A French-led consortium has been selected to build a new protective encasement for Ukraine’s leaking nuclear reactor at  the site of the world’s worst nuclear accident.

Ukraine officials say the European Bank for Reconstruction and Development has chosen a bid from the consortium Novarka to build the encasement for the plant’s number-four reactor. Novarka includes French, German and Ukrainian firms.

A concrete sarcophagus built immediately after the accident still holds 200 tons of dangerous radioactive fuel, and experts say the protective casing is deteriorating.

The Chernobyl reactor caught fire and exploded in 1986, sending a radioactive cloud across large parts of Europe.

The death toll from the blast remains hotly debated. Soviet authorities said 32 people died as a result of the accident. Thousands of other have been diagnosed with thyroid cancer.

Chernobyl’s last functioning reactor was closed in 2000.

The European Bank is contributing nearly $500 million to the project, which is expected to take at least three years to complete.

The World Health Organization estimates that more than 9,000 people worldwide will eventually die from Chernobyl-related cancers. But the environmental group Greenpeace says the death toll could exceed 90,000.

Some information for this report was provided by AP and Reuters.