Elimination of the coil shielding for mfe-reactors through a liquid-protected first-wall

الملخص EN

The idea of a protective, flowing, liquid zone to protect the first wall of a magnetic fusion energy (MFE) reactor from the direct exposure of the fusion reaction products is not new.

This could extend the lifetime of the first wall to the lifetime of the fusion power plant, namely to 30 years.

The present work discusses the possibility that such a liquid zone could lead also to the elimination of the magnetic coil shielding for MFE reactors.

Contrary to a related previous work, the liquid wall is now placed at the outermost periphery of the plasma chamber, in order to leave a greater space for the fusion plasma volume and consequently to lead to higher fusion power with the same plasma parameters.

In this work, SS-304 type steel, SiC, and graphite are selected as structural materials.

Different types of liquid coolant with tritium breeding capabilities (Flibe, Li17Pb83, natural lithium, all with natural lithium component) are investigated to protect the first wall from neutron- and bremsstrahlung-radiation and fusion reaction debris.

The calculations are conducted for a power generation of 1 GWel over 30 years of reactor operation with a thermodynamically conversion efficiency of 35 % leading to 2.857 GWth by a capacity factor of 100 %.

The most important improvements through the placement of the protective liquid wall at the outer periphery in the new blanket can be cited as follows.

Such a blanket: • would in practice not necessitate extra shielding for superconducting coils around the fusion plasma chamber; • would open the possibility of utilization of conventional stainless steel for fusion reactors due to the sufficiently low residual radioactivity in the structural materials after decommissioning of the plant.

Research efforts and costs, involved in searching new alternative ceramic structural materials, such as SiC and graphite, based on unproven technology can be saved; • and would make it possible to produce higher fusion power with a greater plasma volume