| AVS 66th International Symposium & Exhibition | |
| Vacuum Technology Division | Tuesday Sessions |
| Session VT-TuA |
| Session: | Advanced Applications of Vacuum Technology |
| Presenter: | Charles Smith, Us Iter |
| Correspondent: | Click to Email |
This paper gives an overview of the ITER Tokamak Vacuum Auxiliary System (VAS) with a focus on the design challenges, solutions, and validation unique to a reactor-scale fusion vacuum system.
US ITER, the United States Domestic Agency for US contributions to the ITER project, is responsible for the final design, procurement, and acceptance testing for the Vacuum Auxiliary System (VAS) to be used in support of over 5000 clients of the ITER machine. The VAS system consists of more than six kilometers of pipework used in the vacuum roughing headers, more than 100 high-vacuum stations to support specific plant needs, and the Service Vacuum System (SVS) which is used to connect the roughing system to the end-use clients. VAS is a key element to the world’s first vacuum system rated for a licensed nuclear fusion facility.
ITER received a nuclear construction authorization decree from the French Ministry of Environment in 2012, as its goal is to demonstrate the feasibility of fusion energy and produce a reactor-scale deuterium/tritium fueled plasma. ITER’s VAS will utilize ASME B31.3 piping with a minimum schedule 10 wall thickness. In most large vacuum systems, commercially available vacuum fittings, flanges, and other standard components are designed around tubing. The requirement for schedule 10 piping and B31.3 design criteria has resulted in US ITER designing and certifying the components as opposed to procuring commercial off-the-shelf (COTS) items. These components must then be integrated into the overall VAS system in a way that meets all seismic and safety requirements needed to maintain tritium confinement. In addition to developing safety-critical double-gasket vacuum flanges, the certification of standard CF flanges to B31.3 has been required.
The VAS system’s interfaces and location through the tokamak building have created another set of challenges to the use of standard vacuum equipment. The tokamak building will be subjected to radiation and high magnetic fields during plasma operations. The proximity of vacuum systems to high power RF systems and tritium containment are all design inputs for VAS design. The SVS portion of VAS, in addition to its role of interfacing between clients and the roughing header, acts as an integral part of plant safety systems. The interspaces between the gaskets on safety related flanges are actively monitored by SVS to detect any change in pressure which could indicate a leak. As an example, the SVS is used to verify the integrity of diamond vacuum windows used in high-powered RF plasma heating systems.
The work detailed in this paper, shall illustrate the progress being made to reach the first plasma milestone.