Flat Tile Armour Cooled by Hypervapotron Tube: a Possible Technology for ITER

High heat flux testing of plasma facing materials and components – Status and perspectives for ITER related activities

“…In particular for water cooled divertor targets in next step fusion reactors the heat removal limitations due to critical heat fluxes (CHF) have to be thoroughly determined to avoid unanticipated material damage. This phenomenon has been investigated carefully for a number of different coolant channel geometries such as the circular cross-sections with swirl tube inserts, the hypervapotron with coolant fins perpendicular to the coolant flow [10], and a screw-type coolant channel [11]. At high flow rates CTF values of 40 MW m À2 and beyond have been achieved; these data provide satisfactory safety margins against burn-out failure.…”

Technologies for ITER divertor vertical target plasma facing components

“…The main results on CFC monoblock large mock-ups are given in table 4 (note that several of these mockups have also a W part). Using the NB31 CFC from Snecma-Bordeaux (France) up to 2000 cycles at 20 MW m −2 were sustained [12,13]. In general, the CFC monoblock quality improved during the mock-up manufacturing contract, but cracks continued to be observed at the top of the CFC/Cu interface due to the shrinkage of the tube during the joiningprocess cooling-down.…”

“…This change in the cooling scheme resulted in a substantial improvement in the fatigue performances that exceed the ITER requirements. As a result this solution could constitute a possible fallback solution to the present reference design (figure 5) [12]. Moreover, this technology proved to be able to sustain under 10 MW m −2 the loss of a tile without cascade failure effect [18].…”

One-step brazing process for CFC monoblock joints and mechanical testing

“…The monoblock is preferred over the easier to manufacture flat tile design, because of the better heat flux performances and because of the observed tendency for flat tiles to suddenly and totally detach in high heat flux conditions [6].…”

“…[6] and attention should be given to solutions that mitigate or avoid the failures of armour/heat sink joints, for instance using lower manufacturing temperature.…”