Following the Energy Act 2004, the Nuclear Decommissioning Authority (NDA) was formed for the decommissioning 12 nuclear sites located throughout the United Kingdom.
In October 2016, Amber Precast Ltd. secured a £20m contract to manufacture the Magnox 6m3 Reinforced Concrete Boxes (RCB). These highly advanced Reinforced Concrete boxes are used to store active nuclear waste securely, for the next decennia.
The nuclear sector is a highly regulated industry. All reinforcement in the 6m3 Reinforced Concrete Box (RCB) has extremely strict requirements, relying heavily on the perfect positioning of the rebar components.
This is one if the reasons that Amber Precast contacted SKEW for a bespoke JIG Solution.
Image 1: JIG System Design proposal
The RCBs reinforcement is designed around a twist lock assembly (special handling feature), to be merged with a separate lid. The complex reinforcement arrangement, and the fact the bins are assembled upside down (on the mould’s base) were limiting the assembly choices for prefabrication.
In close collaboration our engineering team broke down the diverse assembly steps to then be able to propose a specialized JIG System for exact, efficient, and convenient reinforcement positioning.
Positioning pins were incorporated for the support of horizontal reinforcement before the structure being tied together. Specially spaced slots are integrated in the design to position the complex pre-merged stirrup configurations.
As an additional feature the entire Setup is designed for segments to be added or removed when called for. Being highly modular, the SKEW JIG System easily allows alterations to be made, both in configuration of the setup and the assembly procedure, when required.
After the ramp-up, a production of 10 reinforcement cages per week was achieved.
Image 2: JIG System and reinforcement
Image 3: Full reinforcement Assembly. Source: www.amberprecast.co.uk
Once the JIG System sections are removed, the corner twist lock arrangement and the remaining reinforcement can be added to complete the reinforcement cage, for casting.
Image 4: Completed 6m3 RBCs Source: www.amberprecast.co.uk
In August 2019, Magnox approved the procurement of the full manufacturing plant that would allow for production of up to 6 concrete boxes per week.
In August 2022, the first ever active 6m3 active waste package was successfully completed at the waste encapsulation plant. Radioactive waste is safely placed inside the 6m3 Reinforced Concrete Box. The concrete lid is remotely cast for secure sealing. Then the bins are stored safely in an underground depot.
Read More: Case Study by Amber Precast