Boris E. Burakov

The fabrication of a photovoltaic nuclear electric battery consisting of a radioactive diamond core and an InGaP photoconverter is described. An electrical circuit for a nuclear battery has been proposed. A battery core has been manufactured using a polished self-glowing diamond plate made of artificial single-crystal IIb-diamond activated with 0.008 wt. % 14C. The optimal geometric parameters of the proposed diamond plates have been determined, and a prospective photovoltaic converter was developed. The optimal design of the nuclear diamond battery, including possible increase in power yield, is discussed.

There is a novel study of typomorphic features of picroilmenites, pyropes, and spinelides from the alluvium of the Legkiy Creek’s upper reaches, the right tributary of the Nalim-Rassokha River. Presence of a new kimberlite field in the Anabar Massif, in the basin of the Nalim-Rassokha and Ulakhan-Staraya rivers, confirms Krasnoyarsk geologists’ arguments (1984). Characteristic surfaces of mineral associations prove to pertain to the primary halo of kimberlite indicator minerals. Picroilmenites comparable to inclusions in diamonds and diamond-bearing peridotites are absent in the alluvium of the Bolshaya Kuonamka and Bargydamalaakh rivers draining non-diamond-bearing kimberlite fields. The quantitative ratio of pyropes of lherzolite (86 %) and dunite-harzburgite (11 %) parageneses is typical of kimberlites. The spinelides association originates from deep ultramafic rocks and the groundmass of kimberlites. There are grounds for discovering a new Rassokha diamond-bearing kimberlite field in the Anabar Massif, in the basin of the Nalim-Rassokha and Ulakhan-Staraya rivers.

Two crystalline phases, which are analogues of common secondary uranyl minerals, namely, becquerelite (Ca[(UO₂)₆O₄ (OH)₆]·8H₂O) and phurcalite (Ca₂[(UO₂)₃O₂ (PO₄)₂]·7H₂O) were identified on the surface of a Chernobyl corium-containing sample affected by hydrothermal alteration in distilled water at 150 °C for one year. Phases were characterized using Single-Crystal X-ray Diffraction Analysis (SCXRD) as well as optical and scanning electron microscopy. Features of the structural architecture of novel phases, which come from the specific chemical composition of the initial fragment of Chernobyl sample, are reported and discussed. Precise identification of these phases is important for modelling of severe nuclear accidents and their long-term consequences, including expected corium–water interaction processes at three damaged Units of the Nuclear Power Plant Fukushima Daiichi.

In this work samples of ZrO2-Y2O3-Eu2O3 and HfO2-Y2O3-Eu2O3. ceramics are synthesized. Cathodoluminescent studies were carried out. It is shown that, under the chosen synthesis regimes, the ZrO2-Y2O3-Eu2O3 ceramic is stabilized in the cubic phase and is single-phase. The HfO2-Y2O3-Eu2O3ceramic is also stabilized in the cubic phase with small amount of inclusions of the tetragonal phase. Also, in the HfO2-Y2O3-Eu2O3 sample, an inhomogeneous distribution of point defects associated with oxygen deficiency is observed.

Chemical degradation of borosilicate glass doped with ²³⁸Pu was modelled in conditions of a failed underground radwaste repository in granite host rock with bentonite buffer material after penetration of aqueous solutions at temperature of 90 °C. The total duration of the experiment exceeded two years. It is shown that wet bentonite preserved its barrier function and prevents migration of plutonium to the solution. The total amount of plutonium adsorbed on bentonite clay during the experiment did not exceed 0.02% of the initial amount of plutonium in the glass sample. Estimated accumulated dose of self-irradiation of the glass sample after the experiment varies from 3.16 × 10¹⁵ to 3.39 × 10¹⁵ α-decays per gram, which is equivalent to more than 1000 years storage of ²³⁹Pu doped sample with the same Pu content. Beishan granite remained intact, with no evidence of Pu penetration into the granite matrix along mineral grain boundaries.

Complex oxides of Y3Al5O12, Gd(Nb,Ta)O4, (Zr,Hf,Y)O2, (Zr,Y)O2, activated with trivalent rare earth ions Nd3+, Eu3+ and Tb3+ have been studied in terms of their luminescent properties. These materials are promising scintillators with high radiation, chemical, and mechanical stability. The aim of the work was to develop ceramic radiation-resistant scintillators based on oxides activated by rare-earth ions. The study included: an evaluation of changes in the intensity and kinetics of luminescence decay from single crystal samples to ceramics; a study of the complete or partial replacement of light elements by heavier ones effect on the luminescent properties; a study of the possibility of using a sensitizer to increase the luminescence yield when luminescence is excited by an electron beam of medium energies.

The paper consists of two main parts: a microscopic and spectroscopic investigation of the single crystal of 17-year-old ²³⁸Pu-doped Eu-monazite, and a theoretical calculation of the properties of several structural types of orthophosphates. It is shown that actinide-doped monazite is prone to the formation of mechanically weak, poorly crystalline crust, presumably consisting of rhabdophane. Its formation is likely promoted by the formation of peroxides and, potentially, acidic compounds, due to the radiolysis of atmospheric moisture. The calculations of mixing the enthalpies and Gibbs energies of binary solid solutions of Pu and rare earth element (REE) phosphates that were performed for the principal structural types—monazite, xenotime, rhabdophane—show that, in the case of light REEs, the plutonium admixture is preferentially redistributed into the rhabdophane. This process strongly affects the behavior of actinides, leached from a monazite-based waste form. The applications of these results for the development of actinide waste forms are discussed. The current data on the behavior of real actinide-doped monazite suggest that this type of ceramic waste form is not very resistant, even in relatively short time periods.