Work to remove the top ducts from the heat exchangers at Calder Hall began back in 2008 as part of a six year contract working with Hertel and Mammoet. Twelve of the 16 top ducts have now been successfully removed, the top ducts weigh around 46 tonnes each and due to their size and contamination levels they also pose a significant hazard.
Jamie Ketchen, project manager at Calder Hall, Sellafield Ltd explained: “The Calder Hall heat exchanger project has achieved efficiencies during this phase of the project by employing ‘economy of scale’.
“Learning from experience from the past heat exchanger top duct removals, allowed the team to develop a detailed scope of work for the remainder of the heat exchanger top duct and steel work strip contracts.
“When planning for this work we had to take many things into consideration, we had two main challenges, the first was the logistical management of bringing to site the 1200 tonne crane and its required 22 support wagons with ballast weights, jibs and rigging and ensuring the ground positions for the cranes were suitable to lift from. There was significant stakeholder management to block roads and modify security barriers to carry out the lifts.
“The second key challenge was something that we couldn’t control — the weather. The 1200 tonne crane needed to be booked seven months in advance so we couldn’t change the chosen date for its arrival. Luckily we managed to hit one of the best weather spells in the UK for a number of years.
“Our contract programme milestone was to remove three top ducts by mid March 2014. By looking at effective work integration patterns, interfaces with the Calder defueling teams, we achieved this by the end July 2013; way ahead of target.