The collapsed northern wall of the reactor building of Chernobyl Reactor 4.
A cross section diagram of the final design of the Sarcophagus.
The Cascade Wall (seen on the left of the diagram above) was one of the most difficult sections of the Sarcophagus to build, but it was one of the most important. It covered the partially collapsed northern wall of the reactor building, as well as the pile of highly radioactive debris left by the explosion. The wall was composed of four stepped tiers, and topped out at 54 meters above the ground.
This was the first part of the Sarcophagus to begin construction. To begin, the men of Sredmesh Unit US-605 installed "Pioneer Walls" (I will make a post on these later) to lessen the gamma radiation at the site. They then filled the space between the Pioneer Walls and the reactor with concrete. On top of this base, they placed huge prefabricated metal wall sections, like the one seen below.
Demag 21 prepares to lift a section of the Cascade Wall into place.
The first tier of the Cascade Wall during installation.
Once the wall sections were all in position, remote controlled concrete pump trucks (seen on the left of the above image) filled the space between the wall and the reactor building, in a similar manner to the area between the Pioneer Walls and the reactor building. This process was repeated until the Cascade Wall was completed.
Crews help to position a section of the third tier of the Cascade Wall before it is lifted into place by crane. These sections weighed more than 120 tons.
Note the white cabin on the crane. These were built similarly to the bathyscaphes used to survey the reactor building during construction of the sarcophagus, with air filters and thick lead sheeting.
The first and second halves of the fourth and final tier of the Cascade Wall, on the left and right respectively.
The men of Sredmash Unit US-605 Shift Four, who installed the fourth tier of the Cascade Wall.
I could not find their names, but I felt compelled to share this photo in their honor.
Without the Cascade Wall, radiation levels would have remained dangerously high and radioactive debris would have been left exposed to the atmosphere. Additionally, it shored up the collapsed northern wall of the reactor building, which had to support some of the weight of the roof section of the Sarcophagus. The men who participated in the project are some of the worst affected amongst the liquidators in terms of sickness.
Men of US-605 fourth shift celebrate the completion of the Cascade Wall with a ceremonial flag raising.
[Image descriptions:
First image: This black and white photo shows the partially destroyed northern wall of the reactor building. Twisted metal and piles of concrete rubble sit on various ledges within the collapsed wall. A network of pipes is visible about three fourths of the way up the wall. The main circulation pumps of the reactor sit partially covered by rubble at the bottom of the wall. Burns cover much of the concrete. An even gravel surface makes up the foreground of the photo, and a large crane is on the right. The striped circular stack of the plant rises in the top left of the image.
Second image: A cutaway diagram of the sarcophagus viewed from the west side of the reactor building. It shows the original structure of the power plant and the plans for the structure of the sarcophagus. From left to right it consists of the four steps of the Cascade Wall, then a slight incline up to the roof section over the reactor hall, then another more gradual slope down to the section covering the turbine hall.
Third image: A black and white photo showing a large crane on the right preparing to lift a large section of metal wall on the ground in front of it. The wall has a small section to help it stand on its own protruding at ninety degrees at its bottom, with angular pipes bracing it against the wall. The crane is lifting it via its hook, which is attached in the shape of an uppercase A. A large metal brace holds the two halves of the lifting section apart above the wall section.
Fourth image: A black and white photo showing the early construction of the cascade wall. The collapsed northern wall sits above the newly placed first section of the cascade wall. The wall is on a raised embankment, below which sit a concrete pump truck sticking its spindly white boom into the wall to add concrete and help build the structure.
Fifth image: The same large crane is lifting another section of the cascade wall just off of the ground. The first and second tiers of the wall can be seen in place in the background of the photo. Nine men, dwarfed by the section of wall they are working on, pull on ropes attached to the wall to angle it correctly for placement on top of the previous sections. The heavy protective cabin of the crane can be seen mounted on the crane chassis, a large white metal box with thick windows to protect the driver from radiation.
Sixth and seventh images: these twin images show the lifting of the two final sections of the cascade wall into place. These sections are both shown in the air on the way to their destination.
Eighth image: A group photo of about forty men in front of the destroyed reactor during the construction of the cascade wall. The wall is only partially finished, but the men are posing in two rows for a photo (crazy!). The men are dressed in dark khaki/deep blue clothes, and white sanitary caps that cover their hair and prevent contaminated. Some of them are also wearing masks or respirators.
Ninth image: this color image shows another gathering of liquidators around a blue concrete pump with a red banner attached to the end of its pump arm. The arm is fully extended about a hundered feet into the air. The group is a lot more informal. The cascade wall is seen fully completed behind the men, but several white and orange concrete pumps still work on other parts of the Sarcophagus. The large yellow crane used to lift the wall sections into place sits idle on the right of the image. Also in this image is the iconic red and white striped chimney of the plant.
