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Information is presented on the development of the main equipment of the BN-1200 advanced reactor facility: first- and second-loop main circulation pumps, intermediate heat exchanger, actuation mechanism of the cold filter-trap control and protection system, autonomous and air heat exchangers, steam generator. The approach to the development of the equipment is based on maximum use of the experience gained in operating BN-350 and -600 as well as experience in developing the BN-800 design, which gives a basis for ensuring reliable operation of the BN-1200 equipment. New solutions for improving the technical-economic indicators and increasing the safety of a power-generating unit, whose validation required R&D work, are examined at the same time.

Experience in operating the BN-600 sodium-cooled fast reactor during its nominal service life as well as its service life extension period, an additional 15 years, is described. Information is presented on the performance indicators which were achieved and deviations from the normal operating regime which occurred when the reactor was first started up. The degree to which they affect the safety and technical-economic performance of the facility is evaluated. It is concluded on the basis of an analysis of the BN-600 operating experience that sodium-cooled fast reactors have now been mastered commercially and that their prospects for further development are good.

The main stages of the development of sodium-cooled fast reactors in Russia are described. The statistical information on the deviations from the normal regime of functioning that occur in BOR-60 and BN-600 operation is presented. The important role of BN-600 at the Beloyarskaya nuclear power plant in the validation of sodium-cooled fast reactors is shown. A conclusion is drawn on the basis of a review of the operating experience about the level of mastery of sodium-cooled fast reactors in Russia and the prospects for further development of such reactors are analyzed taking account of this experience.

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.

Experimental results in favour of the existence of a new type of cluster decay called "collinear cluster tri-partition", CCT, are presented. They are based on two different experiments with binary co- incidences and measurements of the masses and energies of the two fragments, as well as using in one of the experiments observables sensitive to the nuclear charge of the fission fragments. A relatively high yield of the CCT-effect (more than 10 −3 per binary fission) is likely due to the favourable Q-values (more positive than binary) and is expected due to a collective motion through very elongated (hyper-deformed) pre-scission shapes of the mother system. The process is considered to result from a sequential process, where a heavy cluster (lead as in the case of known cluster radioactivity) is replaced by pairs of two lighter clusters such as the magic isotopes of Sn/Ni or Sn/Ge.

The BN-1800 power-generating unit is designed to meet the requirements of the strategy for developing atomic energy in Russia in the first half of the 21st century. The development time is the next 15 years and construction could start after 2020. The design is innovative and includes the development of key new technical solutions as compared with the BN-800 reactor which is now under construction.

Results of two different experiments for the study of fission of 252Cf (sf) events in coincidence with neutrons are reported. Two time-of-flight-energy (TOF-E detectors systems have been used. The fission fragment masses were obtained in a double arm coincidence set-up, where the missing mass in the binary decay is used to characterise ternary fission as a collinear cluster tri-partition (CCT). The 3He filled neutron counters have been arranged so as to detect principally neutrons emitted from an isotropic source in the laboratory frame. The fission events connected to the larger experimental neutron multiplicities show a wide range in the missing-mass spectrum, down to $ \alpha$ -particles, carbon and oxygen isotopes. These are linked with magic nuclei in the binary mass-mass correlations of the fission fragments. These neutron gated data are virtually free from background events from scattered binary fission fragments. The ungated spectra are compared to those of the previous data from our previous article (Eur. Phys. J. A. 45, 29 (2010)), the observed structures agree well with the manifestations of the collinear cluster tri-partition of 252Cf (sf) observed earlier. Several new families of the CCT modes are observed.

In thenatSn+20Ne (164,196 MeV) reactions gamma-ray spectra were observed in coincidence with fast alpha particles forward peaked and with those evaporated into a backward hemisphere. The observed differences in the form of the gamma-ray spectra and in the corresponding yields of high-energy gamma-rays are preliminary related to the time evolution of the deformation of the nuclear systems formed in the heavy ion induced fusion reaction.

Zn diffusion into AlxGa1−xAs from polymer spin-on films has been investigated. An increase in Zn diffusivity has been observed with increase in the content of Al in A1GaAs compounds. The effect has been related to more coefficient of self-diffusion for Al than for Ga. The availability of the near-surface layer enriched with Al in epitaxial AlGaAs wafers has been found to result in poor reproducible diffusion characteristics.

The initial diffusion stage (lIDS) of Zn in InP from polymer spin-on films has been investigated. The threshold diffusion temperature of 375°C has been established. It has been found that the heavily-doped near-surface layer, that consisted of electrically neutral zinc-containing complexes, was formed at IDS, while a low part of Zn was electrically active. The Zn diffusivity during IDS has been found to be at least two orders of magnitude more than the Zn diffusivity obtained after an isothermal diffusion.

The spectra of theKX-rays of reaction products were observed in coincidence with high energy gamma-rays (Eγ≧10 MeV) in thenatSn+40Ar (EAr=300 MeV) and68Zn +64Zn (EZn=290 MeV) reactions. Two groups ofKX-rays can be clearly identified in the spectra. The first one corresponds to the evaporation residue of the compound nucleus and the second one to the target-like products of the reaction. The spectra of gamma transitions gated by theKX-rays of the evaporation residues were measured in both reactions. The relative yields and the positions of the broad shoulders observed at an energyEγ≧10 MeV in these spectra, differ drastically in the asymmetric and the symmetric systems. The ratio between the yields of gamma-rays emitted at angles of 0° and 90° to the beam direction was determined in thenatSn+40Ar reaction. It was found to be greater than unity only atEγ=(10–14) MeV. This experimental evidence may indicate the emission of high energy gamma-rays from the dinuclear system prior to the formation of the compound nucleus.