Dutch contractor Mammoet has connected the two halves of a critical containment structure at the disaster-hit Chernobyl nuclear power plant.
The firm worked with the Novarka joint venture – formed of French construction giants Vinci and Bouygues – to fit together the mammoth New Safe Confinement shell.
This structure is now ready to be placed over the existing sarcophagus, which was built as emergency protection in the immediate aftermath of the 1986 accident.
The completed confinement structure will provide a controlled, weatherproof environment for the solid radioactive remains of unit 4 for the next 100 years.
The east arch section, with a span of 260m and weight of 19,000t, was skidded to a waiting area in November 2014 to await completion of the second half of the structure.
In order to move and join the two halves of the arch, Mammoet developed and built a specially designed skidding system using a Teflon surface.
A total of 56 skidshoes, with a minimum capacity of 703t each, were used to move the east arch towards the west arch, which is currently on temporary supports.
The system had to be fully remote controlled from outside the contaminated location, yet there were alignment tolerances of just 3mm. The operation took about six hours.
Novarka is now working on the tightening of approximately 1,000 bolts to connect the two halves of the arch.
The structure will be skidded into its final position, over the original sarcophagus, at the end of next year.