Schools/Education

Chernobyl Sarcophagus – The end or just the beginning?

 
“The next Chernobyl will be Chernobyl itself”
(Russian Scientist Professor Chernosenko)

Following the explosion, a massive concrete ‘sarcophagus’ was constructed around the damaged Number 4 Reactor. This sarcophagus encases the damaged nuclear reactor and was designed to halt the release of further radiation into the atmosphere. However, hastily constructed this structure is now cracking open and leaking out lethal doses of radiation.

Since the accident, Central and Eastern Europe have undergone momentous political changes. The USSR no longer exists. Chernobyl is now the responsibility of the respective governments of each of the affected continues, but the fallout from Chernobyl continues to kill and mar the lives of millions. Despite all the words that have been written about the accident, little has changed for the better. In fact, in many ways the situation is getting worse.

 
An aerial shot of Reactor No. 4 taken soon after the fateful explosion

We aren’t finished with Chernobyl. The scientists admit that the sarcophagus which encases the damaged nuclear reactor is now cracking open and leaking out lethal doses of radiation. In 1988 Soviet scientists announced that the sarcophagus was only designed for lifetime of 20 to 30 years. Holes and fissures in the structure now cover 100 square metres, some of which are large enough to drive a car through. These cracks and holes are further exacerbated by the intense heat inside the reactor, which is still over 200 degrees Celsius. The sarcophagus’s hastily and poorly built concrete walls, which are steadily sinking, act as a lid on the grave of the shattered reactor.

The fact is that only 3% of the original nuclear material was expelled in 1986, leaving behind 216 tons of uranium and plutonium still buried inside the exploded reactor, is a chilling reminder that the explosion was not the end, but rather the beginning.
Scientists now agree that this sarcophagus will eventually collapse, and when it does there will be an even great release of radioactivity than in the initial accident.

Twenty thousand tons of concrete floor is about to collapse into what has been described as a mix of radioactive lava and dust, which resulted from the dropping of tons of sand in the early attempts to put out the fire, formed by the fusion of molten fuel, concrete and dust.

The concrete tomb was meant to last forever, but it began to deteriorate in the first five years. The pillars supporting the building which contains the damaged reactor are in serious danger of bursting. If this is allowed to happen, the consequences could include the crashing of debris right through the concrete sarcophagus; or rubble could lunge into Reactor 3 which is right next door. This could trigger a core meltdown which would send another radioactive plume into the atmosphere; this plume would blow all over Europe and beyond.

There are 740,000 cubic metres of lethally contaminated debris inside the sarcophagus, which is ten times more than was previously thought. Locked inside lies is 30 tons of highly contaminated dust, 16 tons of uranium and plutonium and 200 tons of radioactive lava. The rain pours through causing corrosion, the weight of 3,000 cubic meters of water lodging each year further adds to the possibility of the roof caving in.

The result of the water and dust mixing is a dangerous radioactive ‘soup’. When the building became highly radioactive the engineers were unable to physically screw down the nuts and bolts or apply any direct welding of the Sarcophagus, this work was done by robotics, and unfortunately the result is that the seams of the building are not sealed thus allowing water to enter and radiation to escape on a daily basis. The problem of controlling the water and dust inside has never been resolved. This type of project has never been undertaken before and no one knows for sure if it will be effective enough to contain the radioactivity or what will happen in 100 years times.

It took 17 years to get an agreement to rebuild the crumbling sarcophagus at the cost of $1 billion. Chernobyl’s debris will be radioactive for hundreds of thousands of years and must be treated and buried in shallow graves as an urgent priority. In 1998, finally with the help of the European Bank for Reconstruction and Development, a stabilization programme was completed which included securing the roof beams from collapsing.

In early 2003 engineers moved towards completing plans for what may be the largest moveable structure ever built, a 20,000 ton steel shell to replace the failed sarcophagus. If these plans are successful the construction will be the height of a 35 story building. Inside, robotic cranes and, where possible, live workers will then begin the delicate job of prying apart the wreckage and removing the radioactive materials.
This construction will not be completed until 2011. And then the world will wait. The shelter is designed to keep water out and dust in for approx 100 years, or for as long as it takes the Ukrainian Government to designate a permanent storage facility and dispose of all the radioactive material.

It’s a dangerous task, and with no previous experience of such a project to draw on, this work will have to be carried out in the most toxic environment in the world. Excavation is complicated and slow, as soil is so heavily contaminated and has to be divided into two categories, high level and low level. Disposal of this soil must be carefully managed and deeply buried. There will be other unusual problems to deal with, such as the need to manage the new sarcophagus microclimate. As the structure will be so big it could even rain inside, so a process of using natural air current will have to be devised to keep the moisture levels down.

Knowing that only 3 per cent of the original nuclear material was expelled in 1986, leaving behind 216 tons of uranium and plutonium still buried inside the exploded reactor, is a chilling reminder that the closure wasn’t the end but the beginning. Tall cranes still stand, forbidding, leaning over the shells of Reactors 5 and 6, frozen in time, relics of when time stood still on 26 April 1986.