STEP WP5 - Heat Pipe Design Challenge

Managing the heat exhaust from a fusion reactor is one of the most pressing challenges facing those seeking to realise a commercial power plant design

For spherical tokamak designs such as STEP, the compact nature of the device potentially increases the heat fluxes on the plasma-facing components and restricts the space for incorporating cooling when compared to conventional larger aspect-ratio tokamaks such as ITER or EU-DEMO.

A fusion reactor heat exhaust is handled via a divertor, which needs to handle large heat fluxes (>10 MW.m-2) especially in the divertor target

2Heat pipes have been proposed as potential technology for fusion high heat flux components since at least 1972. Liquid metal filled heat pipes have been tested under fusion relevant heat fluxes as recently as 2018. Despite this, there remain significant outstanding questions before they can be considered as a feasible solution for the fusion heat exhaust problem

The STEP Work Package 5 (Resilient Nuclear Components) wishes to harness industrial expertise in heat pipe design outside the fusion community and to identify whether this expertise can be applied to developing an innovative heat pipe concept design for the STEP divertor target.

This design challenge is ultimately concerned with the feasibility of implementation for a heat pipe high heat flux handling solution within the divertor region of a fusion reactor.

The UKAEA is seeking the assessment of innovative preliminary concept designs of a high heat flux heat pipe suitable for use as a STEP divertor target.

The total duration of the activities of this initial contract shall not exceed 12 weeks and must be completed by March 2020.