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The vanadium—lithium test facility has been constructed to carry out corrosion tests of vanadium alloys in lithium flow, to evaluate the welding procedures and to develop electrically insulating coatings for lithium self-cooled blanket application. The corrosion tests were performed in a nonisothermal lithium flow with the flow rate up to 1 m/s at temperatures in the range 450–700°C. The results of development of the electricity insulating coatings are presented. The achieved specific resistance of AlN based coatings is 30–40 Ω m. The results of electron-beam and argon tungsten-arc welding methods are presented for welding sheets, rods and pipes for V-Ti-Cr type alloys. Solution of the vanadium alloys and vanadium alloys—stainless steels welding problems enabled construction of a liquid metal system satisfying all the necessary requirements.

Vanadium-based alloys are most promising as low activation structural materials for DEMO. It was previously established that high priority is to be given to V-alloys of the V-Ti-Cr system as structural materials of a tritium breeding blanket and the first wall of a fusion reactor. However, there is some uncertainty in selecting a specific element ratio between the alloy components in this system. This is primarily explained by the fact that the properties of V-alloys are dictated not only by the ratio between the main alloying elements (here Ti and Cr), but also by impurities, both metallic and oxygen interstitials. Based on a number of papers today one can say that V-Ti-Cr alloys with insignificant variations in the contents of the main constituents within 5–10 mass% Ti and 4–6 mass% Cr must be taken as a base for subsequent optimization of chemical composition and thermomechanical working. However, the database is obviously insufficient to assess the ecological acceptability (activation), physical and mechanical properties, corrosion and irradiation resistance and, particularly, the commercial production of alloys. Therefore, there is a need for comprehensive studies of promising V-alloys, namely V-4Ti-4Cr and V-10Ti-5Cr.

Experimental models of capillary structure for liquid metal fusion reactor divertor simulation have been designed, manufactured and tested in order to estimate the behaviour and possibilities of plasma-facing components based on lithium capillary system at long-pulse high heat load. The power load on the capillary target structures up to 50 MW/m2was provided by electron beam with electron energy ≤ 10 keV. The exposition-time was up to several minutes and was limited by the lithium quantity in the supply vessel. The operation parameters of the models determined in the experiments are in accordance with there design estimations. The tests of various model constructions at the divertor relevant power loads have shown promise for the new concept of a divertor taking into account long life and reliability.

The absence of a satisfactorily developed fusion reactor (FR) divertor approach (having no lost layers of sputtered plate materials and/or replaceable blocks) has become the reason for the development of the new concept of liquid-metal divertor (LMD) with a capillary-pore (CP) lithium protection system. Creative and novel design and material solutions, combined with unique natural thermophysical properties of Li working in a gas target evaporation—radiation mode, ensures the prolonged and steady performance of a FR divertor (D).

The reliable information on design and material properties of self-cooled LiLi blanket and liquid metal divertor under neutron radiation conditions can be obtained using the concept of combined technological and material in-pile tests in a vanadium—lithium loop. The method of in-pile loop tests includes studies of vanadium—base alloys resistance, weld resistance under mechanical stress, multipurpose coating formation processes and coatings' resistance under the following conditions: high temperature (600–700°C), lithium velocities up to 10 m/s, lithium with controlled concentration of impurities and technological additions, a neutron load of 0.4–0.5 MW/m2and level of irradiation doses up to 5 dpa. The design of such an in-pile loop is considered. The experimental data on corrosion and compatibility with lithium, mechanical properties and welding technology of the vanadium alloys, methods of coatings formation and its radiation tests in lithium environment in the BOR-60 reactor (fast neutron fluence up to 1026m−2, irradiation temperature range of 500–523°C) are presented and analyzed as a basis for such loop development.