Cryodistribution
Cold boxes 20 years in the making
27 Nov 2023
Twenty years—that is how long it took to design, manufacture and deliver the cold valve boxes that regulate the flow of cryogens to the tokamak's vacuum system. Last week, as the first of the eight first-of-a-kind components was undergoing site acceptance testing, the °ÄÃÅÁùºÏ²Ê¸ßÊÖ vacuum team organized a "pat on the back" moment to celebrate the completion of this unique conceptual and industrial adventure.
Robert Pearce (centre), Vacuum System Project Leader, gathers past and present actors of the 20-year cold valve box adventure for a "pat in the back" moment in the vacuum lab.
Procured by Europe, manufactured by (Germany) and its subcontractor (Netherlands), the eight cold valve boxes are 4-tonne components measuring more than 3 metres in height and approximately 2 metres in diameter. Each one is equipped with 25 cryogenic valves, relief systems, and pressure and temperature sensors that are specifically designed to operate under the harsh °ÄÃÅÁùºÏ²Ê¸ßÊÖ environment. Located in the lower port cells, six boxes are destined for the torus cryopumps and two for the cryostat.
Cold valve boxes are massive components designed to operate within an exceptionally large temperature range under the harsh magnetic and neutronic environment of the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Tokamak.
Preliminary design activities began in 2004 at the French Alternative Energies and Atomic Energy Commission (CEA), the procurement agreement was signed in 2017 with the European Domestic Agency Fusion for Energy, and a final design was achieved in 2020. Designing and manufacturing the complex components was particularly challenging, as they will be exposed to the intense magnetic field inside the machine and the high neutron flux from the fusion reaction. The cold valve boxes will operate within an exceptionally large temperature range: from 4K (minus 269 °C) when distributing supercritical helium to the cryopumps, to 200 °C when hot gas is blown into the boxes during the regeneration process.
The functional tests presently performed in the °ÄÃÅÁùºÏ²Ê¸ßÊÖ vacuum lab will be followed by cold tests at liquid nitrogen temperature (80K, minus 196 °C). An installation is being prepared in the cryoplant to test at 4K.