Re-evaluation of the phase relationship between plutonium and zirconium dioxides

The phase relationship between ZrO₂ and PuO₂ was examined in a low PuO₂ content region, from 3.1 to 11.2 mol% PuO₂, at temperatures between 1273 K and 1473 K, by high temperature X-ray diffractometry. The measurements were carried out in air. At 1273 K, the samples in this composition range consisted of two phases, monoclinic and cubic. Another phase, tetragonal, was observed at 1373 K. The low temperature monoclinic phase disappeared at 1473 K. It was confirmed that the monoclinic phase disappears around 1463 K; the disappearance temperature does not depend on the composition of the sample. It was, thus, inferred that there should be a eutectoid line in the phase diagram. Though the eutectoid point is not clear, the PuO₂ content at the point should be less than 3.1 mol%.     

Visible light emission from silicon: a quantum effect in highlyporous materials

The authors discuss progress in the control of the luminescent properties of porous silicon and in the understanding of the basic mechanisms which govern the light emission. The main features of porous silicon formation and properties are briefly recalled. The photoluminescence characteristics are reported. It is shown that anodic oxidation of porous silicon is a technique which provides photoluminescent layers with good mechanical properties and enhanced emission efficiency. A model accounting for the quite long measured carrier lifetimes is outlined. The electroluminescence which appears during the anodic oxidation of porous silicon in pure water was studied     

The first materials science investigations of plutonium in the laboratories of NII-9

The formation of the institute NII-9 (now the State Science Center of the Russian Federation—A. A. Bochvar All-Russia Scientific-Research Institute of Standardization in Machine Engineering), by a decree of the State Committee on Defense, in 1945 in Moscow and the production at this Institute in 1948 of substantial (milligram) quantities of metallic plutonium from uranium blocks irradiated in the F-1 reactor are recounted. Data on the organization of the work and the creation of special equipment and methods for performing investigations on microsamples of a radioactive, toxic, chemically active material are presented. These investigations led to the discovery of six allotropic modifications of plutonium the temperature ranges of their stability, the melting temperature, the characteristic features of the volume and temperature expansion at phase transitions, and the mechanical properties of the phases. The participation of the Institute staff and of A. A. Bochvar himself in the fabrication of the plutonium warhead in 1949 for the first Soviet atomic bomb is reflected. The directions of the investigations of plutonium performed in subsequent years are indicated. State Science Center of the Russian Federation—A. A. Bochvar All-Russia Scientific-Research Institute of Standardization in Machine Engineering. Translated from Atomnaya énergiya, Vol. 87, No. 3, pp. 170–174, September, 1999.     

Development of thermal fatigue damage in 1CrMoV rotor steel

Crack initiation endurances have been determined for a 1CrMoV rotor steel in uniaxial service cycle thermo-mechanical fatigue (TMF) tests formulated to simulate a range of steam turbine start cycles with a maximum temperature of 565 °C. The experimental details for these TMF tests are described.Post test inspection has been employed to characterise the associated thermal fatigue damage mechanisms for the steel which are observed to be dependent on the magnitude of the thermal transient in the TMF cycle.The lowest resistance to thermal fatigue damage development occurs in these tests when the conditions determine that the rate of creep damage accumulation below the surface exceeds the rate of fatigue crack development at the surface.