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An intense source of 37 Ar was produced by the (n, α) reaction on 40 Ca by irradiating 330 kg of calcium oxide in the fast neutron breeder reactor at Zarechny, Russia. The 37 Ar was released from the solid target by dissolution in acid, collected from this solution, purified, sealed into a small source, and brought to the Baksan Neutrino Observatory where it was used to irradiate 13 tonnes of gallium metal in the Russian-American gallium solar neutrino experiment SAGE. Ten exposures of the gallium to the source, whose initial strength was 409 ± 2 kCi, were carried out during the period April to September 2004. The 71 Ge produced by the reaction 71 Ga(ν e , e − ) 71 Ge was extracted, purified, and counted. The measured production rate was 11.0 +1.0 −0.9 (stat) ± 0.6 (syst) atoms of 71 Ge/d, which is 0.79 +0.09 −0.10 of the theoretically calculated production rate. When all neutrino source experiments with gallium are considered together, there is an indication the theoretical cross section has been overestimated.

Recent progress in the RF low activation structural materials R&D road map towards DEMO via the FBR tests (BOR-60, BN-600, BN-800) and the TBM tests in ITER is overviewed. The properties of the RAFMS RUSFER-EK-181 (Fe-12Cr-2W-Ta-V-B-C) and the V-4Ti-4Cr alloys are presented. The next important steps include further studies on the influence of high dose and high-temperature irradiation on the properties of base structural materials and joints. Activation, transmutation and radiation damage of the materials in BN-600 and DEMO-RF (Kurchatov Institute project) neutron spectra are calculated. The results of the application of the internal friction (ultrasonic) non-destructive method to research the DBTT are in good agreement with the results of the destructive impact method. The important influence of boron on the heat resistance of materials and the He concentration level under irradiation are calculated. The new special regimes of the heat treatments of the alloys are suggested to widen the temperature windows of the applications. The results of the BOR-60 examinations of RUSFER-EK-181 (irradiation temperature 320-340 • C and doses up to 15 dpa) are presented. The BN-600 projects for the high dose and high-temperature irradiation tests of manufactured alloys are presented.

The status of work on the development of a 1200 MW sodium-cooled reactor facility for serial construction is presented. The general characteristics of the facility and the power-generating unit as well as the objectives which must be attained as a result of the design are presented. The design of the power-generating group is based on solutions some of which have been checked during the operation of sodium-cooled reactors in Russia and some have been validated by the appropriate research and development work performed for BN-800. At the same time, new solutions are used which are aimed at improving the technical-economic indicators and increasing the level of safety. Additional R&D work will be needed to validate them.The nuclear future of Russia and most other countries developing nuclear power involves fast reactors and a closed fuel cycle. Thus far only sodium-cooled fast reactors are ready for commercial adoption on a wide scale. In our country, we have more than 50 years of experience in developing and successfully operating such reactors: BR-5 (1959) → BR-10 (1973-2002) → BOR-60 (1969 -in operation) → BN-350 (1973-1998) → BN-600 (1980 -in operation) → BN-800 (under construction). A design of an advanced power-generating unit with a sodium-cooled BN-1200 reactor as the foundation for the initial step in the serial construction of reactors of this type is under development.Target Indicators of Reactor Facility and Power-Generating Unit Design. The development of a power-generating unit must meet the following requirements set for new-generation reactors and nuclear power plants:1) competitiveness with advanced power-generating unit based on reactors of a different type and power-generating units operating on fossil fuel;2) safety increased to a level that makes it unnecessary to take measures to protect the general public outside the borders of the nuclear power plant site for any possible accidents;3) attainment of breeding ratios from 1.2 (stage 1) to 1.3-1.35 (stage 2) using mixed oxide fuel and 1.45 with nitride fuel; 4) reducing the construction time for serially built power-generating units to 48 months; and 5) possibility of introducing a series of reactors in 2-3 years after the startup of the main power-generating unit.

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