Pumps help out at nuclear sludge processing plant

Peristaltic high-pressure hose pumps are playing a key role in decommissioning a number of UKAEA nuclear facilities at Winfrith, Dorset.

One of the UK's largest private nuclear service providers, RWE Nukem, has an eight-year contract to maintain and decommission a number of UKAEA's nuclear facilities at Winfrith, Dorset.

A waste treatment plant, designed to process legacy low end intermediate level radioactive waste (ILW) ion exchange resin sludge by cement encapsulation, has been designed and built.

This key facility uses Watson-Marlow Bredel's peristaltic high-pressure hose pumps.

The nuclear facilities, which ceased operations in 1990s, were identified for decommissioning as part of the site restoration and UKAEA turned to one of the experts in the industry, RWE Nukem to carry out this task.

The radioactive sludge, which is to be held in an interim store for some years, needs to be kept in manner that allows for safe packaging and transportation to a secure store.

This process required RWE Nukem to build a specialist plant on the site to encapsulate the sludge.

This is done by mixing the sludge with cement and packing it into drums.

The process involves retrieving homogenised sludge from existing tanks, pumping sludge through a crossflow filter system to dewater it, and then discharging batches of conditioned sludge to the drums.

The heart of the encapsulation process is dependent on peristaltic pumps from the Watson-Marlow Bredel SPX range, including two SPX 65 models and another two SPX 80 models.

The pumps were sourced by Poole Process Equipment, who produced a detailed piping design, as well as carrying out manufacture and installation of the pipework and pumping system for the encapsulation plant.

Richard Chacksfield, Project Engineer from RWE Nukem comments: "Using a pump that could be mounted on the outside of the tanks containing radioactive sludges meant that having a high suction lift was an important criterion for the pump.

Using submersible pumps in this environment was not an option; equipment reliability can be compromised and maintenance can become problematic".

The damper vessels on the suction and discharge were specially designed for the encapsulation plant's flow pulsation by Watson-Marlow Bredel and manufactured by Poole Process Equipment.

The SPX65 and 80 pumps are also able to act as accurate metering pumps, which is important for controlling volumes of the sludge.

The fact that they can cope with solids laden and erosive process streams made the SPX ideal for the harsh nuclear environment.

"After having looked at various alternative products in the market place, Watson-Marlow Bredel's SPX range came out head and shoulders above the rest.

In addition to meeting all the requirements, they were also relatively compact.

Furthermore, the use of a peristaltic hose with a machined internal bore will ensure that metering accuracy and suction lift is maintained throughout the pump life".

Apart from providing the performance, ease of maintenance and compact construction, the SPX range from Watson-Marlow Bredel has direct-coupled design that allows the drives to be removed and replaced without having to dismantle the pump head.

Pumps are available in a variety of sizes from 25 to 100mm.

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