The objective of WP 10 of this project is the development of the Breeding Blanket (BB) System for DEMO, including the Breeding Blanket sectors (BBS) and the associated Tritium Extraction/Removal system. The specific steps to reach this objective during the Conceptual Design phase are:
• Concept selection studies for Driver and DEMO Test Blanket Selection (2021-2024). The Helium-Cooled Pebble Bed (HCPB) and Water-Cooled Lithium Lead (WCLL) concepts will be further investigated, critical R&D completed and integration aspects clarified in relation to the possible DEMO plant architecture. This will provide a sound basis for the selection of a driver and advanced breeding blanket at G2.
• Validation of the BB system for the CD of DEMO (2025-27).
• Supporting R&D programme to validate the proposed design performance and increase the technical maturity level. This applies to critical technologies such as T-permeation/corrosion barriers, tritium extraction methods, fabrication and qualification of breeder and multiplier materials, and development and validation of alternative lower cost routes of fabrication for structural elements of the BB.
• Support the ITER TBM (Test Blanket Module) programme in preparation of the preliminary (2022) and final (2025) design reviews, as well as the procurement phase for the first TBM (2026-2027). WPBB will carry out the R&D programme jointly for DEMO and TBM in key topics of the ITER TBS (Test Blanket System) development both for the WCLL and HCPB TBM. It will support the breeders and neutron multipliers procurement of the first TBM set.
PbLi is not a standard alloy to be procured on the market, in particular if specific composition constrains are envisaged. Approaching the TBM manufacturing phase it is necessary to identify a reference production technique and one or more manufacturer available, to provide on time the necessary quantities of PbLi alloy with the required content of the 6Li isotope.
The main target of task “Activities related to the procurement of PbLi for the first TBM” (BB.TBM.T.02.01.T001) is to define a roadmap to secure the delivery of PbLi for the WCLL-TBS and then for DEMO. A production line for the WCLL-TBS phase should be prepared, with the possibility to update it to follow DEMO needs.
The activity will be developed as follow:
• A preliminary step is the definition of quality control for PbLi production: it is necessary to establish a quality procedure for the PbLi production, including parameters to be checked and reference techniques (each batch should be tested to ensure the quality/standardisation of the production).
• The “nuclear grade” specification should be addressed and defined, considering in particular the Li6 content and the relevant impurities to be specifically controlled to reduce activation issues. A reference production technique, at laboratory scale, will be identified.
• Li6 enrichment aspects shall be addressed, in particular, (i) a suitable chemical compound(s) to be used in the PbLi alloy production, and (ii) its regulatory (dual-use) and legal aspects. The goal should be to make sure that the issue of Li6 enrichment will not be a showstopper for the PbLi procurement and delivery for ITER-TBM and later on for DEMO.