On the evening of Friday, October 16, the Temelín Nuclear Power Plant will disconnect its generating Unit 1 from the power grid. This will mark the start of a scheduled outage, during which, e.g. safety systems and the turbine will be inspected, and some fuel assemblies will be replaced. In total, ČEZ plans to carry out more than 19,000 tasks, for which it has tentatively reserved two months.
Temelín NPP has two outages in plan this year
Operators plan to disconnect the Unit's 1 generator from the transmission grid on Friday evening while the reactor operating at approximately one-third of its capacity. The South Bohemian nuclear power plant is scheduled for two shutdowns this year. "All of our nuclear units have transitioned, or are currently transitioning, to longer fuel cycles. At Temelín, we can therefore expect alternating years with two and one outage, which will naturally affect the annual production. However, nothing changes regarding our long-term goal of supplying an average of 32 terawatt-hours per year," says Bohdan Zronek, a member of the ČEZ Board of Directors and Director of the Nuclear Energy Division.
Inspections of the reactor, turbine, or leak tests of the buildings surrounding the reactor
In addition to the replacement of 66 fuel assemblies, hundreds of other inspections, checks, and upgrades will take place at Unit 1. The plant staff will, for example, will inspect the reactor pressure vessel and move four storage casks into the spent fuel storage facility. One of the reactor coolant pumps and one of the four steam generators will undergo inspections.
In the secondary circuit, technicians will perform rigorous inspections of the turbine and generator, including the pulling out of its rotor. "We have a number of construction and modernization projects planned, such as replacing the fire water tank and continuing the transition to a new control system. At the end of the outage, we will verify the integrity of the containment building surrounding the reactor," Petr Měšťan explained.
In total, approximately 1,000 people will be involved in the outage work, half of whom are employees of contractor firms.
In recent years, the ČEZ Group's nuclear power plants have been gradually transitioning to extended fuel cycles. At Dukovany, a 16-month fuel cycle has been the standard since 2024, with units operating for 15 months between outages, followed by an outage lasting more than a month. Temelín will also complete the transition to a longer, specifically 18-month fuel cycle this year. In its case, this means sixteen months of operation and approximately two months of outage. Unit 2 at the Temelín Nuclear Power Plant is already operating under this schedule, and Unit 1 will transition to the extended fuel cycle at the end of November.. The goal of these changes is to increase total electricity generation and reduce the strain on the equipment thanks to the stability of operating parameters.
Marek Sviták, mluvčí ČEZ, Jaderná elektrárna Temelín
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