Integrating the many systems that make up the Tokamak machine is a lot like delivering a clash-free layout for the engine room of a modern nuclear submarine, only on a much grander scale. Introducing the HIT team—a group of engineers, designers and contractors that has been selected to take a hard look at the overall integration of systems in ITER's main nuclear buildings and to propose solutions for clashes and constructability issues.
They have been chosen from engineering and construction departments at ITER, the European Domestic Agency buildings team, contractors, suppliers, and the Domestic Agencies. A core team of about eighty people who, while remaining under the responsibility of their original line management, are sharing office space near the construction site in order to perform "joint integration work"—that is, to ensure that i's have been dotted and t's crossed before the large-scale assembly and installation of plant systems begins in the Tokamak Complex.
Working through the areas of the Tokamak Complex one after the other to scrutinizing all systems elements and resolve any issues: the Holistic Integration Team, formed in 2018 from representatives of all stakeholder groups.
Formed in March 2018 by the ITER Director-General, the HIT—for Holistic Integration Team—has been given the role of "collaborative system design integrator," says coordinator Miikka Kotamaki. "We are in charge of delivering a clash-free design and optimized system installation sequences for every area in the Tokamak Complex."
The HIT team works by area (i.e., by building and level), and assesses all available system design elements for completeness, consistency and constructability. The group has developed an "integration lifecycle" that it works through to ensure that all issues have been resolved (see below). "The integration cycle is a kind of 'Snakes and Ladders
' template, based on the previously tried-and-tested model of the Buildings Infrastructure and Power Supplies (BIPS
) Project Team," says Deputy Coordinator Roger James Holt. "We use it to make sure that all 'ladders' are climbed at the right time and 'snakes' avoided." (More on the integration lifecycle here
Applying the integration cycle
1 — The team reviews the consistency of system designs and the implementation of "transverse" functions (fastening systems, supports, access). Following a final completeness evaluation, the layouts are frozen in CATIA, ITER's computer-aided design platform. [~1 month]
2 — Through an automatic detection process in CATIA the layouts are scrutinized for clashes between systems. Any clashes are identified in the models with a unique number and analyzed. Workshops are held to decide on clash resolution actions. There are implemented in the new model in accordance with all system owners. [~2 months]
3 — In the last phase of the cycle, the team moves on to consider assembly sequences, overall constructability in the zone, and 4D planning. The process ends with the approval of the final configuration model. [~3 months]
- If no easy technical solution exists, team engineers and architects collaborate to solve the issue (i.e., develop a common support mechanism).
- The new solution is assessed for suitability and constructability, taking into account any changes introduced relating to civil works.
It was in executing this kind of step-by-step assessment that one part of the HIT team began looking more closely at the passage of services and utilities through the Tokamak Complex walls and floors.
As the massive structure rises, thousands of openings have been left in the civil works for the passage of ventilation, electricity and cooling water. These openings will eventually be backfilled with concrete—but first, "placeholders" must be installed, such as tubes for the future passage of piping or sleeves for electrical cabling.
A support structure is needed to hold equipment placeholders (top) while backfill is poured. In the original concept, a stainless steel frame (bottom) was to be custom-made for each opening.
The initial design concept proposed stainless steel frames to support the placeholders—each one machined off site to match the particular layout requirements of each opening (see diagram, right). "This solution seemed to present a long list of disadvantages," says Caroline Dixon, technical lead for the ENGAGE team developing detail design of the backfilling of the openings. "Each frame had to be custom designed; manufacturing was costly and time consuming; and the weight of the final frames—up to 500 kgs—would have made specialized handling tooling necessary in the Tokamak Complex."
The team concluded that—while the custom-made frame may be justified in particularly complex openings—the majority would be just as well served by a simpler, standardized solution. By benchmarking practices at other large construction sites and working with local industry to adapt a solution for ITER, the HIT engineers arrived at a modular solution with adjustable positioning elements.
The modular support system developed within the HIT team allows installation contractors to build the support system directly on site, representing time and money saved for the ÏTER Project.
"The solution is like modular shelving—lighter and more flexible, easier and cheaper to fabricate and install, and based on standardized elements that can be stored in bulk on site." Provided with a table indicating the exact location of the penetrations that must be reserved in each opening, installation contractors can put together the required support system right in the field.
The flexibility, ease-of handling, and lower cost of the solution clearly convinced ITER Organization management, which recently gave its approval during a monthly review meeting with the HIT team. It was just one demonstration among many of the positive impact the HIT team has had since its formation six months ago.
"This design solution is a concrete example of how the HIT team is identifying and resolving problems associated with the co-existence of numerous services to be located in the same area/room of the Tokamak Complex Building before assembly and installation works get underway," says Bernard Bigot, ITER Director-General. "By taking a high-level view of all plant systems in the Tokamak Complex and executing concurrent engineering activities, the HIT is critical to secure the project's assembly phase schedule and cost."