Computer simulated image of the construction of the New Safe Confinement.
Image: Novarka
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CHERNOBYL, Ukraine—Imagine a metal arch taller than the Statue of Liberty. Now picture it sliding a distance of roughly three football fields, making it the largest movable structure ever . Under this steel rainbow engineers are planning to entomb the site of the worst nuclear accident in history, the destroyed reactor at the Chernobyl power plant, using robotic cranes to dismantle the ruins and keep its deadly remains from poisoning the rest of the planet.
After reactor No. 4 exploded at Chernobyl in 1986 due to errors in both design and operation it sent plumes of radioactive dust as far away as Japan and the U.S. To contain the fallout, the Soviet Union constructed a metal and concrete structure commonly known as the sarcophagus over the wreckage.
"It was really quite a remarkable feat, but after 25 years, it's in danger of collapse," civil and environmental engineer Eric Schmieman of Battelle Memorial Institute explains in an interview in Kiev.
The sarcophagus, technically known as the Shelter Object, was made of more than 7,000 metric tons of metal and 400,000 cubic meters of concrete. It was erected as quickly as possible to limit worker exposure to radiation, and was never meant to last forever. In many ways it was designed "like a house of cards," Schmieman says, with pieces of metal essentially leaning against each other and hooked together. "There are no welded joints or bolted joints—it wouldn't take much of a seismic event to knock it down."
At the same time, when the sarcophagus was completed, "there were over 1,000 square meters of openings in the roof where joints didn't match up," Schmieman says. These holes allowed water in, resulting in corrosion that is hastening the structure's decline. Since then, workers have patched many of these holes, but 100 square meters of gaps remain. To help keep radioactive matter from leaking , a dust- suppression system inside relies on sprinklers that periodically spray a watery solution to prevent it from becoming airborne.
Now, to safely enclose the ailing sarcophagus, the French consortium Novarka is working on a replacement: the New Safe Confinement, a steel structure 110 meters high at its tallest point, 164 meters wide, spanning across 257 meters and weighing more than 29,000 metric tons. In comparison, the Statue of Liberty from the ground to the tip of its torch is about 93 meters high, says Schmieman, who helped lead New Safe Confinement's conceptual design .
Because the destroyed reactor is still highly radioactive, to protect workers, the arch will not be constructed over the sarcophagus. R ather, it will be assembled nearby from prefabricated segments each about 25 meters high and weighing an average of 300 metric tons. Once complete, hydraulic jacks will then slide the arch approximately 300 meters on Teflon bearings during the course of a week to enclose the sarcophagus. Walls on either side of the structure, making it resemble an aircraft hangar, will help isolate debris. "All told, it has a design life of 100 years," Schmieman says.
Inside the structure, three robotic cranes capable of lifting up to 50 metric tons each will be equipped with tools to help dismantle the sarcophagus, using drills, manipulator arms and concrete crushers, along with vacuum cleaners that can suck up to 10 metric tons of dust. The cranes will also employ radioactivity monitors as well as cameras to help remotely operate the tools . Once the sarcophagus and its contents are dismantled , it remains to be seen where the most radioactive material will be buried, but there are facilities to store the less radioactive remains.
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16 Comments
Add CommentWhy can't the Japanese pump some kind of radioactivity absorbing and heat resistant material on those leaking reactors instead of sea-water, which evaporates and contaminates the environment? After they contain it, they can clean up the environment with radioactivity eating bacteria.
Reply | Report Abuse | Link to thisSea water is being used as a coolant. A material that resists heat is the opposite of what they need.
Reply | Report Abuse | Link to this@ gesimsek: Radioactivity doesn't work the way you think. It's not a simple matter of "a thing just eats it and poops out rainbows".
Reply | Report Abuse | Link to this@ fortyseven: You're thinking of wrapping a NUCLEAR REACTOR in insulation? Like the way a stick of dynamite is wrapped in paper? Like the way that most explosions are the sudden release of a large store of energy like maybe the build-up of heat and pressure of a tightly sealed up and insulated nuclear reactor?
It might just work you know ... I suggest you build one and try. Let me know how it turned out.
Just to iterate over the points made above.
Reply | Report Abuse | Link to this1. No know materials can be used to absorb radioactivity of such high levels.
2. Yes, pumping seawater might be a little bad but the requirement is to cool the reactor down till a permanent solution can be put in place ie replace the damaged cooling systems.
3. Insulating the reactor, as stated above, is basically equivalent to creating a very powerful atomic bomb. The amount of nuclear fuel is just too much to go wrong with.
No, my reply to gesimsek is saying that insulation is "the opposite of what they need".
Reply | Report Abuse | Link to this... I suggest you learn to read. Let me know how it turns out.
It should just be sealed...make it a pyramid...something that will last for thousands of years....
Reply | Report Abuse | Link to thisI was thinking some kind of liquid material(graphyt?) that absorbs the flying neutrons and stops the chain reaction. I don't think water can do this. The idea should be to stop the radioctivity mechanism instead of just cooling.
Reply | Report Abuse | Link to this1) Insulated or not, the fissile material in the reactor could not reach critical mass. Therefore it could not trigger any sort of explosive atomic reaction. When they mention "criticality" in regards to the reactor that is a term specific to nuclear power plants at which point the reaction becomes self sustaining. However, nuclear is neither densely packed enough, nor high enough grade to cause an instant, explosive chain reaction. The types of explosions which might occur in a nuclear plant are generally steam explosions (reactors operate at high pressure, water boils at higher temperatures under pressure, therefore if pressure is lost rapidly... boom!) or hydrogen explosions.
Reply | Report Abuse | Link to this2)Graphite would be a horrible idea. Chernobyl exploded so violently, and spewed radioactivity so far, because it had graphite components. When the steam and hydrogen blew open the reactor, the super-heated graphite came in contact with the air and exploded as well, bringing radioactive particles with it. Given that Fukushima is crippled, overheating, and suffering from hydrogen explosions, graphite is the LAST thing they want anywhere near those reactors.
3)The sea water is being mixed with boric acid, which contains boron. Boron absorbs neutrons and helps slow down the nuclear reaction, thus indirectly reducing the heat being generated. The sea water absorbs heat, and then carries it away as more cool water is pumped into the chamber. This was done out of desperation, as there was no other readily available source of water other than the ocean. Most modern reactors are cooled by purified water. Water is a fantastic substance for cooling. So, their use of seawater is not puzzling in the slightest. It was the best thing they had available.
I know that I am just a mechanic but wow, you guys are pretty rough on each other. First, EffKay, get a life other than bullying people on-line that are just asking questions. fortyseven, when EffKay learns how to read and says "I'm sorry" let me know how it turns out. heehee :0)
Reply | Report Abuse | Link to thisAs an American I like to think that we are the best and the brightest but as a human I know that there are smart people all over the world. I am also certain that they have people in Japan that are way smarter than any of us here making these comments working on this disaster.
It's easy to sit in our warm houses and critque how things are being done but at least Japan has heros that are risking their lives to save others, working hard in conditions that most of us can not even imagine. They did not sit and wait for our help.
I Know that they are running temporary power to the water pumps for cooling but, again, as a mechanic, wondering if thoses pump may have beem damaged would it may be a better choice to set diesel pumps outside of the effected area and pipe the sea water in through temporary set-up of pvc pipe?
Thank you for your excellent explanation.
Reply | Report Abuse | Link to thisWhile I find the engineering project to cover the Chernobyl nuke fascinating, I must ask, what other source of energy would require such remediation work, and expense, as a critically damaged nuclear power facility?
Reply | Report Abuse | Link to thisShould nuke plant designers now start installing tracks on each side of a facility to accomidate a moveable structure as a pro-active precaution. Should not all existing facilities be required to install the roads/tracks now (it could not be that expensive compared to trying to do it safely later)? And forget the interior cranes for dismantling the nuke--make them strong enough to be concrete fillable and safe for 1000 years.
And most important, as they going to be selling advertising space on the sides and top of a structure that will be a fly over attraction for airliners going east and west, north and south? General Electric would certainly be a potential customer. Or the ignorant US politicians who still are pushing nuclear (Obomba) could have their campaign signs painted on the structure. Why waste such an opportunity, after all, nuclear power is so safe that there will never be such a containment structure needed again, will there? Fukushima you say? No, they'll get that under control--we hope.
It isn't the largest movable structure. It is only 29,000 tons. The oil rig Troll A weighs 655,000 tons.
Reply | Report Abuse | Link to thisBtw, did you know that Chernobyl continued operating for 15 years after the accident? Workers were going in and out of the plant everyday for 15 years while the world was panicking over radiation.
The operator who was just several feet from the reactor when it blew up is alive and well. The engineer who crawled underneath the blown reactor while radioactive liquid was dripping is also alive and well. They are telling their story to National Geographic over 20 years after the accident.
Today workers regularly go inside the sarcophagus to monitor radiation level. The place is open to tourists.
Did you know one of the guys who filmed the response to the Chernobyl meltdown had to be buried in a lead-lined coffin because he was so radioactive? Did you know the death toll estimates of around 5,000 from this accident have come under extreme scrutiny ever since they were released and the science is settling on around 100,000 premature deaths from Chernobyl? I thought you'd like to know just so you get a more complete version of the story.
Reply | Report Abuse | Link to thisYour version of the story is what media and environmental activists had been playing all along to scare the general public. The story gathered by the National Geographic documentary is a first-hand account of people who actually witnessed the Chernobyl accident.
Reply | Report Abuse | Link to thisThe numbers you are citing are not actual body count but extremely pessimistic estimates of doomsayers that are not verified statistically. The death toll that can be directly attributed to the accident is around 250 from 1986 to 1996. That seems a lot but actually you are more likely to get struck by lightning than die of radiation from the worst nuclear accident.
Anybody could be buried in a lead coffin especially if the relatives were scared to death. How much was the radiation? Did it exceed 20 rem/hr?
Read this version of the story "Lessons of Chernobyl" from Jaworowski of Central Laboratory for Radiological Protection and Chairman of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)
Reply | Report Abuse | Link to thishttp://www.world-nuclear.org/info/chernobyl/health_impacts.html
I think Mr Zbigniew Jaworowski's credibility is not great with the scientific community. He is a contrarian. He seems to believe that low doses of radiation are actually good for you. He bags LNT without giving reasons why other than referring to "a vast sea of data".
Reply | Report Abuse | Link to thisOne of the most telling factors for me is the dramatic decline in the life expectancy of people living in Belarus. While there is no direct causal link that I can point to. It does show a significant decline in health in the most contaminated county.
These cerry picked pro-nuclear industry reports are very dismisive of this factor.