPZ) at the site boundary, increasing the amount of locations an AR could be sited at. We evaluate the EPZ planning process for SMRs in 3002008037.
One appealing application of some AR designs is to locate on or near retired coal plant sites, saving infrastructure and construction costs while replacing generation capacity with a carbon-free alternative. However, reusing industrialized sites presents additional challenges. We provide a guide for developing nuclear energy facilities in coal plant communities in 3002026517.
EPRI’s Research Supports Advanced Nuclear Designs & Fuel Cycles
Increased capacity for nuclear energy production could be key to helping the world meet national energy, economic, climate, environmental, and security goals. We created our Advanced Reactor Roadmap as a living strategic document that outlines the critical actions necessary for the successful deployment and commercialization of advanced reactors, available in 3002027504.
Efforts to secure supply chains and disposal solutions for AR fuels, develop robust materials for challenging operating conditions, and increase flexibility and project efficiency are crucial for the continued growth and success of nuclear power.
We encourage all current and prospective owner-operators of nuclear plants to become EPRI members. This grants you access to our entire research library, helping your plant succeed.
To help navigate the different resources available to members and how you can make best use of your membership, we provide a guide to EPRI resources in 3002025692.
In addition to consulting our research, members may find even greater benefit by getting in contact with EPRI for coordinated solutions and strategies for specific projects. You can get in touch with us at ant@epri.com.