Page 73 - Fundamentals of Magnetic Thermonuclear Reactor Design

56 Fundamentals of Magnetic Thermonuclear Reactor Design

FIGURE 3.15 The energy receiver’s cassette. (Copyright ITER Organization, 2017).

more resistive to heavy thermal loads and offer high heat conductivity. A purely
tungsten cover is also considered as a candidate material. Turbulent water flow
pumped through the first contour cools the target plates. The divertor cassettes
and blanket modules surrounding a plasma column also act as a neutron flux
shield for the magnetic system.
For maintenance/repair, the divertor cassettes are removed from the vessel
using one of the three access ports. A cassette is moved to the access port by a
rail on the vessel floor. The rails are also used to anchor the divertor cassettes
during assembly operations.

3.6 THERMAL SHIELDS

The reactor structural components operate under different thermal and physical
conditions. The temperature of the VV’s outer surface ranges from 70 to 200°C
depending on the operation mode. The temperature of the cryostat surface is
slightly below the ambient temperature. The magnetic system, located between
the VV and the cryostat vessel, is maintained at 4.5 K. The inner and outer ther-
mal shields (Fig. 3.16) separate the VV, MS and cryostat shell to attenuate the
radiant flux onto the superconducting coils.
The shields, fabricated out of a thin, non-magnetic stainless-steel sheet, are
conformal with the VV and the cryostat shell. The thermal shields are kept at