Collaborative design for a large-scale nuclear treatment plant

Keeping nuclear waste safely under control

Sellafield is responsible for cleaning up and safeguarding the highest hazard nuclear fuel, materials, and waste on behalf of the UK’s Nuclear Decommissioning Authority (NDA).

The existing Site Ion Exchange Effluent Plant (SIXEP) has been operational at the Sellafield site in Cumbria since 1985, removing radioactivity from various wastewater streams and reducing environmental impacts. It acts as the ‘kidneys’ of the site by filtering out radioactive material before discharging to the sea.

Due to the age of the original SIXEP, which was only designed to operate for 25 years, an essential replacement is needed for effluent treatment of the site.

Delivering a next-generation treatment facility

A new treatment plant is being built to replace the existing facility. The SIXEP Continuity Plant (SCP) will be fundamental to high-hazard risk reduction activities.

As part of a multi-disciplinary team collaborating through Sellafield’s Design Services Alliance, we delivered concept, preliminary, and detailed design solutions during the initial phases of the new build, working as an integrated unit.

Driving collaboration through digital design

We played a key role in assisting Sellafield during the development of collaborative building information modelling (BIM) integration, across multiple disciplines in multiple locations. The SCP was the first major plant developed by Sellafield following implementation of the UK Government’s BIM Level 2 collaborative working compliance, now required on all public sector construction projects.

Under BIM Level 2, civil, structural, and architectural drawings are accessible to all team members at the same time, enabling various stakeholders to input into models in real-time, in parallel with analysis activities. This enables rapid production of intelligent drawings and schedule deliverables, alongside the engineering design. Overall, it creates a faster, more seamless design process, which in turns saves the project time, money, and resources.

Building for the long-term

The final business case for the SIXEP Continuity Plant was approved by HM Treasury in December 2021, three months ahead of schedule, and the plant is now under construction.

Having successfully delivered solutions for the detailed design, our team is now assisting with site support, issuing drawings for construction, and ensuring strong and consistent stakeholder management on any design changes required as the project progresses.

The new plant is expected to enter active commissioning in April 2029. With a design life of 50 years, it will reduce risks and minimise environmental impacts from effluent at the site for many decades to come.