Integrated material flow and radioactivity distribution methodology within the calculation tool for evaluation of parameters for decommissioning of nuclear installations

Decommissioning of nuclear facilities becomes an important issue in all areas of nuclear technology, mainly in their energetic applications. Decommissioning process has to be planned in the safe, ecological and economic manner. It determines the requirements on appropriate evaluation of needed technologies, media, amount of solid materials released into the environment, radioactivity of effluents, amount of radioactive waste for disposal, number and exposure of personnel and finally the financial demands. A detailed evaluation of these parameters may be done by analytical calculation approach. This approach models a real process of decommissioning with its individual basic activities. The methodology of integrated material flow and radioactivity distribution within this calculation evaluation tool is applied and implemented to describe the real decommissioning activities and their mutual relations to obtain more accurate outputs.     

A Trajectory-Based Approach for the Stability Robustness of Nonlinear Systems with Inputs

 We show, for two different definitions of semiglobal practical external stability, that the stability property holds on semi-infinite time intervals if and only if it holds on arbitrarily long but finite time intervals. These results have immediate applications in the analysis of the stability properties of highly oscillatory systems with inputs using averaging or for systems with inputs that are slowly varying. Results are stated for general flows and the stability is given with respect to arbitrary (not necessarily compact) sets. Date received: May 11, 2001. Date revised: March 14, 2002.     

Milk-alkali syndrome complicated by acute renal insufficiency]

A case of the "Burnett" syndrome complicated by acute renal insufficiency is reported. Hemodialysis and normalization of the diet helped in the end to eliminate both the milk-alkali syndrome and renal insufficiency.     

Non-local stabilization of a spherical inverted pendulum

We design a non-linear stabilizing control law for a four degree of freedom spherical inverted pendulum. The pendulum is a slim cylindrical beam attached to a horizontal plane via a universal joint; the joint is free to move in the plane under the influence of a planar force. The upright position is an unstable equilibrium of the uncontrolled system because of gravity. The objective is to design a controller so that it stabilizes the upright position starting from any position in the upper hemisphere with arbitrary velocity. We achieve this by first transforming the original system to an appropriate upper triangular form and then designing a controller which incorporates a high gain design with the method of non-linear forwarding. The control law is evaluated through computer simulations.     

Optical characterization of ultrananocrystalline diamond films

Optical properties of the ultrananocrystalline diamond films were studied by multi-sample method based on the combination of variable angle spectroscopic ellipsometry and spectroscopic reflectometry applied in the range 0.6–6.5 eV. The films were deposited by PECVD in a conventional bell jar (ASTeX type) reactor using dual frequency discharge, microwave cavity plasma and radio frequency plasma inducing dc self-bias at a substrate holder. The optical model of the samples included a surface roughness described by the Rayleigh–Rice theory and a refractive index profile in which Drude approximation was used. The results conformed with the present understanding of the polycrystalline diamond growth on the silicon substrate because the existence of silicon carbide and amorphous hydrogenated carbon film between the silicon substrate and nucleation layer was proved.     

Natural radioactivity in various surface waters in stanbul, Turkey

Gross-α and gross-β, activities of eight well and five tap water samples taken in stanbul were determined. Ra²²⁶, Rn²²², Pb²¹⁴, Bi²¹⁴, K⁴⁰, Cs¹³⁷ activity concentrations in four lake, four sea water, one snow and one rain water samples were also analyzed in order to determine their radioactivity. The results obtained showed that, in general, natural activities in drinking water samples did not exceed WHO and ITS guidelines. In sea and lake water, four samples were over WHO and TSI guidelines. Concentrations ranging from 0.007 to 0.04 Bq l⁻¹ and from 0.02 to 0.1 Bq l⁻¹ were observed for drinking water and the gross-α and gross-β activities, respectively. For all samples the gross-β activities were higher than the corresponding gross-α activities. In order to evaluate the annual effective dose equilavent of ingestion of these waters, a conservative dosimetric calculation was carried out using dose conversion factor suggested by the ICRP. An average annual effective dose equivalent of 0.84 μSv y⁻¹ for Ra²²⁶ was calculated.     

Optical characterization of diamond-like carbon thin films non-uniform in thickness using spectroscopic reflectometry

Two formulae expressing the reflectance of non-uniform thin films are presented. The first of them corresponds to the arbitrary shapes of this non-uniformity and illuminated light spot under the assumption that this non-uniformity is sufficiently slight. The second formula corresponds to the wedge-shaped non-uniformity of arbitrary magnitude within the circular light spot. It is shown that both the formulae are suitable for the successful optical characterization of non-uniform diamond-like carbon (DLC) thin films in contrast to the usually used reflectance formula for the uniform thin films. Within the optical characterization the values of the standard deviation of non-uniformity is determined together with the correct values of the mean thickness and material parameters corresponding to the dispersion model based on the parametrization of the density of electronic states. On the basis of the material parameters determined the correct spectral dependences of the optical constants of the DLC films studied are calculated.     

The morbidity indices of subjects with incorporated radioactive iodine

With the purpose of detecting long-term somatic effects of incorporated iodine, an analysis was performed of health disorders in those subjects (n = 1040) who received 131 I in therapeutic dosages 25 to 30 years ago. Discordances in pituitary-thyroid- and pituitary-adrenal axes were found to result in excessive metabolic-degenerative and vegetovascular type morbidity rates compared with the general population. Mortality index exceeds that of in the population 2.1-fold. No one of the deceased had reached the average length of human life. Halt the cases died of ischemic heart disease, 6 patients developed carcinoma of endocrine organs; these were all females, who had taken radioactive iodine prior to the age of 30 years. Thus, in remote time periods after incorporation, there develop a number of those disorders leading ultimately to reduction of the length of human life, which is believed to be one of the universal effects of irradiation.     

A longitudinal elasticity study of hair from the human head in forensic medicine

A rapid and sensitive method for assessing hair keratin stretch elasticity modulus has been developed. The technique is based on measuring the oscillation resonance frequency of hair fragments fixed at one end. The first results indicate a high sensitivity of the method and the possibility of its use in forensic medicine.