[en] Construction of a deep geological repository is a very demanding and costly task. By now, countries that have Candu reactors, have not processed the spent fuel passing to the interim storage as a preliminary step of final disposal within the nuclear fuel cycle back-end. Romania, in comparison to other nations, represents a rather small territory, with high population density, wherein the geological formation areas with radioactive waste storage potential are limited and restricted not only from the point of view of the selection criteria due to the rocks natural characteristics, but also from the point of view of their involvement in social and economical activities. In the framework of the national R and D Programs, series of 'Map investigations' have been made regarding the selection and preliminary characterization of the host geological formation for the nation's spent fuel deep geological repository. The fact that Romania has many deposits of natural gas, oil, ore and geothermal water, and intensively utilizes soil and also is very forested, cause some of the apparent acceptable sites to be rejected in the subsequent analysis. Currently, according to the Law on the spent fuel and radioactive waste management, including disposal, The National Agency of Radioactive Waste is responsible and coordinates the national strategy in the field and, subsequently, further actions will be decided. The Romanian National Strategy, approved in 2004, projects the operation of a deep geological repository to begin in 2055. (authors)

[en] Silicon oxide (a-SiO) is one of the most used silicon-based materials in optoelectronic and microelectronic technology. It is well-known that the electronic properties are linked to the material structure, which depends on the deposition technique and on the details of the deposition. Silicon suboxide (a-SiO _x 0 < x < 2) layers were prepared by r.f. magnetron-sputtering from a polycrystalline silicon target in a well defined oxidation environment. Optical Emission Spectroscopy (OES) was employed to study the plasma used in SiO _x depositions. Theoretical calculations performed in the frame of electron impact excitation mechanism for argon and atomic oxygen corroborated with electron impact dissociation of the molecular oxygen have shown the strong influence of the electron temperature on the rate coefficients of photons' production. Correlation functions between the OES signals assigned to silicon and oxygen atoms from plasma (gas phase) and the SiO _x layer composition (infrared and energy dispersive X-ray investigated) have been found. Based on these functions, the OES plasma monitoring is proposed as a tool to control in-situ and in direct time the SiO _x layer composition

[en] The paper aims to be an integrated approach for the containment and isolation of spent fuel and / or long lived radioactive wastes in a Deep Geologic Repository in Romania. Several scenarios could be defined for the management of spent fuel and long lived radioactive waste in Romania considering many specific constraints in Romania (political, geological, economic, demographic, etc.). This paper intends to be an upgrade of several Research, Development and Demonstration (RD&D) works performed by SITON specialists on this subject, taking into account also the conclusions of the Workshop ôCost estimation on spent nuclear fuel disposal in Romaniaö organized by IAEA in cooperation with ANDR at the beginning of this year in Romania.This paper is, also, addressed to decision makers with target on to adopt the best strategy for construction of Deep Geologic Repository in Romania. (authors)

[en] The generation of broadband microwave frequency comb from a femtosecond pulse train by direct photodetection opens the possibility for high-accuracy length measurements of long distances. We demonstrate a relatively simple realization of this measurement principle: an electronic distance measurement system based on a time-of-flight approach, driven by a femtosecond fibre laser source as a modulator. By the evaluation of the phase shifts of two distinct comb frequencies, a coarse and a fine measurement of the absolute distance can be performed. The range of the measurement system is demonstrated up to a length of 100 m. The experimental comparison of the femtosecond laser system with a conventional reference counting interferometer shows a precision better than ±10 µm at 100 m, corresponding to a relative measurement uncertainty of 1 × 10⁻⁷ L. The limiting factors for the measurement uncertainty of the system are theoretically investigated and shown to be of the same order of magnitude

[en] Thin films of a-SiO _x (0 < x < 2) were prepared by reactive r.f. magnetron sputtering from a polycrystalline-silicon target in an Ar/O₂ gas mixture. The oxygen partial pressure in the deposition chamber was varied so as to obtain films with different values of x. The plasma was monitored, during depositions, by optical emission spectroscopy (OES) system. Energy dispersive X-ray (EDX) measurements and infra-red (IR) spectroscopy were used to study the compositional and structural properties of the deposited layers. Structural modifications of SiO _x thin films have been induced by UV photons' bombardment (wavelength of 248 nm) using a pulsed laser. IR spectroscopy and X-ray photoemission spectroscopy (XPS) were used to investigate the structural changes as a function of x value and incident energy. SiO _x phase separation by spinodal decomposition was revealed. The IR peak position shifted towards high wavenumber values when the laser energy is increased. Values corresponding to the SiO₂ material (only Si⁴⁺) have been found for laser irradiated samples, independently on the original x value. The phase separation process has a threshold energy that is in agreement with theoretical values calculated for the dissociation energy of the investigated material. For high values of the laser energy, crystalline silicon embedded in oxygen-rich silicon oxide was revealed by Raman spectroscopy

[en] Humidity is one of the key atmospheric parameters influencing the refractive index of air. Consequently, humidity influences all length measurements whose scale is derived from the speed of light. In this work, we present two laser spectrometers developed for determining the average humidity of air over a long measurement path where local variations may be difficult to measure using conventional sensors. Further, these laser-based systems allow, in principle, good spatial overlap with the beams used in dimensional measurements. The developed systems were compared to each other and to traceable reference sensors during a 65 h measurement campaign. The performance of the systems was investigated under three different conditions: steady state, humidity transient and temperature transient. Both systems were separately tested in outdoor environment at distances up to several hundreds of metres. The measurement results demonstrate that the systems are able to measure the relative humidity below the 4% uncertainty level both in indoor and in outdoor environment. (paper)

[en] Brosamler’s formula gives a probabilistic representation of the solution of the Neumann problem for the Laplacian on a smooth bounded domain $D\subset <!--\; ???\; -->{\mathbb{R}}^n$ in terms of the reflecting Brownian motion in D. The original proof, as well as other proofs in the literature (e.g., in the case of Lipschitz domains), are based on potential theory (transition densities of the reflecting Brownian motion). We give new proofs of Brosamler’s formula using (path trajectories of) stochastic processes. More precisely, we use a connection between the Dirichlet and the Neumann boundary problems, and the explicit description of the reflecting Brownian motion and its boundary local time in terms of the free Brownian motion. The results are obtained in the case of the Euclidean unit ball in any dimension and in the case of smooth $C^{1,\mathrm{\alpha <!--\; ??\; -->}}$ planar simply connected domains, for continuous boundary data, and then extended to the case of bounded measurable data, respectively integrable boundary data. A new Brosamler-type formula in terms of the free Brownian motion is also given.

[en] The Saligny site geological barrier - thick unsaturated zone including red clay with, mainly, a smectitic mineralogical component, has a good safety performance proved by different specific software in different stages of siting process. The geological setting for a wastes disposal site is the starting point for both defining current in situ conditions and predicting the future conditions. The siting process for LILW ground disposal included data from specific field and laboratory works for each stage used in different safety performance evaluation. In 1996, the Cernavoda site was considered a very good solution from the geological conditions point of view at the beginning of the characterization stage. However, according to the IAEA standards (Safety Guide No.111-G-3,1994), the purpose of the siting process is not to get to the best solution but to find out 'an acceptable solution, with sufficient safety reserves'. The 1996 preliminary performance assessment (using SUTRA, SWMS - 2D, and CHAIN - 2D, based on the investigation program results) proved that the Saligny site has sufficient safety reserves. Detailed field and investigation works were performed in Saligny preferred site including an experimental area to test the improvement method by compaction in a 3 m thickness backfill. Also, in 2007 there are a preliminary evaluation site, using specific codes, as follows: HYDRUS 2D for water flow simulation and FEHM for transport simulation of H-3, Cs-137, C-14, Co-60, Sr-90 in unsaturated zone, FEHM for water circulation and C-14 transport in saturated zone, and AMBER for contaminant transports both in saturated and unsaturated zone. (authors)

[en] The calibration and verification of high-precision electronic distance meters (EDMs) requires well-characterized and calibrated geodetic baselines. As the length measurements are performed typically over several hundred metres in air, a thorough understanding of the environmental conditions is necessary. In the course of a major refurbishment, the 600 m baseline of the Physikalisch-Technische Bundesanstalt at Braunschweig, Germany, was equipped with a dense environmental sensor network. This paper presents the characterization of this novel reference baseline, including the calibration of the inter-pillar distances, and identifies the major sources of uncertainty for such a length standard. A preliminary expanded standard uncertainty (k = 2) of U(l)_k=2 = √(6.2x10^-4 m)² + (7.6x10^-7 l)² is deduced for single-slope distance comparisons on the baseline. In the course of a full calibration, the additive constant c_EDM of an EDM can currently be determined with an expanded uncertainty of U(c_EDM)_k=2 = 6.1 × 10⁻⁵ m, and its scale correction s_EDM with an expanded uncertainty of U(s_EDM)_k=2 = 8.2 × 10⁻⁷. As an example, a femtosecond laser-based distance measurement over 600 m on this baseline is presented. (paper)

[en] INPRO objectives and status of the IAEA project started in 2001 and concerns the deployment of Innovative Nuclear Systems (INS) in 21st century, as solution to sustainable power development. The last achievements and the new INPRO Steering Committee directions established for 2010-2011 period, are presented. A balanced analysis of needs, resources and expectations, justifies the Romanian Statement at the 14th Steering Committee Meeting (SCM), and participant as an observer in three Collaborative Projects, in Common User Considerations (CUC) by Developing Countries for Future NPP and in SCM. The feedback of the last participatory actions in the project, justifies the Nuclear Agency recommendations for Nuclear National Program (PNN) adjustments: first, the need to apply INPRO methodology in a new national study regarding INS perspective and opportunity in Romania to use CANDU NPPs for LWRs fuel closing cycle at international level; secondly, the need to improve commitment of policy makers in forecasting financial INS support; and thirdly, to sustain the European legislation and international and national arrangements in order to facilitate nuclear regional services. (authors)