A giant arch shielding radioactive waste from the 1986 Chernobyl nuclear disaster began sliding into place Monday with a mission of keeping the site safe for generations to come.

The European Bank for Reconstruction and Development (EBRD) -- the project's main sponsor -- is planning to complete the installation on November 29 at a total cost of 1.5 billion euros ($1.6 billion).

At least 30 people were killed on the site of the accident in Ukraine, at the time a Soviet republic.

The world's worst man-made disaster left thousands dead or dying of radiation poisoning over large swathes of the western part of the former Soviet Union.

Reactor Number 4 exploded on October 26, 1986 during a safety check that went horribly wrong.

The accident remained hidden from the world by the Kremlin authorities for weeks.

"The start of the sliding of the arch over Reactor 4 at the Chernobyl nuclear power plant is the beginning of the end of a 30-year long fight with the consequences of the 1986 accident," Ukraine's Environment Minister Ostap Semerak said.

The ill-fated reactor is currently being protected by a concrete dome that was hastily built by Soviet rescue workers and is in danger of leaking nuclear waste.

The EBRD called the construction and sliding of the arch "one of the most ambitious projects in the history of engineering".