United States Nuclear Regulatory Commission - Protecting People and the Environment
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Accident Tolerant Fuel

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The first lead test assembly containing ATF rods being loaded in a U.S. commercial power reactor at Southern Nuclear's Edwin I. Hatch Nuclear Plant in Baxley, GA, in February 2018 (photo courtesy of Southern Nuclear)

The first lead test assembly containing ATF rods being loaded in a U.S. commercial power reactor at Southern Nuclear's Edwin I. Hatch Nuclear Plant in Baxley, GA, in February 2018 (photo courtesy of Southern Nuclear).

Accident tolerant fuel, or ATF, is a set of new technologies that have the potential to enhance safety at U.S. nuclear power plants by offering better performance during normal operation, transient conditions, and accident scenarios. The fuel in use today at U.S. nuclear reactors consists of uranium dioxide fuel pellets encased in metallic cladding made of zirconium-based alloys. U.S. nuclear fuel vendors, through partnerships with the U.S. Department of Energy (DOE), are pursuing a range of new concepts, both near-term (deployment by the mid-2020s) and longer-term. Near-term concepts have relatively small departures from today's nuclear fuel designs. These departures include (1) specially designed additives to standard fuel pellets intended to improve various properties and performance and (2) robust coatings applied to the outside of standard claddings intended to reduce corrosion, increase wear resistance, and reduce the production of hydrogen under high-temperature (accident) conditions. Additionally, vendors are pursuing a steel cladding with improved corrosion and hydrogen production characteristics.

In the longer term, the NRC is preparing to receive and review applications for ATF concepts that use new fuel pellet materials that may operate at lower temperatures than current uranium dioxide fuel pellets and that use ceramic silicon carbide cladding, which offers significantly improved performance under high-temperature conditions. In the years ahead, the agency also anticipates receiving for review solid-metallic-fuel ATF concepts, which may offer lower operating temperatures and decreased consequences of cladding breaches.

To varying degrees, each of these ATF designs is expected to offer power plant owners more flexibility in how they operate their plants and to provide more robust performance during normal operations as well as under potential accident conditions. Most notably, ATF designs may enhance the ability to mitigate accidents because of the additional time available to plant operators before the onset of potential fuel-damaging conditions. ATF designs may also reduce the amount of high-level waste produced by operating reactors through the extended operation of fuel assemblies in the reactor core.

Licensing Accident Tolerant Fuel

Whilte the NRC can license these new fuels under the current regulatory structure, the staff is taking steps to make agency processes more efficient and effective to enable timely licensing. The NRC has developed a project plan to prepare for both near-term and longer-term ATF designs that addresses the complete fuel cycle, including consideration of fuel fabrication, fresh fuel transport, in-reactor requirements, and spent fuel storage and transportation. The plan also acknowledges consideration for operational flexibilities that licensees may seek based upon the additional safety margin provided by ATF designs. Throughout the development of the plan, the staff had extensive engagement with agency stakeholders, including licensees, nuclear fuel vendors, industry groups, nongovernmental organizations, and the NRC's international counterparts.

The plan outlines a new regulatory approach to fuel licensing, in which the NRC seeks engagement with ATF applicants much earlier in the research and development phase than is typical. Data sharing and close engagement with the applicant during the research and development phase should facilitate efficiency in the later licensing phases. This early engagement is designed to identify potential safety issues as soon as possible so that they can be addressed and so that the staff’s overall safety conclusions can be reached within the planned licensing timeframe. The NRC will also refine its regulatory infrastructure in parallel with the industry's research and development efforts. The staff will refine the regulatory infrastructure with significant communication with NRC stakeholders so that transparency is maintained and regulatory expectations are clearly communicated to the applicant as early as possible in the process.

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Coordination with the U.S. Department of Energy

DOE has been a key stakeholder stakeholders throughout these preparations. The staff is monitoring DOE's efforts to advance the technical basis for ATF, both experimentally and computationally. The staff has added ATF-specific addenda to the NRC’s memorandum of understanding with DOE, which allows the staff to engage with DOE on planned testing of ATF designs and to develop and validate the appropriate data required to model ATF. Early access to these experimental data and analyses will allow the NRC to be better prepared for licensing ATF concepts when they are submitted for review.

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Page Last Reviewed/Updated Thursday, February 28, 2019