PLC upgrade helps Sellafield keep its cool
Schneider Electric has upgraded the programmable logic controllers and software which control the ion exchange effluent plant at the Sellafield facility.
The ion exchange effluent plant features a waste matter process that removes radioactivity from a number of outlets across the site and is critical to the facility's operations. Waste material, which generates heat, is kept in ponds and these need to be chilled to keep temperature constant.
As the original provider, Schneider was called in to manage the upgrade project. Phil Woods, services and support manager for Schneider Electric, said: "The system was previously controlled by five Modicon 684 PLCs, which were installed when the plant was built. One of the biggest issues was the requirement to create software that closely resembled the original version so that it was familiar to Sellafield's process engineering team. This was necessary to ensure minimum disruption to the plant and reduce the need for radical retraining. At the same time, we had to implement programs that are compatible with IEC61131-3 open control system standards, bringing it in-line with modern regulations."
To meet the requirements, five Modicon Quantum PLCs were installed, each fitted with Cablefast 'plug and play'. Woods continued: "Essentially the five Quantum PLCs are arranged as two pairs that perform identical functions and the fifth as an individual unit, carrying out different functions from the others. One pair of PLCs is in use at any time and while this is not a truly dual redundant system, the operator can switch between the two pairs of PLCs."