The Project
As industry recognised experts in the manufacture of high integrity welded structures, LTi was approached by fusion energy pioneers Tokamak Energy, to manufacture a pressure vessel vacuum chamber for the company’s innovative spherical Tokamak ST40 fusion reactor prototype.
LTi’s support would be vital in enabling Tokamak Energy to manufacture their reactor – a world-first reactor at a fraction of the standard industry size, offering the potential to eliminate the legacy problems of radioactive waste and another solution to help beat the energy crisis.
By combining high-temperature superconducting (HTS) magnets with spherical tokamak technologies, the ST40 reactor is able to produce the perfect conditions for fusion power with plasma temperatures that are even hotter than the centre of the sun. The fusion reaction process itself is then generated when the hydrogen isotopes deuterium and tritium within the plasma collide and fuse together to release huge amounts of energy.
Given the globe’s unsustainable reliance on fossil fuels and the ongoing fight against rising carbon emissions, fusion energy is so exciting, as it offers the potential to produce clean and virtually limitless energy supplies.
The Challenge
In this project, LTi needed to identify and create a new vacuum vessel chamber design that could meet their customer’s specification, performance and quality requirements and be delivered within their time-frame.
However, in order to achieve this there were a number of challenges they would need to be able to meet:
- The final fabricated vessel structure would need to be able to contain plasma temperatures of 100 million degrees centigrade – seven times hotter than the centre of the sun
- They would need to maintain the highest levels of weld quality, as the criticality of pressure vessel integrity is no more acute than in the nuclear fusion sector, where the tolerance and integrity of seals leaves absolutely no room for error
How LTi went about it
Drawing on their extensive expertise of designing and manufacturing high-end pressure vessels, LTi was able to turn Tokamak Energy’s ideas into reality with a strong stainless-steel structure.
Working to EN 13445 European Pressure Vessel Standards, which sets the required minimum standards in the design, fabrication and inspection of vessels, LTi conceptualized an IVC Angled Support Fabrication structure, which they developed through a number of steps:
- Single-sided welds containing gap requirements for a backing at a minimum of 4mm, which were extended to 10mm from the edge of the joint to prevent burn through
- These welds were engineered with a raised surface around the flanges to act as location and weld backing
- Solutions were also identified to reduce welding times, by eliminating the requirement to grind back on some of the double-sided welds
- The structure was simplified whilst maintaining function, by placing prep angles and creating square edges on the coned features
- The design was also enhanced to make the IVC outer wall cylindrical, so that the resulting voids inputted would not affect the cone sections
What was the outcome
LTi was able to successfully develop and deliver a pressure vessel structure that met their customer’s specification, high levels of quality and time-frame requirements.
Such was the level of innovation achieved by LTi on this project, that their role culminated in them winning the ‘Best Research & Development Project’ category at the Cotswold Life Engineering, Manufacturing & Innovation Awards in 2017.