Ensuring the structural integrity of tokamak fusion power plants: challenges, progress and pathway

Structural integrity for fusion is an integrated multi-disciplinary subject spanning the science of materials, technology, engineering, health monitoring and simulation methods and algorithms for scrutinizing the assurance of reliable fusion reactor performance from the whole plant design phase through operation to decommissioning. Structural integrity is essential for maintaining high standards of public, environmental and investment protection and maximizing economic benefits. While fusion shares many of the structural integrity challenges faced by other industries, it also presents unique complexities. These include distinct regulatory requirements compared with fission, the need for innovative materials suited to extreme environments, advanced manufacturing techniques for component fabrication and the establishment of new facilities for technology demonstration, design verification and validation. Additionally, developing qualification processes, design rules, lifetime assessment methods, procedures, codes and standards is essential for verifying fusion reactor designs and predicting the lifespan of systems, structures and components. This paper reviews the challenges and advancements in fusion structural integrity, focusing on the tokamak concept and key in-vessel components: the breeding blanket and the divertor. It covers fusion regulations, operational environments, load cases, multi-material joints and the creation of fusion-specific design criteria. The paper concludes with a recommended pathway for future research, development and collaboration to advance commercial fusion energy.This article is part of the theme issue 'Future challenges for structural integrity of high-integrity components'.