The Chinese Domestic Agency has delivered the first part of the gas injection system, a series of pipes that transports all gases into the Tokamak Building from the tritium plant. Housed next to the Tokamak Building, the tritium plant is a highly sophisticated plant performing advanced chemical separation and purification, where the exhaust gases from the Tokamak are recovered, processed and stored for recycling or venting. 'The gas injection system will also carry other gases, including nitrogen, argon and neon, as well as two isotopes of helium and three isotopes of hydrogen, depending on the phase of operations,' says Paul Jordan, mechanical engineer in the Fuelling & Wall Conditioning Section. Two different piping systems—so called manifolds—will be put in place: one is called the gas fuelling manifold, feeding the torus for plasma operation; the other, called the neutral beam manifold, delivers hydrogen and deuterium to the neutral beam heating and current drive system. Within each system is a central evacuation pipe, which transports vented gases to the tritium plant, where they can be processed. Around this central channel are the injection pipes—six for gas fuelling, three for the neutral beam system. In both systems, process pipes are contained in a 25-centimetre (10-inch) guard pipe, in which the interspace is inerted by dry nitrogen gas. This nitrogen gas flows towards the tritium plant for leak detection. The gas fuelling manifold terminates at several gas valve boxes that control the flow rates of all gases, dosing them into the torus. Within the gas valve box will sit a gas flow controller that is not only fast, but that can also survive the radioactive environment. The Chinese Domestic Agency is developing its own gas flow controller, because nothing on the market meets the requirements for response time and compatibility with the harsh environment. Keeping safety involved The gas injection system has to meet the strict French regulations, with extra care for transporting radioactive and flammable gases. Any leaks from the process pipes will be detected by the counter flowing nitrogen, and carried back to the tritium plant, where leak detection mechanisms quickly raise alerts to allow a safe machine shut down. 'There is a pressure cascade from the room where manifolds are located, and process pipes to prevent gases are leaking out,' says Jordan. 'We actively keep the pressures at these levels—and if we detect any anomalies, we shut down the plasma.' 'Because the gas injection system is a PIC [protection important component] system, a big part of our work has been keeping safety fully involved. Like all of ITER we deal with tolerance and quality concerns in our materials and our craftsmanship. A lot of our work here in France has been to stay in close contact with our manufacturer and our Domestic Agencies, and to work hand-in-hand with them to maintain the highest standards.' All connections of the inner pipes in the gas injection system are full penetration welds, with special considerations being taken for welding—especially with the ITER grade stainless steels. Before shipping, all welds were radiographed as a required non-destructive test (NDT), and all the pipes were helium leak tested. To protect the manifolds during shipping, unique frames were custom built to support each spool. 'Just in case, we perform our own inspections after receiving the manifolds on site,' says Jordan. 'Our final checks involve high-tech measurements of some of the more complicated parts using metrology.' 'Not only do keep safety involved in all aspects of our work, from start to finish, but we also have a full-time quality engineer on our team—just to make sure we don't miss anything.' See a related video here.

Over the past five and a half years, dozens of heavy ITER components have been unloaded at Marseille industrial harbour to be transported along the ITER Itinerary as 'highly exceptional loads' to the ITER site. The record so far has belonged to the D-shaped toroidal field coils from Europe and Japan (360 tonnes each) that were delivered to ITER in April. But next week, as poloidal field #6 (PF6) leaves the shores of the inland sea Étang-de-Berre and begins its land journey to ITER, the record will be shattered. Procured by Europe, manufactured by ASIPP in Hefei, China, PF6 is one of the six ring magnets that circle the vacuum vessel of the ITER Tokamak. Sitting at the bottom of the machine, it is the second smallest (10.5 metres in diameter) and yet the heaviest (400 tonnes) of the six. Adding to the weight of the coil proper, the transport frame and trailer bring the total load close to 800 tonnes. However, the challenge of transporting this massive component over a distance of 100 kilometres is not so much its weight but its width. The transport frame for the circular coil is just over 11 metres wide, and a few passages along the ITER Itinerary had to be adapted for this component particularly. A narrow passage between two cliffs was enlarged in the summer of 2018, and the precise topography of a long tree-lined alley was captured by 360-degree 3D scanning in order to identify every single branch that could potentially stand in the way of the convoy, decide where to prune, and plot the best course for the trailer to slalom between obstacles. PF6, which was unloaded at Marseille harbour on 11 June, is scheduled to reach ITER before the end of this month. Since January 2015, when a 90-tonne, US-procured electrical transformer reached ITER, 86 'highly exceptional loads' have travelled the ITER Itinerary. Approximately 120 more are expected in the five years to come, including another 16 toroidal field coils and all nine 440-tonne vacuum vessel segments. Next in line for arrival are toroidal field coil #13 from Japan, and vacuum vessel sector #6 from Korea.

The message is one of collective pride. 'We have delivered' reads the large banner that is now affixed to the north wall of the Tokamak Building. Constructing this monumental edifice, whose shape and cladding are emblematic of the ITER Project was the work of close to 1,000 men and women. Under the responsibility of the European Domestic Agency, Fusion for Energy (F4E), and the joint ITER Organization/F4E Buildings Infrastructure and Power Supplies (BIPS) team, dozens of companies large and small brought together their experience, their creativity, and their dedication to realize this one-of-a-kind construction—the home of the ITER Tokamak, the largest fusion machine ever designed and the first that will generate net energy. For the Vinci Ferrovial Razel-Bec (VFR) consortium that led the effort, 'the banner is a testimony of more than eight years of hard work' that culminated on 16 March, two weeks ahead of the scheduled completion date and despite the stringent constraints that the COVID-19 pandemic already imposed on worksite activity. In its acknowledgment, the banner forgets none of the 1,000 men and women who had their part in this achievement. Whatever their trade, whatever the country they hailed from, they have contributed to writing history.

A wealth of information about the behaviour and stability of the ITER plasma will be communicated by the return signals of the low-field side reflectometer (LFSR)—a diagnostic that shoots a frequency-modulated (FM) millimetre wave signal (a type of microwave) into the plasma and gathers information about the plasma edge in return. The LFSR is the first device of its kind to measure the plasma density, and process and report the data to the central tokamak control system in real-time. This allows it to serve as an alert system, as abrupt changes in the steepness of the edge density profile, or gradient, can lead to instabilities known as edge localized modes (ELMs), which release large amounts of energy. A final design review is planned this summer by the US ITER diagnostics team, which is based out of the Princeton Plasma Physics Laboratory. The device will be installed on ITER before its First Plasma. See the original news on the US ITER website or this report from the Princeton Plasma Physics Laboratory.