It’s been over 30 years since the explosion at the N°4 reactor at the Chernobyl Nuclear Power Plant in present day Ukraine. After the disaster in 1986, a makeshift shelter, known as the sarcophagus, was built around the reactor to confine the radioactive materials. It was never intended to be a permanent solution, and in November 2016 the New Safe Confinement (NSC) was slid over the damaged reactor and the original sarcophagus.
Built by the French Novarka, a Joint Venture composed of Vinci Construction Grands Projets and Bouygues Travaux Publics SA, the NSC is designed to prevent the release of radioactive contaminants from the existing shelter, protect the reactor from external influence, facilitate the disassembly and decommissioning of the reactor, and prevent water intrusion. It is designed to last 100 years and to withstand temperatures of -43°C to +45°C, as well as earthquakes and tornadoes.
The sheer scale of the structure is hard to imagine. The dome is 108 metres high (twice as high as Nelson’s column in London), 162 metres long and has an external span of 270 metres. Inside, work will later take place to decommission the plant, using gigantic remotely operated bridge cranes designed and manufactured by Minnesota-based PaR Systems, suspended from the arches of the dome. The cranes travel east to west on common runways, with a span of 84 metres.
Mirion, a leading manufacturer of radiation tolerant imaging solutions, was chosen as the systems integrator to design a video communications system in the NSC to monitor the operation of the cranes. In partnership with AES Systems a Fluidmesh wireless network was designed to replace an inefficient legacy system and integrated into the existing architecture without significant changes to enclosures or crane structures.
“There are two bridges and three carriages,” explains Glen Gardner of AES Systems. “These can be moved between the bridges, wherever you want them, but it means that they can’t use traditional network connectivity. They can’t use wires.” An additional complication is that the inside of the arch is lined with stainless steel cladding polished to a near mirror-finish and large concrete structures. Nevertheless, says Gardner, “The Fluidmesh system has handled this environment much better than the previous one, which suffered constant data collisions and packet loss.”
The video system consists of cameras placed on the various components of the crane system with monitoring located in a remote safe area. “We have 27 IP cameras giving us general views within the crane sphere of the new safe confinement,” says Gardner. “It’s not for security. It’s to monitor the placement, positioning and function of the cranes. We can also observe wheels, bearings, cable drums, etc.” Three of these cameras are high-radiation tolerant cameras manufactured by Mirion mounted on the underside of a tool platform to observe operations at the places where radiation levels prevent human entry.
The original system was equipped with two-channel radios offering 54 megabytes per channel. These were replaced with single channel Fluidmesh radios offering up to 500 megs. The other thing that impressed Gardner was the level of customer service offered by Fluidmesh. “They helped us every step of the way with the implementation,” he says. “My Fluidmesh partner helped me configure the system before we even took it to the site. Everything was configurable from here. They really partnered up and helped us overcome some technical issues. They did what partners do.”