Page 249 - Fundamentals of Magnetic Thermonuclear Reactor Design

230 Fundamentals of Magnetic Thermonuclear Reactor Design

high-performance relatively cheap stainless steel—is used for the load-bearing
structures, collectors, attachment and welding elements.
A multilayer panel is more complex than a solid one and involves the prob-
lem of a reliable connection, but this is offset by the advantages of an efficient
utilisation of different materials’ properties and functions.
Generally, an engineering solution to creating a high-longevity nuclear power
system, such as the ITER, is difficult to make because of the scarcity or uncertain-
ty of initial technical information. Therefore, it has to be as variative as reasonably
possible and able to accommodate potential innovations. Engineering design ac-
tivities for ITER in-chamber components were initially based on these principles.
At the first stage of reactor operation, the vertical target is to be coated with
graphite or carbon fibre composite, CFC. These materials do not suffer from
melting and are highly resistant to cracking at maximum design stresses. Their
utilisation ensures the target’s efficient operation at the first stage and allows the
practical issues in thermal engineering to be better defined. If these issues appear
to be consistent with the use of the tungsten armour, then graphite/CFC will be re-
placed with tungsten before the D–T experimenting stage. We remember that the
said materials are unacceptable at that stage due to the tritium accumulation risk.
In addition, the need to optimise the structure and geometry of the entire
divertor assembly may emerge after the first experimental phase. This may in-
volve the adjustment of the divertor targets’ length and tilt angle and the in-
cassette vacuum duct cross section. The ITER project provides for the divertor
assembly adjustment and reconfiguration, as well as for a repeated replacement
of the limiter panels, involving material and configuration changes.

7.3.2 Component Modelling: Technological and Testing Facilities

A lot of joint experiments have been carried out on test benches and testing and
development facilities under the ITER First Wall R&D Programme in ITER mem-
ber countries. The most sizeable experimental facilities include the following:
l The SM-3 and RBT-6 reactors in Russia, used to study the effect of neutron
fluence and thermal cycling damages on EU and RF FW mockups.
l The JUDITH test facility in Germany, used for thermal mechanical experi-
ments with material samples and FW component mockups, fabricated in the
EU, Russia, the USA and Japan and subjected to pre-irradiation.
l The IDTF (Russia) electron beam test stand with a full electron beam power
of ∼0.8 MW, used for testing full-size models of targets from EU, Japan and
Russia.
l The VIKA and МК-200UG plasma accelerators (Russia), used to simulate
plasma current disruption heat loads.

An important part of the Programme is the ‘round-robin’ tests by interna-
tional experts of power and temperature measurement systems on test benches
in the EU, Russia, USA and Japan.