RSRL’s waste handling gathers pace with 5,000th can

August 2, 2011

Dealing with the legacy waste at RSRL Harwell is a central part of the site programme. In July, RSRL achieved a notable landmark – the processing of the 5,000th waste canister.

Alan Neal, RSRL Managing Director, comments, “5,000 cans is a considerable milestone - an achievement only made possible by hard work and continuous improvement.”

Processing

Waste recovered from the retrieval process is transferred to Harwell’s Head End Cell suite in the Solid Waste Complex, where it is processed – assayed, decanted and examined. From there, it is put into 500-litre drums, approved by the NDA's Radioactive Waste Management Directorate, for storage in the Vault Store.

Following on from the 5,000th waste can, a further 6,000+ cans will be processed through the facility before the plant completes its purpose. The honour of assisting in processing the 5,000th waste canister, using remote handling equipment, went to NDA Programme Manager David Rushton.

Improved throughput

The processing of cans through the Head End Cells began in 2003. In the early years, around 350 cans a year went through the facility. Since then, thanks to the introduction of system of Overall Equipment Effectiveness (OEE) aimed at driving out inefficiencies, this figure has risen year on year, until it is almost double the original figure.

“This efficiency process is rapidly becoming recognised as best practice by stakeholders and regulators alike,” says Project Manager, Gary Preston. “A high value PBI (Performance Based Incentive) target is set on this plant by the NDA – a base of 591 cans and a stretch target of 650, for this financial year. Currently, we’re on schedule to achieve the base target and will be working hard to achieve the stretch target.”

Ensuring consistent feedstock

However, increasing throughput has not been without its difficulties, as Gary Preston goes on to explain: “With equipment so complex and remotely operated, breakdowns provide a challenge across many disciplines. To achieve such an improved throughput consistently relies on an adequate feedstock.”

Feedstock comes principally from Retrieval Machine 2 (RM2) – the 240-tonne, fully shielded and contained moveable cell, used to recover intermediate waste, stored in underground storage tubes on site since the late 1950s. Its forerunner, RM1, and other waste streams provide the balance. Problems with any of the machines recovering waste starve the feedstock and hence the throughput drops.

Not only this, any pieces of equipment used along the critical path from recovery to process – from cranes to vehicles – can affect the result. The same goes for the Head End Cells themselves. Any problems there stop not only the processing but also the recovery programme, as the recovered waste has nowhere to go.

Rapid response

To ensure breakdowns are repaired quickly, the Solid Waste Complex has its own resident RSRL staff, able to deal with the many and varied problems that arise. Over the years they have encountered a wide variety, from failures in the can and debris grabs and the cell hoist, to damaged hoist and power cables, as well as problems with ventilation, sealing and decontamination.

“On one occasion the grab became stuck within the storage tube and could not be removed,” Gary Preston remembers. “We tried many techniques to release it without success”.

“Eventually, while a number of options for recovery were taken forward, the persistence of the operations staff paid off and the grab was released. Because of the nature of the diverse waste we deal with, such faults are difficult to predict – but we learn from these events. We now have built-in provision to deal with the situation with the grab, should it ever happen again.”

For more information contact Angela Vincent, RSRL Communications Manager