ITER Cryostat—An overview and design progress

The ITER Cryostat is one of the most important and critical systems in the ITER project. It envelops the entire basic systems of the Tokamak and is a vacuum tight container. Cryostat provides vacuum environment for the thermal insulation to magnet system operating at 4.5k and thermal shield system operating at 80k. It is evacuated to a pressure of 10−4 Pa prior to cool down of the magnets and thermal shields in order to limit heat transfer by gas conduction and convection to a level tolerable to the cryogenically cooled components. The cryostat is also designed to support all the loads like gravity, electromagnetic forces, seismic, etc. that derive from the Tokamak basic systems, and from the Cryostat itself, to the floor of the Tokamak pit through its support structures during the normal and off-normal operational regimes, and at specified accidental conditions. ITER Cryostat conceptual design was reviewed last year and detailed design is reviewed in June 2010. At present Cryostat design is in its final stage of completion and final design review is planned in October 2010 to finalize the procurement specifications. Procurement Arrangement will be signed this year with Indian Domestic Agency and procurement cycle will start for the fabrication of the ITER Cryostat. This paper discusses the updated Cryostat design and analysis with integration of the different penetrations required for the communication within the In-Cryostat system and its maintenance.