Limitations on blanket performance

The limitations on the performance of breeding blankets in a fusion power p lant are evaluated. The breeding blankets will be key components of a plant and their limitations with regard to power density, thermal efficiency and lifetime could determine to a large degree the attractiveness of a power p lant. The performance of two rather well known blanket concepts under devel opment in the frame of the European Blanket Programme is assessed and their limitations are compared with more advanced (and more speculative) concept s. An important issue is the question of which material (structure, breeder , multiplier, coatings) will limit the performance and what improvement wou ld be possible with a 'better' structural material. This evaluation is base d on the premise that the performance of the power plant will be limited by the blankets (including first wall) and not by other components, e.g. dive rters, or the plasma itself However, the justness of this premise remains t o be seen. It is shown that the different blanket concepts cover a large ra nge of allowable power densities and achievable thermal efficiencies, and i t is concluded that there is a high incentive to go for better performance in spite of possibly higher blanket cost. However, such high performance bl ankets are usually based on materials and technologies not yet developed an d there is a rather high risk that the development could fail. Therefore, i t is explained that a part of the development effort should be devoted to c oncepts where the materials and technologies are more or less in hand in or der to ensure that blankets for a DEMO reactor can be developed and tested in a given time frame. (C) 1999 Elsevier Science S.A. All rights reserved.