SELECTION CRITERIA FOR FUSION REACTOR STRUCTURES

Yıl 2019, Cilt: 5 Sayı: 2 - Issue Name: Special Issue 9: International Conference on Mechanical Engineering 2017, Istanbul, Turkey, 46 - 57, 29.01.2019

Sümer Şahin

https://doi.org/10.18186/thermal.531703

Cited By: 2

Öz

Fusion energy is the ultimate energy to cover Mankind’s energy needs
forever. However, taming the fusion energy is the greatest technological
challenge the humanity is facing. Development of structural materials to
withstand against the extreme conditions in the course of fusion power plant
operation is one of the toughest nuts to be cracked. A great number of
structural materials have been investigated for fusion reactor applications,
such as steels (austenitic stainless steels and ferritic/martensitic steels),
vanadium alloys, refractory metals and alloys (niobium alloys, tantalum alloys,
chromium and chromium alloys, molybdenum alloys, tungsten and tungsten alloys),
and composites (SiC_f/SiC and Carbon Fibre Composite CFC composites).

Steels have extensive technological data base and significantly
lower cost compared to other refractory metals and alloys. Ferritic steels and
modified austenitic stainless (Ni and Mo free) have relatively low residual
radioactivity. However, steels cannot withstand high neutron wall loads to
build an economically competitive fusion reactor. Some refractory metals and
alloys (niobium alloys, tantalum alloys, molybdenum alloys, tungsten and
tungsten alloys) can withstand high neutron wall loads. But, in addition to
their very limited technological data base, they have high residual
radioactivity and prohibitively high production costs.

A protective, flowing liquid
zone to protect the first wall of a fusion reactor from direct exposure to the
fusion reaction products could extend the lifetime of the first wall to the
expected lifetime of the fusion reactor. In that context, a fusion-fission (hybrid) with a multi-layered
spherical blanket has been investigated, which is composed of a first wall made
of oxide dispersed steel (ODS, 2 cm); neutron multiplier and coolant zone made
of LiPb; ODS-separator (2 cm); a molten salt FLIBE coolant and fission zone;
ODS-separator (2 cm); graphite reflector. Calculations are conducted for a liquid wall with variable thickness,
containing Flibe + heavy metal salt (UF₄ or ThF₄) is used
for first wall protection. The content of heavy metal salt is chosen as 4 and
12 mol%. A flowing wall with a thickness of ~ 60 cm can extend the lifetime of
the solid first wall structure to a plant lifetime of 30 years for 9Cr–2WVTa
and V–4Cr–4Ti, whereas the SiC_f/SiC composite as first wall needs a
flowing wall with a thickness of ~ 85 cm to maintain the radiation damage
limit.

Anahtar Kelimeler

Fusion Reactors, Structural Materials, Refractory Metals, Molten Salt, First Wall, Radiation Damage

Kaynakça

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