Czechia's Temelín extends first unit's operating cycle to 14 months

Operators at the Temelín Nuclear Power Plant have loaded fuel into the reactor of the first unit, which they shut down in early June for a regular two-month outage. After the outage, it will switch to a longer, 14-month operating cycle thanks to a higher share of fresh fuel, which makes up a third of the 163 fuel assemblies. Until now, the first unit had operated for 12 months before an outage, plant spokesperson Marek Sviták said today.

“But we are not yet at our target. We want to get there in several steps, gradually extending the original ten-month operating cycle by two months. We are currently reaching the penultimate step,” said Jan Kruml, director of the Temelín Nuclear Power Plant. The second unit switched to a longer fuel cycle last year and has been operating for 14 months.

The number of fuel assemblies remains the same at 163, but the share of fresh fuel assemblies has risen from approximately a quarter to a third. “The fuel enrichment is also unchanged, but the assemblies contain more absorber, which reduces their reactivity. Combined with the higher number of fresh assemblies, this allows the unit to operate for longer. Put simply, it is like putting seven coal briquettes in a stove instead of five and slightly closing the air vent: they last longer,” Sviták said.

The plant management aims to have the units operate for 16 months, followed by a two-month outage. Both Temelín units should reach this target during the coming year. The switch to longer operating cycles also had to be approved by the State Office for Nuclear Safety.

Longer fuel cycles are part of ČEZ’s program, Safely 32 Tera, which aims not only to increase operational safety and efficiency but also to prepare the conditions for nuclear units in Czechia to operate for 60 years. “Temelín is following Dukovany, which switched to a longer fuel cycle two years ago. In practice, less frequent outages mean less strain on the equipment. At the same time, we are laying the groundwork for increasing output from both nuclear power plants by almost two terawatt-hours of electricity,” added Bohdan Zronek, a member of ČEZ’s board of directors and director of its nuclear energy division.

Eighteen-month fuel campaigns are not unusual either; a number of nuclear power plants around the world have adopted them.

Temelín covers about one-fifth of domestic electricity consumption. Since the start of this year, it has generated 9.1 terawatt-hours of electricity, compared with 14.3 terawatt-hours last year.