Coil geometry with large openings for a HSR3-like stellarator reactor for fast replacement of in-vessel components

TL;DR

This paper proposes a novel coil geometry for the HSR3 stellarator reactor that features large openings, facilitating easier remote maintenance and larger blanket modules, potentially reducing shutdown time and costs.

Contribution

The study introduces a new coil configuration with wide openings in the HSR3 stellarator, improving access for maintenance and enabling larger blanket modules compared to traditional designs.

Findings

Coil geometry with wide openings allows larger blanket modules.

Design reduces remote maintenance complexity and reactor downtime.

Potential for cost savings in stellarator reactor operations.

Abstract

Advanced stellarators require convoluted modular coils to produce a plasma with satisfactory performance. Moreover, the number of coils is sometimes high to decrease the modular ripple created by the coils. For reactor stellarators, these requirements imply relatively small ports for in-vessel access and maintenance, i.e. in comparison with tokamaks. The blankets and divertor modules will have to be replaced periodically (about each 1-4 years depending on the design) due to neutron damage, and also erosion of divertor targets. Blanket modules are activated, thus, all the maintenance operations have to be produced remotely. In order to reduce the shutdown time and cost during component replacement, and to reduce the number, speed and other specifications of the remote maintenance equipment, the number of blanket modules in the reactor should be low and thus, the blanket modules should be large (in relation to the minor and major radius). Nevertheless, the size of the openings between coils limits the maximum size of the blanket and divertor modules, though several potential enhancements have been proposed in the past for stellarators, like straightening the outboard segments of the coils and the movement and/or expansion of certain coils to have wider access. The present work reports on a coil geometry for the 'Helias Stellarator Reactor' (HSR) of three periods (HSR3) with coils located far from the plasma at the outboard region of the straight-like sector. This feature creates natural wide openings at such regions of the coils, which may be utilized to allow access to large blanket and divertor modules.