In-Vessel Assembly

A comprehensive review

17 Mar 2025 - Anna Encheva, In-Vessel Assembly Project Leader

On 30-31 January, the ITER In-Vessel Assembly Project conducted a comprehensive review of the assembly and installation processes for key in-vessel components, including the in-vessel coils and the blanket and divertor systems. The initiative aimed to review the installation activities by optimizing the sequence, tools, and logic underpinning these critical installation activities, which are projected to last a little over two years. 

Specialized tools (in blue) have been designed for the installation of in-vessel components such as blanket shield blocks, blanket first wall panels, cooling manifolds (bundles of piping), and in-vessel coils, which must be transferred mechanically through an ITER port cell and into the vacuum vessel, then positioned inside the vessel with as little operator intervention as possible.

The integration of a large number of complex components in the constrained environment of the vacuum vessel will require careful planning and execution. The review in late January, chaired by Doug Loesser from the Princeton Plasma Physics Laboratory (PPPL), was organized to carefully examine the proposed assembly sequences, to ensure logical interdependencies and efficient workflows. 

Specialized tools—such as the in-vessel tower crane, the blanket assembly transporter, the divertor assembly transporter and other bespoke handling devices—underwent detailed assessments to confirm their suitability for the assembly process, with potential refinements discussed to maximize efficiency. Strategies were identified to enhance installation operations while also addressing potential bottlenecks and constraints.

A key aspect of the review meeting was to align the installation schedule with overall project timelines. Identifying potential misalignments and mitigating technical challenges through rigorous risk assessment are both crucial aspects to ensuring that the schedule remains realistic and achievable and preventing delays and cost overruns. 

Participants to the assembly and installation review organized in January for key in-vessel components.

Since 2015, the tools needed for in-vessel assembly have been under development and testing. Several handling facilities, including a Trial, Test, and Training Facility, will soon be available for use on site, providing a valuable resource for process qualification and personnel training. Lessons learned from recent trials indicate that some upgrades are necessary to enhance functionality, particularly for the blanket assembly transporter, which will play a crucial role in the installation strategy we are planning. Unlike the tower crane, which operates on rails in the lower part of the vessel and will be used to install the divertor, the blanket assembly transporter is port-based, allowing for the concurrent installation of blanket and divertor components, significantly improving efficiency.

Several refinements have also been proposed to simplify divertor installation, which are being organized through the Domestic Agencies that are providing divertor components.

ITER intends to collaborate with an industrial partner for the complete development of those assembly and installation processes and for the execution of onsite works.

By integrating lessons from previous trials, refining tool functionality, and fostering collaboration among stakeholders, the in-vessel assembly strategy is evolving into a more efficient, cost-conscious, and schedule-aligned approach.