Thu, 10 October, 2024
TWI has recently contributed to a journal article written by UK Atomic Energy Authority (UKAEA), in conjunction with Frazer-Nash and TWI, titled, ‘Manufacturing trials of PFCs with low thermal conductivity features for limiters’, which features in Volume 206 of Fusion Engineering and Design.
The article is a result of a project delivered by TWI’s Senior Project Engineer, Alex Russell, Manufacturing Support Manager, Paul Brooker and Team Manager, James Redman under the STEP (Spherical Tokamak for Energy Production) Manufacturing Support Services Framework, established to support the design and construction of the UK’s prototype fusion energy plant in Nottinghamshire that will generate electricity for the National Grid.
The article highlights the engineering challenges associated with the future demonstration of fusion power plants, and specifically the job of plasma-facing components, which can be subjected to high steady state and ultra-high transient heat loads from the plasma. Plasma-Facing Components (PFCs) optimised for steady-state operations require high thermal conductivity in order to minimise thermal gradients and stresses for a given heat flux. The introduction of low thermal conductivity features to the plasma-facing component can reduce the peak temperatures seen by the coolant pipe during transient loads, but at the trade-off of a loss of steady-state performance. The result of low thermal conductivity features can be seen in figure 1 (below).
Figure 1. Monoblock surface temperature distribution at steady-state. The average front face temperatures and overall peak temperature are labelled (image courtesy of UKAEA)
Some highlights from the article include:
- Limiter PFCs can use lattice or porous geometry to protect coolant pipes
- Machining of holes in tungsten reduces the effective thermal conductivity
- Effective thermal conductivity reductions of 15% to 40% were achieved
- No evidence of cracking after high-heat flux testing for 500 cycles
- Tungsten machining is high-TRL compared to additive manufacture approaches
A link to the full article, which is open access, can be found here.
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