Long-overdue construction of the replacement for the confinement shelter over the ruins of the Chernobyl nuclear power plant’s contaminated unit is being launched on Thursday in Ukraine.

The New Safe Confinement is a 108-meter tall sliding arch structure, which will cover the existing sarcophagus, which had been hastily built as a temporary measure after the nuclear disaster in 1986.

Unlike the old shelter, it will not be supported by the remaining beams of the reactor. It will also be fitted with modern instruments to control the environment in the damaged unit. It will also have necessary equipment to dismantle the old sarcophagus and safely store it, once the new one is in place. It is designed to hold radioactive debris in check for at least 100 years.

Replacement of the shelter is a necessary measure, because the current one is not completely safe. In case of emergency, like an earthquake or a particularly powerful storm, the old reactor may collapse along with the protective cover, releasing contaminated dust and ashes into the atmosphere.

Work on the new confinement started back in 1992, and the initial plan was to have it finished by 2005, but the date was postponed several times. The US$1.4 billion-valued project is expected to take five years of construction work.

President Yanukovich announced on Thursday that the year 2011 will be declared the Year of Solution of Chernobyl Problems in Ukraine.

“Kiev will host an international conference under a UN aegis, dedicated to the 25th anniversary of the Chernobyl disaster,” he said, after meeting with the United Nations Secretary General Ban Ki-moon in New York.

The explosion at the Chernobyl power plant is the world’s worst nuclear accident. It forced the evacuation of tens of thousands of people. Hundreds of plant workers, rescuers and local residents suffered from radiation exposure, and the environmental damage was widespread.

However, evidence suggests that the surrounding nature is recovering from the fallout. Earlier this week, a group of scientists, who studied plants in the Chernobyl’s contaminated zone, reported in the Environmental Science and Technology journal that local plants had adapted to the high radiation there.

The plants’ genes appear to be quite similar to those of their siblings grown on normal soil, although scientists discovered higher protein levels in the Chernobyl plants. It is possible that the extra proteins act as a radiation shield, the scientists speculate.

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