Nuvia has successfully decommissioned one of the most challenging legacy hazards at the site of Trawsfynydd nuclear power plant, which consists of twin 236 MWe (gross) Magnox gas-cooled reactors shut down in August 1993.
The sludge filtering and drying vessel – which was constructed in the 1970s and named RB’s Tank after the late Trawsfynydd engineer, Robert Byron Jones – was a legacy of the site’s electricity generation era and had the highest level of alpha contamination ever encountered on site.
The safe conclusion of the project marks a major hazard reduction milestone for Magnox and an important step on the road towards delivering the site to a state of care and maintenance.
The vessel was contained using Nuvia’s modular containment system, ModuCon, a glassfibre panel structure mounted in a steel support framework which was designed and constructed for this project, but which Magnox can now retain and reuse for future C4 capability projects.
The challenging working environment led to the development of an innovative approach to the installation of the modular containment. A sectional rail system was designed so the partially constructed ModuCon could be constructed in a low radiation area and be pushed into position over the tank – minimising both dose uptake and the risk of contamination.
With the containment in place the team made numerous entries in to the C4 ventilated environment, using air-fed suits to size reduce the tank, vacuum any ILW waste, categorise and segregate the waste, to allow packaging and consigning to appropriate disposal routes. Magnox and Nuvia personnel worked together on the project.
"There were many technical challenges along the way, but by working together to develop an innovative solution, the project has been delivered safely, thereby removing a major liability from the site inventory and has left Magnox with a facility which will be a major help with the remaining decommissioning of the site into the future," a Nuvia spokesman said.
Jason Carter, Senior Project Lead for Magnox, said: "The safe conclusion of this project is a reflection of the professionalism and perseverance of the team working in these challenging conditions. The modular system will now be retained for future projects and the site will retain its C4 capability".
