Reactor opened and fuel removed during planned outage at Czech Temelín

During a planned outage of the second unit at the Temelín Nuclear Power Plant, technicians opened the reactor and removed the fuel from it. According to plant operators, opening the reactor is one of the most demanding tasks and takes approximately a week. Fuel removal took a further four days, which technicians completed in recent days. With the outage, which is scheduled to last two months, the unit will switch to a longer fuel cycle, plant spokesperson Marek Sviták told reporters today.

Opening the reactor, which involves hundreds of individual tasks, begins with the removal of International Atomic Energy Agency seals. "The main activities include disconnecting more than a hundred in-reactor measurements and control rod drives. Technicians then gradually remove the main components that are part of the reactor pressure vessel," said Petr Měšťan, director of the Temelín Nuclear Power Plant.

Technicians gradually dismantle the electrical distribution block, drives and instrumentation, the upper block and the protective tube block, equipment weighing tens of tonnes. They also had to loosen 54 massive studs securing the reactor lid to the pressure vessel. Each of the special studs is just under two metres long and weighs more than 300 kilograms. "A special machine is used both to loosen and tighten them. It can loosen all 54 studs at once. Even so, loosening the studs takes around ten hours," Měšťan added. Plant operators then place the dismantled components in precisely designated locations.

After opening the reactor, technicians flood the fuel unloading corridor with water. Transferring fuel from the reactor to the adjacent storage pool takes approximately four days. Plant operators plan to reload the fuel at the end of March. In the meantime, they carry out inspections or move special containers holding used fuel to storage on the plant site. "With the reloading of fuel, Temelín's second unit will fully switch to an extended fuel cycle. It will now operate for 16 months between two-month outages, six months longer than a few years ago," said Bohdan Zronek, director of ČEZ's nuclear energy division.

During the outage, plant operators plan to carry out more than 18.000 activities, including 80 investment projects. Around 1000 people, including suppliers, will take part in the work. This is Temelín's first planned outage of the year. A two-month outage of the first unit will begin in mid-October.

Since the start of the year, the Temelín power plant has generated 2,7 terawatt-hours of electricity. ČEZ will invest 3,8 billion Czech koruna in modernising the Temelín Nuclear Power Plant this year. This is 700 million Czech koruna more than last year.