Investigation of ITER candidate beryllium grades irradiated at high temperature

Beryllium is one of the main candidate materials both for the neutron multi plier in a solid breeding blanket and for the plasma facing components. Tha t is why the investigation of beryllium behaviour under the typical for fus ion reactor loading, in particular under the neutron irradiation, is of a g reat importance. This paper presents some results of investigation of five beryllium grades (DshG-200, TR-30, TshG-56, TRR, TE-30, TIP-30) fabricated by VNIINM, Russia, and one (S-65) fabricated by Brush Wellman, USA. The ave rage grain size of the investigated beryllium grades varied from 8 to 40 mu m, beryllium oxide content was 0.7-3.2 wt.%, initial tensile strength 250- 680 MPa. All the samples were irradiated in active zone of SM-3 reactor of 650-700 degrees C up to the fast neutron fluence (5.5-6.2) x 10(21) cm(-2) (2.7-3.0 dpa, helium content up to 1150 appm), E > 0.1 MeV. Irradiation swe lling of the materials was revealed to be in the range of 0.3-1.7%. Berylli um grades TR-30 and TRR having the smallest grain size and highest berylliu m oxide content, demonstrated minimal swelling, which did not exceed 0.3% a t 700 degrees C and fluence 5.5 x 10(21) cm(-2). Mechanical properties and microstructure parameters measured before and after irradiation are also pr esented. (C) 1998 Elsevier Science B.V. All rights reserved.