Leading British conveying and handling specialist Exmac Automation has provided a bespoke conveying system to King Transport Equipment to transfer drums containing nuclear waste via two specially designed trailer units that are used to transport low-level nuclear waste within the Sellafield reprocessing plant.
King Transport Equipment, the largest manufacturer of abnormal load trailers in the UK, has produced a number of successful trailer solutions for the nuclear industry prior to being awarded its first major contract to project manage the turnkey design and manufacture of two containerised Drum Transfer Trailers (DTTs). The DTTs replace a 20-year-old system used to transfer drums containing nuclear waste from the loading bay to secure storage at Sellafield.
The bespoke Exmac conveying and handling system is fitted inside the DTTs to enable drums to be transferred into the trailer-mounted container from an external conveyor. Drums can then be discharged from the trailer onto a similar conveying system on the Sellafield loading bay, one of which is already fitted with an existing Exmac conveying system. The system comprises a matched pair of heavy duty slider-bed belt conveyors, each capable of handling a maximum payload of up to 6.8 tonnes of waste drums (maximum weight of an individual drum is 1.7 tonnes).
The system incorporates many special features including:
- Remote drive systems with overload protection; and manual drive systems mounted within a separate maintenance compartment to allow access for maintenance personnel.
- Cassette structure with sliding feet arrangement to allow easy removal of individual conveyors for major planned maintenance operations.
- Powered rise and fall barrier to contain drums on the conveyors during transfer and transportation. The barrier is raised at the beginning of the load/unload procedure and again at the end, by an input signal.
- Fixed barriers to retain drums in the event of the trailer being subject to sudden braking or a low speed collision.
A spokesman for King Trailers says the company had worked successfully with Exmac on a previous aerospace project and contacted them again to design and manufacture the integrated transport and handling system that would allow the purpose-designed DTTs to interface with Sellafield’s internal conveying system.
Besides replacing equipment that had come to the end of its useful life, Sellafield’s specification also required the new installation to address some of the shortcomings they had experienced with the old system.
The previous system consisted of demountable containers with retractable hydraulic legs, which were fitted onto the backs of rigid vehicles. At the loading bay the legs were jacked down so that the units remained in position for unloading when the vehicle tractor units were driven away. In contrast, the new DTT systems consist of an articulated trailer that is reversed into the loading bay, where they dock with specific fixing points that physically lock the trailers into position. The trailer/container, which includes the Exmac conveyor transfer system, remains locked in position at the bay when the tractor unit is driven away.
The DTT is a three-axle trailer designed to transport a mix of either 210 litre or 500 litre drums of low-level waste material. The gross capacity of trailer and payload is limited to 32 tonnes.
