A polar crane is a bridge crane that rotates 360 degrees on a circular rail beneath the dome of a nuclear power plant's reactor building. It is used for installing main equipment, for fuel loading and unloading, and for reactor maintenance. The polar crane at Akkuyu Unit 1 has a lifting capacity of about 390–400 tonnes and a total weight of about 500 tonnes.
How does a polar crane work?
An ordinary bridge crane travels back and forth on two straight rails. The reactor building, however, is cylindrical; so the crane's bridge rotates on a circular rail installed in the upper cylindrical section of the building. Together with the trolley moving along the bridge, the crane can reach every point of the central hall. This arrangement also explains the name "polar": motion is defined by an angle of rotation and a distance from the centre, as in polar coordinates.
On the Akkuyu Unit 1 crane, the trolley travels along a 41.5-metre bridge. The system consists of the bridge, main and auxiliary trolleys, hoisting and travel mechanisms, an operator cab with a touchscreen, and control panels.
What does it do in the reactor building?
- Construction and installation: Used to move equipment inside the building and for installation work after the inner containment dome has been closed.
- Fuel operations: Takes part in bringing fresh fuel to the working area of the refuelling machine and in fuel loading and unloading operations.
- Maintenance and inspection: During periodic maintenance it performs tasks such as lifting the reactor upper unit and internals.
Because it will be used throughout the plant's lifetime, the polar crane is in the highest category, safety class 1 (see nuclear safety class).
Dimensions of the polar cranes at Akkuyu
| Feature | Value |
|---|---|
| Lifting capacity | About 390–400 tonnes |
| Total structural weight | About 500 tonnes |
| Bridge weight | 282 tonnes |
| Bridge spans shipped | Two, each 42 m and 92 tonnes |
| Installation elevation | +38.5 m |
| Static load test | With a 487.5-tonne test load |
| Manufacturer | TYAZHMASH (Syzran, Russia) |
How is it shipped and installed?
- Shipment: The Unit 1 crane was dismantled into parts and came from Syzran to the Port of St. Petersburg, and from there by sea to the plant's Eastern Cargo Terminal; unloading from the ship in June 2022 took one day.
- On-site transport: The 42-metre bridge spans were moved from the terminal to the unit area. Transporting a part of this length over long distances by road requires special permits and a detailed route survey; the sea route brings this cargo straight to the plant's pier.
- Pre-assembly: The parts were joined on the ground.
- Lifting: In August 2022 it was placed at the +38.5 m elevation in about four hours with a Liebherr LR 13000 crawler crane. This method, carried out from above before the dome is closed, is known as "open top".
- Testing and commissioning: The main hoisting mechanism was subjected to a static test with a 487.5-tonne test load; the crane was commissioned in October 2023.
At Unit 2, the 282-tonne bridge was placed at the same elevation in March 2026; next, the safety system tanks will be lowered using the open top method and the inner containment dome will be closed. How lifts are planned is explained in the entries crane lifting plan and heavy lifting at nuclear power plants.
Why is it a key point in the installation sequence?
The inner dome cannot be closed until the polar crane is in place, and once the dome is closed, large equipment can no longer enter the building from above. This is why having the crane parts on site on time is on the critical path of the installation schedule. During operation, the reactor upper unit and internals are lifted with this crane; how the vessel itself was brought to the site is explained in the reactor pressure vessel entry.
How does Voltim Global support you on this?
Large parts such as the polar crane come by ship from Russia directly to the plant's pier. Voltim Global, for its part, carries cargo reaching the same project by truck as part of nuclear project transport; of the more than 450 shipments made since March 2024, most used the Tuapse–Taşucu RoRo line, and some went by road via Upper Lars–Georgia and via Iran.