Text/HTML

   Minimize


Field book

   Minimize

 

The New Safe Confinement for Chernobyl (NSC) in Ukraine

 

On behalf of the European consortium Novarka, Jean Lutz SA has been involved in the construction of the New Safe Confinement at Chernobyl.

Our Mission: to provide the instrumentation for the implementation of the piles that support the tracks on which will slide this monumental work.

The challenges of the Chernobyl site
On 26 April 1986, reactor No. 4 of the Tchnernobyl nuclear plant on the borders of Ukraine and Belarus, explodes.

600,000 liquidators follow one another in haste to choke the heart of the fusion reactor. They hastily built a shelter made ​​of 7,300 tons of steel architecture and 400,000 cubic meters of concrete, but the structure is cracking in the 1990s, and threatens to let go of radioactive materials.

 

In 2007, the work of designing and building a new shelter is entrusted to Novarka, a joint venture between the companies Bouygues and Vinci.

"Unique project, this arch will envelop and surround the current shelter."

It is intended to retain the radioactive material, to ensure the protection of workers on site and protection of the existing shelter against weather damage, and will eventually lead to the dismantling of the unit 4 of the plant.

The New Safe Confinement, a unique technical achievement
Consisting of a metal frame of 2500 tons, the shelter reaches colossal 108 meters high, the equivalent of a 30-story building, 162 meters long and a range of 257 m, dimensions that would cover the stadium "Stade de France".

 

Based on two concrete beams, the shelter is assembled on land adjacent to the reactor, about 300 meters away, allowing workers to withdraw from toxic radiation. Once assembled, the arch will be slided over the rails by jacks, until it reaches its final position above the existing shelter. The movement on rail tracks makes it possible to reduce vibration level during the travel of this huge structure.

 


DIALOG equipment installation
The company Jean Lutz was selected to provide instrumentation that monitors implementation of the piles that support the rails. It has installed Dialog devices on drilling equipment for measuring the position of the piles, via a GPS system, the verticality / deviation, downhole pressure during concreting, and the resulting profile of the pile.

Control of verticality is a critical point of this phase of the project, because the underground proves heterogeneous and the drill could be deflected by buried objects.

The DIALOG GPS works by using two sensors located at the top of the auger, and a ground sensor, so that the location is specified with high accuracy, in the range of 3 cm.


The second factor that specifically qualifies the Jean Lutz equipment is the special nature of the work environment and safety standards framing the intervention of operators on the Chernobyl site. Indeed, the time to work near the reactor is limited to 1 hour per day per person. After this time, the personal dosimeter measuring the technicians's exposure to radiation indicates that the daily dose is reached.

The instrumentation must be complete, as reliable as possible to avoid any repairs or maintenance that would lengthen construction time, but also simple and easy, so that operators can work quickly and intuitively.


Instrumentation at work
In 2013, two specialists of Jean Lutz were sent there to mount the equipment, operate tests, and train operators. "The result in progress indicates that the equipment is fulfilling its functions, because for entry into service in April, in the space of six weeks, 20% of the piles have already been made," said Marc Lutz, who himself oversaw the startup of the equipment on site.

 

 

 

 

The planning of the project includes an assembly of the arch during 2013-2014, the installation of systems in 2014-2015, and moving the arch to its final position for entry into service in 2015.

To go further on the subject:

Photos : © Jean Lutz SA.

 

 

 

);