Assessment of the gas dynamic trap mirror facility as intense neutron source for fusion material test irradiations

The gas dynamic trap (GDT) mirror machine has been proposed by the Budker I nstitute of nuclear physics, Novosibirsk, as a volumetric neutron source fo r fusion material test irradiations. On the basis of the GDT plasma confine ment concept, 14 MeV neutrons are generated at high production rates in the two end sections of the axially symmetrical central mirror cell, serving a s suitable irradiation test regions. Tn this paper, we present an assessmen t of the GDT as intense neutron source for fusion material test irradiation s. This includes comparisons to irradiation conditions in fusion reactor sy stems (ITER, Demo) and the International Fusion Material Irradiation Facili ty (IFMIF), as well as a conceptual design for a helium-cooled tubular test assembly elaborated for the largest of the two test zones taking proper ac count of neutronics, thermal-hydraulic and mechanical aspects. This tubular test assembly incorporates ten rigs of about 200 cm length used for insert ing instrumented test capsules with miniaturized specimens taking advantage of the 'small specimen test technology'. The proposed design allows indivi dual temperatures in each of the rigs, and active heating systems inside th e capsules ensures specimen temperature stability even during beam-off peri ods. The major concern is about the maximum achievable dpa accumulation of less than 15 dpa per full power year on the basis of the present design par ameters of the GDT neutron source. A design upgrading is proposed to allow for higher neutron wall loadings in the material test regions. (C) 2000 Els evier Science S.A. All rights reserved.