Page 343 - Fundamentals of Magnetic Thermonuclear Reactor Design

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Liquid breeding materials:
l Ensuring compatibility with structural materials.
l Breeding process research and development of relevant databases.
l Adjustment of optimised tritium extraction processes, and identification of
relevant operating temperature ranges.
Coolants:
l Ensuring compatibility with structural materials.
l Adjustment of processes for maintaining required coolant content and re-
moving impurities, undesirable in terms of activation and corrosive effects.
l Development of heat-to-electricity conversion systems based on conven-
tional energy processes.
Protective barriers:

l Development of electrically insulating barriers to coat the walls of liquid-met-
al ducts in blankets. These barriers should significantly reduce MHD pressure
losses by decreasing electric currents generated by moving a metal through a
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magnetic field. They must satisfy requirement ρδ > 0.02 Ωm , where ρ is the
protective coating’s specific electrical resistance (Ω m), and δ is its thickness
(m). Self-healing barriers are most attractive candidates. They result from a
chemical interaction of a liquid metal’s individual components with a structur-
al material’s ingredients. An alternative is a thin electrically conducting film
separated from the duct by an electrically insulating layer.
l Development of anti-corrosion barriers at the duct wall–liquid metal inter-
face, especially important for the Pb–Li coolant. In some cases, wall cor-
rosion rate should be decreased by an order of magnitude and its tritium
permeability, by 2–3 orders of magnitude.
l Development of tritium barriers on the liquid metal side or on the structure’s
outboard side, as well as tritium barriers for the tritium circuit pipes.
l Experimental validation of the barriers’ operability at design temperatures,
fast neutron fluence and expected durability.
Radiation and environmental safety:
l Mitigation of operation risks and hazards associated with the chemical in-
teraction of reactor materials (lithium or Pb–Li eutectic alloy with water
and air, beryllium with water vapour, etc.) in off-normal situations to levels
considered safe by socio-economic criteria.
l Prevention of tritium’s uncontrolled release from structural materials,
beryllium, breeding materials and coolants in off-normal situations.
l Decrease in residual heat production and radioactive product release in
hypothetic off-normal situations to environmentally safe levels.
l Decrease in residual activation of materials to levels considered safe for
their processing or shallow land burial.