J.B.J. Hegeman

Thermomechanical behaviour of ceramic breeder pebble stacks for HICU

This paper reports on the thermomechanical behaviour of small pebble beds or pebble stacks in order to lay out irradiation test specimens. Uniaxial compression tests (UCTs) of the pebble stacks with relatively small diameters are performed at 27 and 800 °C i.e. the maximum irradiation temperature. The H/D ratio of the specimens influences the thermomechanical behaviour because of the friction between the pebbles and the steel tube. The results are compared with the thermomechanical data obtained from standard UCTs, which apply for larger pebble-beds. The outcome of the comparison will be used for the detailed design of the constrained pebble-beds in the high fluence irradiation. In addition, the compatibility between the ceramic breeder materials and the containment is studied. It has been shown that platinum has the best compatibility at 800 °C for both the lithium meta-titanate and lithium ortho-silicate ceramics.

Irradiation of SiCf/SiC composites, fibres and matrices in HFR Petten

Abstract This paper reports on the pre-irradiation tests of SiC f /SiC materials as a contribution to the EFDA Technology Programme on advanced materials. A high temperature irradiation of SiC materials in the High flux Reactor in Petten, denoted as ‘SICCROWD’ has recently started. The SiC f /SiC materials included are supplied by the EU partners. Further materials are included in the frame of an IEA collaborative effort, by Japanese and USA partners. The irradiation matrix comprises a variety of fibres and matrix materials, as well as composites with 1-D, 2-D or 3-D architectures. CVD monolithic SiC serves as a reference material and should enable comparison with other, e.g. complementary, irradiation data. The specimen types are bars, for four-point bend tests, and discs for flash diffusivity measurements. Both types will be used to measure dimensional changes. Some specimens have been mounted to allow for in-situ determination of thermal conductivity degradation by neutron irradiation. The irradiation rig, materials and test matrix will be presented as well as the results of the pre-irradiation characterisations.

Irradiation Testing of Blanket Materials at the HFR Petten with On Line Tritium Monitoring

Irradiation experiments are performed in support of fusion blanket technology development. These comprise ceramic solid breeder materials, and a liquid Lithium Lead alloy, as well as blanket subassemblies and components. Experimental facilities at the HFR to study tritium release, permeation characteristics, and neutron irradiation performance, have recently been extended. This paper gives an overview on the tritium breeding materials irradiation programme and describes the facilities required for irradiation testing and on-line tritium measurement.