Conceptual design studies for the European DEMO divertor: Rationale and first results

Abstract

In the European fusion roadmap, reliable power handling has been defined as one of the most criticalchallenges for realizing a commercially viable fusion power. In this context, the divertor is the key in-vessel component, as it is responsible for power exhaust and impurity removal for which divertor targetis subjected to very high heat flux loads. To this end, an integrated R&D project was launched in theEUROfusion Consortium in order to deliver a holistic conceptual design solution together with the coretechnologies for the entire divertor system of a DEMO reactor. The work package ‘Divertor’ consistsof two project areas: ‘Cassette design and integration’ and ‘Target development’. The essential missionof the project is to develop and verify advanced design concepts and the required technologies for adivertor system being capable of meeting the physical and system requirements defined for the next-generation European DEMO reactor. In this contribution, a brief overview is presented of the works fromthe first project year (2014). Focus is put on the loads specification, design boundary conditions, materialsrequirements, design approaches, and R&D strategy. Initial ideas and first estimates are presented

Improved fracture behavior and microstructural characterization of thin tungsten foils

“…The preparation procedure can be summed in the following three steps: The test specimens were fabricated out of the commercially available tungsten sheet with dimensions of 180 × 100 × 0.1mm 3 with the rolling direction being parallel to the 100 mm side of the sheet. Electrical discharge machining (EDM) was used for cutting and the specimen size is 20 × 5 × 0.1mm 3 . In order to examine the influence of the microstructure on the anisotropy of mechanical properties, it is important to know the direction of cutting in respect to the rolling direction of the sheet i.e.…”

“…in a future fusion reactor. Extensive research on divertor design concepts is directed towards the use of various tungsten materials and its composites for different divertor applications, making tungsten one of the main armour and heat sink materials candidates [1,2] . A divertor is one of the key in -vessel components of a fusion reactor, responsible for power exhaust and cleaning the plasma from He and impurities i.e.…”

“…loads: in a normal scenario 10 MW/m 2 is expected, having peaks of up to 20 MW/m 2 in off normal events, as a consequence of different plasma instabilities [3,4] . For such a challenging and extreme thermal application, tungsten was a natural choice as a candidate material.…”

Structural analysis of DEMO divertor cassette body and design study based on RCC-MRx

“…The present paper reports the latest progress in the structural design study for the European DEMO divertor cassette body which has been conducted in the framework of the work package "Divertor" of the EUROfusion Consortium [1][2][3][4][5]. The structural design study serves as one of the major elements of preconceptual design of DEMO divertor cassette.…”

Engineering challenges for accelerated fusion demonstrators

“…Both components are subject to plasma erosion but this is mitigated in the divertor by the use of a thick (approx. 50 mm) mono-block of tungsten [8], a solution derived from the ITER design and shown in figure 1, but because the ITER first wall is beryllium and has no breeding blanket behind it, its design is not applicable to the first wall protection panels, or indeed any of the first wall structure.…”