E. Visca

Non-Destructive Testing of Divertor Components

This task within the EU RD (2) blind non-destructive round robin test of the prototype; (3) HHF test in FE200 electron beam (EB) facility; (4) post-fatigue blind non-destructive round robin test; (5) destructive examination. The general final conclusion was that the NDT techniques can reliably detect and locate defects having dimensions well below those, which could impair the thermal fatigue lifetime.

Status of fabrication development for plasma facing components in the EU

This paper summarises the European R&D efforts for the manufacture of shield modules and divertor cassettes for the International Thermonuclear Experimental Reactor (ITER), including their plasma facing components. The various development steps are described as they had to be taken to resolve the fabrication issues, and to keep track with the evolving design requirements and solutions. For all components, the manufacturing feasibility has been demonstrated on prototype scale which puts Europe in the position to start the procurement as soon as the decision about ITER construction is taken. The time period remaining until then is used to optimise the fabrication processes and to develop more cost effective alternatives.

European achievements for ITER high heat flux components

This paper summarises the main activities carried out by the EU Home Team to develop suitable solutions for the ITER high heat flux components, namely the divertor, the baffle and the limiter. The available results demonstrate that the EU have the capability to manufacture high heat flux components with carbon fibre reinforced carbon, tungsten and beryllium armours which all exceed the ITER design requirements.

Overview of the EU Small Scale Mock-up Tests for ITER High Heat Flux Components

Abstract This task within the EU R&D for ITER was aimed at the development of basic manufacturing solutions for the high heat flux plasma facing components such as the divertor targets, the baffles and limiters. More than 50 representative small-scale mock-ups have been manufactured with beryllium, carbon and tungsten armour using various joining technologies. High heat flux testing of 20 of these mock-ups showed the carbon mono-blocks to be the most robust solution, surviving 2000 cycles at absorbed heat fluxes of up to 24 MW m−2. With flat armour tiles rapid joint failures occurred at 5–16 MW m−2 depending on joining technology and armour material. These test results serve as a basis for the selection of manufacturing options and materials for the prototypes now being ordered.

Thermal Fatigue Tests with Actively Cooled Divertor Mock-ups for ITER

Abstract Mock-ups for high heat flux components with beryllium and CFC armour materials have been tested by means of the electron beam facility JUDITH. The experiments concerned screening tests to evaluate heat removal efficiency and thermal fatigue tests. CFC monoblocks attached to DS-Cu (Glidcop Al25) and CuCrZr tubes by active metal casting and Ti brazing showed the best thermal fatigue behaviour. They survived more than 1000 cycles at heat loads up to 25 MW m−2 without any indication of failure. Operational limits are given only by the surface temperature on the CFC tiles. Most of the beryllium mock-ups were of the flat tile type. Joining techniques were brazing, hot isostatic pressing (HIP) and diffusion bonding. HIPed and diffusion bonded Be/Cu modules have not yet reached the standards for application in high heat flux components. The limit of this production method is reached for heat loads of approximately 5 MW m−2. Brazing with and without silver seems to be a more robust solution. A flat tile mock-up with CuMnSnCe braze was loaded at 5.4 MW m−2 for 1000 cycles without damage. The first test with a beryllium monoblock joined to a CuCrZr tube by means of Incusil brazing shows promising results; it survived 1000 cycles at 4.5 MW m−2 without failure.

Acceptance tests of iter vertical target divertor full scale plasma facing units fabricated by HRP

ENEA and Ansaldo Nucleare S.p.A. (ANN) have being deeply involved in the European International Thermonuclear Experimental Reactor (ITER) development activities for the manufacturing of the inner vertical target (IVT) plasma-facing components of the ITER divertor. During normal operation the heat flux deposited on the bottom segment of divertor is 5-10 MW/m2 but the capability to remove up to 20 MW/m2 during transient events of 10 seconds must also be demonstrated. This component has to be manufactured by using armour and cooling pipe materials defined by ITER. The physical properties of these materials prevent the use of standard joining techniques. In order to overcome this difficulty, ENEA has set up and widely tested a manufacturing process, titled Hot Radial Pressing (HRP), suitable for the construction of these components. The last challenge is now to fabricate, by means the new HRP facility, a full scale prototype of the IVT for the final qualification and ENEA-ANN are now involved in the F4E-OPE138 contract where the fabrication of this component. The tolerances and acceptance criteria of the IVT plasma facing units (PFU) are fixed by ITER/F4E and are very tight. The objective of manufacturing a PFU that satisfies these requirements is an ambitious target. The final acceptance control to check the component compliance with the acceptance criteria is performed by ultrasonic water gap technique. A new equipment suitable for the final control of PFUs by ultrasonic was developed in ENEA with the purpose of speeding up the testing whilst mantaining the required technique resolution.

Experience and lessons from the JET 4.0 T assessment

Raising the JET maximum toroidal field from 3.45 to 4.0 T results in increased forces and stresses in the key machine components during normal operations and disruptions. These forces and stresses have been predicted for 4.0 T operation and compared with allowable values derived from tests on used and spare JET coils. In this assessment significant lessons related to the design, manufacture and operation of key Tokamak components have also been learnt.