STEP divertor swirl tube concept design
STEP (Spherical Tokamak for Energy Production) is an ambitious programme to deliver a prototype fusion power plant by 2040 and provide a pathway to commercial fusion.
The programme is divided into three distinct phases. The first phase aims to produce a ‘concept design’ by 2024. This is an outline of the power plant, with a clear view of how each of the major systems will be designed.
One of these is the cooling system, which includes a swirl band tube to cool the STEP divertor target facing the plasma. This type of tube has an insert in the form of a tape to increase turbulence and hence heat transfer.
The UKAEA (UK Atomic Energy Authority) asked IDOM to critically analyse the existing design and propose improvements. The project consisted of a thermo-hydraulic analysis using CFD and system code tools and a mechanical analysis and evaluation including manufacturing.
The current design was challenged by the use of a different turbulence enhancing geometry that can achieve better performance and can be optimised to remove more heat from higher flow surfaces inside the tubes.
The final proposal was submitted in a patent application as it is a novel concept for cooling this type of high heat flux component.