Sellafield SIXEP Continuity Plant nears 2029 start

Crane lifts do not usually sound like a big public story, but at Sellafield they tell you something important: a clean-up project is moving from drawings and plans into real machinery. In the government’s update, Sellafield said the SIXEP Continuity Plant, or SCP, has passed a fresh construction milestone after teams completed a series of major lifts on site. That matters because this is not just another industrial building. The new plant is being built to replace the current Site Ion Exchange Effluent Plant, known as SIXEP, and Sellafield says it is now around three-quarters complete and still on course to begin operating in 2029. If you want the short version, this is the plumbing-and-process side of nuclear clean-up: quiet, technical work that helps keep a high-risk site safe.

**What the plant actually does:** water used in site operations can pick up radioactive material. Before any of that water is discharged to sea, it has to be treated so that radioactive material is removed. The current SIXEP has been doing that job since 1985, which helps explain why a replacement matters. Sellafield often describes SIXEP as the site’s ‘kidneys’, and that comparison is useful if you are new to this subject. Kidneys filter what the body does not need. This plant filters radioactive material out of operational water. The wording may sound gentle, but the purpose is serious: without treatment systems like this, long-term work at Sellafield would be much harder to carry out safely.

The latest milestone was not just symbolic. Teams moved 14 pump and valve modules into position, with each one weighing 16 tonnes. They also installed a gantry crane weighing 55 tonnes and stretching 21 metres across the plant. When you read numbers like that, it helps to picture the scale. These are not small parts being wheeled through a doorway. They are large, pre-built pieces of the plant that have to land in exactly the right place. **Why lifts like this matter:** on a nuclear site, heavy lifting is never only about strength. It is about planning, timing, safety checks and precision. One module in the wrong position can hold up the systems around it, so a successful lift tells you that design, manufacturing, transport and on-site installation are starting to line up properly.

According to the government update, the main buildings are already complete and protected from the weather. That is an important point in any major construction job, because it means attention can shift from the outside structure to the inside of the plant, where specialist equipment, pipework, control systems and other operating kit are fitted. **What this means for 2029:** being three-quarters complete does not mean the plant is nearly ready to switch on tomorrow. Nuclear facilities go through long periods of installation, testing and checking before operations begin. In plain English, the shell may be up, but the careful part now begins: making sure every internal system does the job it is meant to do, and does it reliably.

That steady pace matters because the new plant is expected to keep doing this work until at least 2060. Sellafield says it will support the site’s wider mission of reducing risk and moving forward the long clean-up of some of the UK’s most hazardous nuclear materials. This is the kind of infrastructure that can look dull from a distance, yet it carries much of the real safety work. It also sits inside a bigger public question: how do you manage radioactive waste and contaminated water in a way people can trust? Plants like SCP are one part of that answer. They do not make nuclear risk disappear, and they are not meant to. What they do is treat operational water before discharge and keep an essential safety system running for decades, which is why replacement work cannot simply be left until the old plant wears out.

The project is being delivered through Programme and Project Partners, or PPP, which brings together Sellafield Ltd, KBR, Amentum, Morgan Sindall Infrastructure, Altrad Babcock and a wider supply chain. The update also notes that PPP is marking seven years of delivery at Sellafield, having been established in 2019. Steve Harnwell, PPP’s managing director, said the arrival of operational equipment followed years of design, engineering and manufacturing, and that each major project at Sellafield helps manage and reduce the UK’s most hazardous nuclear materials. For us as readers, there is a useful lesson here. Big national clean-up jobs do not only move forward through dramatic breakthroughs. Sometimes progress looks like 14 modules, one gantry crane and a weather-tight building in Cumbria. If you want to understand how nuclear clean-up really happens, this is a good place to start: not with slogans, but with the slow, expensive and necessary systems that keep the whole site working safely.