ITER progresses into new baseline

Abstract

The ITER Project has gone through a period of transition, with progress continuing despite challenges, and is moving forward on the basis of a new project baseline. Repairs to key components—the vacuum vessel sectors and thermal shields—are progressing according to schedule. Progress has continued on construction, manufacturing, assembly, and system commissioning. Following more than a year of review, a new baseline proposal was submitted to the ITER Council in June 2024, and is now serving as the working reference schedule.

The discovery and analysis of geometric non-conformities in the bevel joints of several vacuum vessel sectors, as well as chloride corrosion cracking in the cooling pipes of the thermal shields, led to a slowdown in ITER tokamak assembly while repairs are carried out. In parallel, an assessment of root causes, including a thorough self-examination of project quality culture, was followed by a reorganization to prepare for the challenges ahead. Extensive discussions were held with the French nuclear safety authority (ASNR) to restore trust and evaluate strategies to enhance the safety demonstration accompanying ITER's licensing. Meanwhile, the power supply systems, the cryogenics plant, and several cooling water systems have completed installation and are largely commissioned. All poloidal and toroidal field coils have been delivered, as well as most of the central solenoid modules and many other major components.

The largest task over the past year has been to channel all these elements into a realistic, feasible updated project baseline. In the resulting proposal, the previously envisioned stages of assembly and operation are largely consolidated. Technical and operational risks are mitigated by replacing beryllium with tungsten for the first wall panels and incorporating the divertor, shield blocks, a sacrificial first wall, and other risk-reducing components into a more complete machine before initial operations, as well as fully testing some toroidal and poloidal field coils before their installation. The start of research operations (SRO) in 2034 will inaugurate a 27-month period of substantial experimentation with hydrogen and deuterium plasmas, to culminate in operating the tokamak with pulses of several tens of seconds at full magnetic energy and plasma current (15MA) in 2036. The SRO phase will largely demonstrate the integration of systems needed for industrial-scale fusion operations. The start of deuterium-tritium operations phase will be delayed by 4 years from the previous baseline, from 2035 to 2039.

Highlights from these areas (manufacturing, tokamak assembly, system commissioning), will be presented along with the updated baseline proposal and other aspects of project status.