Development and Testing of Fuel Elements with Vibrationally Compacted Oxide Fuel for Fast Reactors

The main results of a series of scientific-research and technological studies performed at the State Science Center of the Russian Federation – Scientific-Research Institute of Nuclear Reactors to substantiate the use of fuel elements with vibrationally compacted oxide fuel in fast reactors are presented. In the course of this work, the physical-mechanical and technological characteristics of granular UO₂ and UPuO₂ fuel were studied; radiation tests and materials-engineering investigations of experimental and test fuel elements were performed in BOR-60, BN-350, and -600 reactors. More than 30,000 fuel elements were fabricated. Maximum burnup 30% heavy atoms was attained in BOR-60 using fuel assemblies with the standard construction and 32.3% heavy atoms was obtained using experimental fuel elements with a collapsible fuel assembly. In testing fuel elements with vibrationally compacted UPuO₂ in BN-600, maximum burnup of 9.6% (10.8% heavy atoms for individual fuel elements) was achieved. Postreactor investigations showed that the service life of the fuel elements is determined only by the choice of the cladding material. In accordance with the concept developed at the Ministry of Atomic Energy of Russia for the utilization of weapons plutonium, the Institute set about to implement in practice a technology for converting the metallic weapons-grade plutonium into mixed uranium–plutonium oxide fuel on the basis of pyroelectrochemistry and vibrational compaction.     

Room-temperature optical absorption in the InAs/GaAs quantum-dot superlattice under an electric field

Electroluminescence and absorption spectra of a ten-layer InAs/GaAs quantum dot (QD) superlattice built in a two-section laser with sections of equal length is experimentally studied at room temperature. The thickness of the GaAs spacer layer between InAs QD layers, determined by transmission electron microscopy, is ∼6 nm. In contrast to tunnel-coupled QDs, QD superlattices amplify the optical polarization intensity and waveguide absorption of the TM mode in comparison with the TE mode. It is found that variations in the multimodal periodic spectrum of differential absorption of the QD superlattice structure are strongly linearly dependent on the applied electric field. Differential absorption spectra exhibit the Wannier-Stark effect in the InAs/GaAs QD superlattice, in which, in the presence of an external electric field, coupling of wave functions of miniband electron states is suppressed and a series of discrete levels called the Wannier-Stark ladder states are formed.     

Plasma Heating of Periclase-Carbonaceous Refractory for Lining of Steel Ladles

Metallurgist - The paper presents the experimental results on plasma heating of fired periclase-carbonaceous refractory material. A high heating rate of more than 1000°C/h was achieved. The...     

Near-threshold mode synchronization and Q switching in diode lasers with a fast saturated absorber

The near-threshold lasing regimes of AlGaAs lasers with an implanted saturated absorber under short pulsed pumping are investigated experimentally. A near-threshold modesynchronization regime is obtained.     

Production of “soft” paraffins in dewaxing with urea solution

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 4, pp 12–13, April, 1992.     

Calculation of energy losses in plunger pairs of pumps in oilfield installations

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 8, pp. 12–13, August, 1991.     

On the gain properties of “thin” elastically strained InGaAs/InGaAlAs quantum wells emitting in the near-infrared spectral region near 1550 nm

The results of experimental studies of the gain properties of “thin” (3.2 nm thick) elastically strained InGaAs/InGaAlAs quantum wells emitting in the near-infrared spectral region near 1550 nm are presented. The results of studying the threshold and gain characteristics of stripe laser diodes with active regions based on “thin” quantum wells with a lattice–substrate mismatch of +1.0% show that the quantum wells under study exhibit a high modal gain of 11 cm^–1 and a low transparency current density of 46 A/cm² per quantum well.     

Nonstationary characteristics of a single-server queue system with nonordinary input flow

A single-server queue system with nonordinary input flow that depends on the queue length is considered. Sufficient existence conditions for the stationary distribution of the queue length provided that the process under study is an eigen process are obtained. Recurrence formulas for the Laplace transform of the nonstationary distributions of the queue length are derived.