[en] Molecular-dynamics simulations were used to calculate threshold displacement energies for each atom type in BaTiO_3 perovskite. A primary knock-on atom with an energy range between 10 and 300 eV in principal crystallographic directions at 300 K was introduced. A statistical approach has been applied calculating displacement probability curves along main crystallographic directions. For each sublattice, the simulation was repeated from different initial conditions to estimate the uncertainty in the threshold displacement energy calculated values. The threshold displacement energies vary considerably with crystallographic direction and sublattice. The weighted average threshold displacement energies are 40 eV for oxygen, 64 eV for barium and 97 eV for titanium atoms. These values are comparable to ab initio calculated and experimentally derived values in perovskites. These results are proposed as threshold displacement energies, ideal for simulation programs that use atomic displacement calculation algorithms

[en] Successfully executed radioactive waste management projects are critical to the sustainability of the nuclear industry. While there’s a tendency to think the challenges to successfully siting radioactive waste management facilities are technical, public acceptance is perhaps the biggest challenge. The social aspects of nuclear waste storage, transportation and disposal cannot be understated; hence the growing emphasis on consent-based siting. While there are examples of successful and unsuccessful siting efforts there is no single “roadmap” or “framework” to describe how to secure community consent. One such potential roadmap or framework could be Sociotechnical Systems Design, which recognizes the interaction between people and technology and considers social and technical factors that influence the functionality, practicability, acceptability, and usage of a system. A holistic analysis of any system considers five work system elements (people, technology–tools, tasks, policies–organization, and the environment) and identifies where requirements or conditions of these elements have consequences triggering changes on the others. Concurrent Engineering is a systematic approach that enables designers to consider all system elements and their interfaces throughout the life cycle by incorporating stakeholders early in the pre-design stages. The paper describes how to use a sociotechnical system that relies on a Concurrent Engineering process to achieve consent-based siting of a nuclear waste management facility. The resulting framework addresses the socioeconomic requirements of communities while facilitating communication and interaction opportunities between technical, political, and social stakeholders. This will allow communities to access information and raise concerns about nuclear waste management locally, while letting technical specialists factor these concerns into the waste management facility design, providing information where needed, and reducing the need for rework and retrofitting. Staged implementation of sociotechnical systems design supported by concurrent engineering can be key to consent-based siting and a successful nuclear waste management programme. (author)

[en] The non-radioactive biotin labelling method was employed to label bacteriophage lambda DNA. During hybridization, 1% casein was used instead of the commercial blocking reagent. DNA hybrids were detected by chemiluminescent technique. Some washing steps were detected or shortened to expedite the procedure. Steps which can be lengthened and can serve as stopping points during washing were identified. The introduced modifications did not alter the sensitivity of this nonradioactive nucleic acid detection method. Comparison of this method with the radioactive labelling and detection showed no difference in sensitivity. (Author). 4 refs.; 2 figs

[en] The spatial distribution of the gamma radiation deposited energy inside YBCO bulk samples irradiated with Co⁵⁷, Cs¹³⁷ and Co⁶⁰ sources was simulated using the Monte Carlo method. The analysis show that the energy distribution is inhomogeneous in all the cases, increasing with the source energy. The maximal deposition zone shifts deeper into the bulk material with the increment of the source energy. The different interaction mechanisms which should play relevant role in the observed effects are discussed in the text. The possible effects of the dose distribution inhomogeneity on the experimentally measured properties are also analysed. An experiment that contributes to confirm the validity of the simulation is presented. (Author)

[en] Porcelain tiles present good aesthetical properties, low water absorption and high mechanical and chemical attack resistance. The feldspar, one of its raw materials, is responsible form diminishing porosity and enhance mechanical resistance. It is normally imported, making the production more expensive. In this paper, it was studied the substitution of feldspar by nepheline under the rheological point of view, determining the optimum amount of deffloculant and the maximum concentration of solids of the suspensions. The results showed similar rheological behaviour, with a small reduction on the maximum concentration of solids as the proportion of nepheline increases. The pieces made with nepheline are darker than the ones made of feldspar; however, the magnetic separation results in lighter pieces. The formulations with nepheline as alkalis source presented a high increase of the density after heating. (author)

[en] The calculation results of the atom displacement distribution induced by gamma radiation in the superconducting material YBa₂Cu₃O_7-x are presented. Firstly, a direct calculation procedure for the atom displacement distribution inside a given material is introduced, starting from the application of the energy flux distribution values of secondary electrons, formerly calculated using the Monte Carlo method based code system MCNP-4C. Finally, calculation results of the atom displacement distribution, regarding the occupied oxygen crystalline sites, are presented for different incident gamma radiation energies, where an atom displacement threshold energy value of 20 eV was assigned to O(1-3) sites, while a value of 3.45 eV was used for the copper-oxygen chain sites at the basal plane. According to the present calculations, a predominating atom displacement rate at copper-oxygen chain sites was obtained. On the other hand, nearly linear correlations among atom displacements and energy deposition profiles were also found. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

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[en] Bi₂Sr₂CaCu2_Ox superconducting fibers synthesized by solid state reaction and textured by the method of zonal laser ablation were irradiated with 1250 and 662 keV gamma rays. The behavior of some of its superconducting properties with the exposition dose was studied by the measurement of dynamic magnetic susceptibility. It was observed that, for different dose levels according to energy of the incident radiation, the fibers preserve its superconducting intragrain properties, evidencing the high resistance of the material to the radiation damage. In all the cases were verified that with the increase of the dose the Ton of the transition grows. Two possible mechanisms that take place in this effect are analyzed in the text. The ac_X measurements allowed observing the increasing behavior of the superconducting volume fraction in the sample with the exposition dose.(Author)

[en] Methodological studies of a new Irradiation Chamber (operational parameter optimisation and characterization) as well as proton irradiation response one for a set of nowadays interesting materials at the Linear Accelerator Facilities of the High Flux Neutron Generator at the Centre of Technological Applications are presented. A new scientific problem connected with the verification of an enhancement of diffusive atomic motions in YBa₂Cu₃O_7-x ceramics under the action of proton and gamma irradiation is analysed. A new calculation algorithm of the mean temperature of the samples under the interaction with ion beams is introduced and applied to both, irradiation experimental design and planning and the evaluation of the thermal impact on the researched samples. The first findings of proton beam modification of Aluminium massive samples under severe irradiation conditions is presented and analysed. (author)