Temelín Loads First US Fuel as Czechia Diversifies From Russian Supply

Czechia is changing what powers one of its largest electricity sources. The Temelín nuclear plant will load its first batch of Westinghouse fuel during the ongoing shutdown of its first reactor, according to Expats.cz. The American assemblies will replace 66 of the 163 fuel assemblies in the reactor, which until now has run on fuel from Russia's TVEL.

The move is the visible end of a long process. Operator ČEZ launched a tender for new Temelín fuel suppliers in 2018 and signed contracts with both Westinghouse and France's Framatome. The Czech nuclear safety regulator, SÚJB, approved the Westinghouse fuel in August after eight years of analysis and testing, including trial assemblies placed inside a Temelín reactor between 2019 and 2022. The first Westinghouse assemblies for this transition arrived last year from the company's plant in Västerås, Sweden, and were inspected and tested before use.

Framatome's fuel has not yet received Czech regulatory certification. ČEZ chief executive Daniel Beneš said the company ultimately intends to use assemblies from both suppliers at the same time. He told reporters that ČEZ holds strategic fuel reserves for all its units and began working well in advance to avoid depending on a single supplier. Dukovany, the country's other nuclear plant, is preparing to introduce Westinghouse fuel as well; its first assemblies have arrived, but use depends on completing testing and licensing.

Finance Minister Alena Schillerová described the diversification as a measure to strengthen Czech energy security as the country prepares to build new reactors and extend the lives of existing plants.

The fuel change coincides with a second shift in how the reactor is run. Temelín's first unit will adopt an 18-month operating and refuelling cycle, roughly 16 months of operation followed by a two-month shutdown. The second reactor already runs on the extended schedule, and the first is expected to follow when its current outage ends in late November. Dukovany has used a 16-month cycle since 2024. ČEZ says longer intervals between shutdowns reduce stress on equipment while raising average output. Beneš said the longer cycles could lift combined production from ČEZ's nuclear plants from around 30 terawatt-hours to nearly 33, worth billions of crowns in additional value.

Further investment is under way. Temelín is preparing to replace the transformers that supply electricity for the plant's own operations. The equipment is being manufactured and will be installed over the next two years in an investment worth hundreds of millions of crowns. The work is part of preparations for potentially operating Temelín's reactors for 80 years, through 2080 and 2082.

For a country that relies on nuclear power for a large share of its low-carbon electricity, the combination matters. A second fuel source reduces the risk that a single supplier, or a single political relationship, can interrupt generation, while longer cycles squeeze more electricity from the same reactors.

Why it matters

Energy security is a sustainability issue before it is a political one. A grid that cannot be starved by a single supplier can keep delivering reliable, low-carbon power through a transition. Temelín shows how diversification is built over years of testing and regulatory approval, not announced in a day.