Accident-tolerant fuel completed its second cycle in a commercial reactor in the United States.

The first batch of the new generation of fuel developed with the aim of increasing resilience to severe accidents has successfully completed its second operating cycle in a commercial nuclear reactor and after inspection it will be reinserted into the Calvert Cliffs Nuclear Power Plant (Calvert Cliffs) for a third, two-year testing cycle

A batch of accident-tolerant fuel (Accident Tolerant Fuel – ATF) from Framatome initially was inserted into Unit 2 of the Calvert Cliffs Nuclear Power Plant (Constellation's Calvert Cliffs) in Maryland in 2021, where it completed the first 24 months of operation. After the first inspection and fuel loading in spring 2023, the batch was reinserted and recently it has successfully completed its second two-year cycle of operation in a pressurized water reactor (PWR). Teams from Framatome and Constellation conducted a detailed inspection of the batch during the refueling outage in spring 2025. The batch will now be inserted for its third 24-month cycle, which is expected to be completed in 2027. After that, it will be transferred to a national laboratory of the U.S. Department of Energy (DOE) for post-irradiation analysis, which is crucial for licensing this new technology.

Accident-tolerant fuel represents a new technology being developed to improve the fuel tolerance in light-water reactors under severe accident conditions – primarily by increasing the melting temperature, while simultaneously improving reactor economy and performance. This fuel, part of Framatome's PROtect E-ATF program supported by DOE, contains 176 fuel rods clad in chromium and uranium pellets enriched with chromium oxide. It is expected that these improvements will provide a better response to changes in the reactor core and reduce corrosion and hydrogen production under high-temperature conditions.

The fuel assembly was produced at Framatome's Richland, Washington facility in accordance with the 2019 contract. Chromium-oxide-enriched pellets, which can be produced in Richland at industrial scale, are already a standard feature of Framatome's fuel design for the ATRIUM 11 boiling-water reactors, and are already used in eight American commercial power plants.

The prototype fuel, developed through Framatome's PROtect program, could represent the first significant upgrade of nuclear fuel and cladding technologies since the 1970s, according to DOE. Frank Goldner, the DOE's ATF program manager, stated that this public-private partnership helps achieve national energy goals by providing key data during commercial operation. In addition to Framatome, GE Vernova and Westinghouse are also testing similar accident-tolerant fuel in commercial reactors across the United States, with the aim of widespread deployment by 2030.