Some structural engineers believe that the Chernobyl sarcophagus is very close to collapsing now. It could happen before the end of the year. When the original construction of the sarcophagus was hurriedly begun in May 1986, it was called "the shelter." Even the name was a result of the hurried design and lack of thorough planning.
If a collapse occurs, a dangerous radioactive dust cloud will be kicked up into the atmosphere and could spread downwind for 100 kilometers. The intensity of the radioactivity from airborne particulates could be 1000 times greater on a moderately windy day since heavier particles, and more particles can be carried farther.
There is also a chance that the uranium fuel and the numerous isotopes produced after the original explosion could go critical again. This would happen if there was a re-arrangement of the uranium fuel and the other radioisotopes brought about by a collapse and shifting debris. A favorable condition for a new nuclear chain reaction could happen suddenly.
There are some large holes in the roof and walls are fractured. Furthermore, rainwater which has already pooled amongst the debris could be redistributed and act as a moderator. (Criticality events occur at Oak Ridge Tennessee in secret waste dumps when it rains heavily. Workers report a blue glow above the ground where the waste is buried when this happens.)
The "shelter" was built under extraordinary conditions with high levels of radioactivity severely limiting the time for the men to work. These exacting time restrictions did not permit adequate inspections of the damaged structure to create a proper design for re-enforcing the walls and roof. As a result, the construction techniques and reliance upon robotic tools resulted in a poorly constructed sarcophagus which was doomed to failure from the start.
Here is a descriptions of some of these failures:
High radioactivity forced workers to use remotely operated tools which hindered the ability to position steel girders. The girders are not welded, riveted or bolted in place. Only friction and gravity hold them in place -like a "Lincoln Log" cabin. Most of the steel shelter is supported by the pre-existing structure. Since that was severely damaged by the explosion, the load-bearing ability of the new walls and roof is also dubious.
One column was installed 180 degrees from its proper orientation so that the girder placed on top of it is not supported properly. Another girder was misaligned so that it rests upon a concrete pouring form instead of the concrete itself. Many girders and columns are tilting, twisting or bowing under the strain and from the misalignments. Remarkably, a "cascading wall" is slowly moving away from its intended position for unknown reasons. This is an enormous series of walls which looks like a staircase from the side.
Parts of the sarcophagus had to be constructed on top of mounds of debris. These were was made more stable by pouring crushed rock and concrete; but that is hardly a desirable plan for the shelter's foundation. Many normal engineering codes and inspections were bypassed because there was no practical solution for working in such a highly radioactive environment.
Some areas were so hot that workers could only perform a task for 15 minutes. In some cases, workers spent precious minutes climbing over debris, concrete spills and other hazards just to get into their work area. In fact, some spilled concrete actual ruined one expansion joint by filling in what was supposed to be empty space.
Because Chernobyl was built on sandy soil with additional manmade alterations, a magnitude 5 earthquake will have the same effect as a magnitude 6. The sarcophagus would collapse.
If the engineers are correct, we could see another radiological release from
Chernobyl this year.