One of the main ITER goals is to test and validate design concepts of tritium breeding blankets relevant to DEMO or fusion power plants. To achieve this goal, the development of Test Blanket Module (TBM) based on the corresponding DEMO or fusion power reactors is required, despite of the differences in operating conditions from ITER. Various design concepts of TBMs proposed by the ITER Parties will be installed and tested in the two ITER Equatorial Ports (16 and 18)
The tests foreseen on TBM include the demonstration of a breeding capability that would lead to tritium self-sufficiency in a reactor and the extraction of high-grade heat suitable for electricity generation.
Necessity of the development
The TBM program is the first test under the D-T fusion reaction on breeding blankets to validate their design concepts. The results obtained from the program may not be shared among the ITER Parties, unlike other procurement packages, since it was not included in the Joint Implementation Agreement (JIA) of ITER. Therefore, taking into account that blankets with the tritium self-sufficiency are critical to realize fusion power plants, Korea is willing to take important role in the TBM program to lead future fusion technology.
Current status of the development
Korea has been proposed two TBM concepts. One is a Helium Cooled Solid Breeder (HCSB) TBM applicable to a near-term breeding blankets, and the other is a Helium Cooled Molten Lithium (HCML) applicable to a long-term breeding blankets. The main features of the concepts are as belows.
- RAFM(Reduced Activation Ferritic / Martensitic) steel woth Be armor as a structural material
- 8 MPa He as a coolant
- Lithium ceramic(Li4SO4 or Li2Tio3) pebble as a tritium breeder
- Be pebble as a neutron multiplier
- Graphite pebble as a neutron reflector which reduces the amount of Be considerably
- RAFM steel with Be armor as a structural material
- 8 MPa He as a coolant
- Liquid lithium(natural or slight enrichment like 8~10&)as a tritium breeder
- Graphite neutron-reflector for replace Be multiplier(Be-free concept)
As of now, due to the limited space for testing all TBMs proposed by ITER Parties, the TBM consortiums with a concept leader and partners are envisaged. Principles for the selection of leading Party including the legal framework, cost sharing and the program schedules are to be agreed among ITER Parties within the consortium.
As one of the components exposed to the most severe condition in ITER such as high neutron irradiation, surface heat flux, temperature and magnetic field, various design technologies with neutronics, thermo-hydraulics, thermo-mechanics, safety analysis, etc are required to develop TBMs. This would give a valuable opportunity not only to validate the design tools and database under fusion environment but also to secure technologies required for developing breeding blankets.