Aug. 9 (UPI) -- The hastily constructed "sarcophagus" originally built to prevent radiation leaking from the destroyed reactor at the Chernobyl Nuclear Power Station is crumbling and will be torn down within four years, officials said.
SSE Chernobyl NPP, the Ukrainian company that manages the plant, has contracted Ukrbudmontazh to disassemble the dome-like structure that was built around reactor No. 4 after its catastrophic core meltdown on April 26, 1986.
The sarcophagus was expected to last for 30 years, but began to fail in less than half that time, requiring a series of reinforcements in the years that followed the disaster. A stabilization project a decade ago extended its maximum "end-of-life" service deadline to 2023.
Recent studies determined the likelihood of total collapse is "very high."
"This is the next logical step resulting from our work carried out for the last 12 years. It is our future, global scope of activities which must be completed," SSE Chernobyl NPP Director-General Serhil Kalashnyk said.
The firm said dismantling the old sarcophagus will be "extremely complicated" due to the severe risk of nuclear contamination, and due to the fact the shelter is held up solely by the force of gravity.
"In order to complete this dismantling task, the contractor has to simultaneously disassemble the shelter and to reinforce it, as the removal of every element will increase the risk of shelter collapse -- that, in turn, will cause the release of large amounts of radioactive materials," the company said.
The original concrete sarcophagus, which took six months to build in 1986, was never considered a permanent solution. It was constructed as an emergency measure to contain radiation and, due to the extreme danger faced by its builders, was poorly assembled. Plans for a replacement, the New Safe Containment arch, began in 1992.
The 540-foot high steel containment shell was finally completed and placed over the reactor in 2016. Workers who must disassemble the old structure will have to work around the new containment in a carefully choreographed series of maneuvers.
The new shell is expected to last for about 100 years -- at which time another replacement must be introduced. Most scientists project the reactor will be radioactive for several centuries. Full cleanup of the Chernobyl site, which began immediately after the accident, isn't expected to be fully complete until 2065. The final cost of the new containment is more than $2.3 billion.
It's unknown exactly how many deaths were caused by the Chernobyl meltdown. A 2005 United Nations report estimated a total of 4,000 people would die eventually from the effects of the disaster.