ITER Leak Detection Systems closer to manufacturing

Maintaining a perfect vacuum is essential for achieving and sustaining a fusion reaction. ITER, the largest fusion experiment, will rely on extraordinary vacuum systems that will keep the vessel, cryostat and neutral beam injectors in low-density conditions required for operation. Any impurities that make their way in could disrupt it and compromise safety.

Fusion for Energy (F4E) is responsible for providing the Leak Detection System (LDS). This technology will allow experts to locate and analyse leaks in ITER's vacuum boundaries in a swift and accurate manner. How? The system will use an analytical technique called mass spectrometry. In a nutshell, helium will be used as a tracer gas, injected from the outside and, in case of penetration, detected inside by a high-resolution spectrometer.

The LDS will monitor roughly 2000 entry points in the cryostat, the vacuum vessel and the neutral beam injectors. It will do so through eight sub-systems, each designed to monitor different vacuum systems and phases of ITER operation. Some will work during plasma operation, whilst others during commissioning and maintenance.

"It's a critical system that needs a quick response time to detect leaks, characterize them and minimize their impact" stresses Roger Martín, Project Manager at F4E. "Even though we are using standard technology, its adaptation to ITER's requirements is what makes this project challenging," he adds.

After years of preparing the specifications with ITER Organization, F4E is now leading the design of the LDS. The team has completed the final design review of three sub-systems and plans to finalise them all by mid-2025. This stage includes the qualification of components, undergoing a series of strain tests. The equipment must prove it can withstand the harsh conditions in ITER, such as intense radiation, magnetic fields, and even unforeseen events like earthquakes, fires or over-pressure.

A turbomolecular pump controller, part of the Leak Detection System, under test at the ITER site. ©F4E

Roger Martín takes pride in the progress of the LDS, driven by the diverse expertise within his team: "From mechanical and piping design to vacuum engineering or instrumentation and control, we have grown into a resourceful group. We have managed to find cost-saving solutions and apply lessons learnt to the remaining sub-systems." Soon after the design is completed, F4E will launch a call to manufacture, assemble and test the whole system.

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