[en] Considering three-dimensional Chern-Simons theory, either coupled to matter or with a Yang-Mills term, we show the validity of a trace identity, playing the role of a local form of the Callan-Symanzik equation, in all orders of perturbation theory. From this we deduce the vanishing of the β-function associated to the Chern-Simons coupling constant and the full finiteness in the case of the Yang-Mills Chern-Simons theory. The main ingredient in the proof of the latter property is the non invariance of the Chern-Simons from under the gauge transformations. Our results hold for the three-dimensional Chern-Simons model in a general Riemannian manifold. (author)

[en] The decomposition of PCP in water induced by γ-irradiation has been studied at low PCP concentration under various conditions. PCP is consumed linearly with increasing absorbed doses. PCP could be decomposed almost completely by γ-irradiation at relatively high doses. Chloride ions are increased simultaneously with the consumption of PCP. The amount of chloride increases also linearly with the increasing absorbed dose. At relatively high absorbed dose, almost all chloride atoms in PCP are eliminated. Chemical oxygen demand (COD) has been measured after irradiation. Ozone is a powerful oxidizing agent for PCP. After saturation of 1.09x10^-4 mol.dm^-3 PCP aqueous solution with ozone, PCP concentration drops to 1.6x10^-5 mol.dm^-3. The combination of ozonation-ionizing radiation treatment is very effective, which greatly decreased the dose needed. pH and chemical oxygen demand also have been measured after ozonation and irradiation

[en] Medical advances that have prolonged the average life span have generated increased need for new materials that can be used as tissue and organ replacements, drug delivery systems and/or components of devices related to therapy and diagnosis. The first man-made plastic used as surgical implant was celluloid, applied for cranial defect repair. However, the first users applied commercial materials with no regard for their purity, biostability and post-operative interaction with the organism. Thus, these materials evoked a strong tissue reaction and were unacceptable. The first polymer which gained acceptance for man-made plastic was poly(methyl methacrylate). But the first polymer of choice, precursor of the broad class of materials known today as hydrogels, was poly(hydroxyethyl methacrylate) synthesized in the fifties by Wichterle and Lim. HEMA and its various combinations with other, both hydrophilic and hydrophobic, polymers are till now the most often used hydrogels for medical purposes. In the early fifties, the pioneers of the radiation chemistry of polymers began some experiments with radiation crosslinking, also with hydrophilic polymers. However, hydrogels were analyzed mainly from the point of view of phenomena associated with mechanism of reactions, topology of network, and relations between radiation parameters of the processes. Fundamental monographs on radiation polymer physics and chemistry written by Charlesby (1960) and Chapiro (1962) proceed from this time. The noticeable interest in application of radiation to obtain hydrogels for biomedical purposes began in the late sixties as a result of the papers and patents published by Japanese and American scientists. Among others, the team of the Takasaki Radiation Chemistry Research Establishment headed by Kaetsu as well as Hoffman and his colleagues from the Center of Bioengineering, University of Washington have created the base for spreading interest in the field of biomaterials formed by means of radiation technique. Immobilization of biologically active species in hydrogel matrices, their use as drug delivery systems and enzyme traps as well as modification of material surfaces to improve their biocompatibility and ability to bond antigens and antibodies have been the main subject of their investigations. The rising interest in the field of application of radiation to bioengineering was also recognized by the International Atoimc Energy Agency, which has initiated the international programs relating to those studies. In these lectures some directions of investigations on the formation of hydrogels and their applications for biomedical purposes have been specified. Also, some examples of commercialized products being produced by means of radiation technique have been presented

[en] A new pilot/demonstrative semi-mobile irradiation plant, named TRIRIS (TRIsaia-RIfiuti-Sterilizzazione, namely ''Trisaia Res. Center - Wastes - Sterilization''), has been designed and erected in order to propose and explore new technological opportunities, based on in ''in-situ'' effective cleaning process. The main general goal is to face increased problems and concerns related to the treatment/disposal of different solid-liquid wastes, particularly with reference to emergency situation (e.g. need of quick environment restoring operation following an accident with groundwater pollution). The project, which was jointly carried out by ENEA and Hitesys Co., an Italian electron accelerators manufacturer, foresees a LINAC type EB-machine (s band) having 4-6 MeV and till 1000 W as beam features. A highly flexible automatic system allows materials (solid or liquid wastes) transporting and handling to be equipped with a belt conveyor and a piping net. Scattered radiation shielding is performed by a water pool surrounding the EB-machine head, filled up before operations. Auxiliary systems, control console and analytical chemical laboratories are hosted in suitable containers near the plant and are easily transportable. The whole plant and annexed systems disassembling and reassembling in a new site can be easily carried out in a short time (few days). The plant, located at ENEA-Trisaia Res. Center (Basilicata, southern Italy), allows a large operative flexibility: groundwater and wastewater decontamination (1800 to 70 kg/h in the 1 to 25 kGy dose range), organic and chlorinated waste streams (25 kg/h at 75 kGy), solid hospital wastes (50 kg/h at 35 kGy) or hazardous wastes like polycyclic aromatic compounds (180 to 35 kg/h in the 10 to 50 kGy dose range). The paper describes and illustrates the plant in details and presents the first available operating results so far performed by the installed plant

[en] The proper design of the irradiation vessel of electron beam flue gases treatment plant and resultant optimum gas flow pattern is a very important factor to get a high removal efficiency of toxic materials from flue gases. Radioisotope tracer experiments were conducted to study the residence time distribution of gas flow in a cylindrical irradiation vessel. A few mCi of gaseous radioisotope tracer Ar-41 was injected to the upstream of the vessel and the input and output response were measured with two NaI scintillation detectors. The same experiment was conducted after the modification of the vessel by introducing 4 baffles. The experimental data were analyzed to calculate mean residence times and mixing characteristics of each system using the residence time distribution (RTD) analysis software. A method to estimate pollutant removal efficiencies of an irradiation vessel from the residence time distributions measured by radiotracer experiments was suggested. The analytical results were compared to evaluate the effect of the baffles on the removal efficiency of the plant

[en] Mochovce NPP is the last one of this kind and compared to its predecessors, it is characterized by several modifications which contribute to the improvement of the safety level. In addition based on Nuclear Regulatory Authority requirements and based on documents: - IAEA - Safety Issues and their ranking for NPP WWER 440/213, - IAEA - Safety Improvement of Mochovce NPP Project Review Mission, - Riskaudit - Evaluation of the Mochovce NPP Safety Improvements. Additional safety measures have been implemented before commissioning. The consortium EUCOM (FRAMATOME - SIEMENS), SKODA Praha, ENERGOPROJEKT Praha, Russian organizations and VUJE Trnava Nuclear Power Plants research institute were selected for design and implementation of the safety measures. The papers summarized, safety requirements, safety measures implemented, results of commissioning and results of safety analysis report evaluation. (author)

[en] In the frame of Temelin NPP PSA Project the PSA models have been developed covering Level 1 both at power and shutdown states of operation, external events and the Level 2 analyses. The hierarchical structure established for the performance of the Temelin PSA was determined from the outset by the requirement for the production of a living PSA capable of being used for both an in depth analysis of plant design and operation as well as on-line use in real time. The development, key functional requirements, status and use of Safety Monitor 2.0 for Temelin NPP is described as well as one of the Safety Monitor applications - evaluation of deterministic allowed outage times. (author)

[en] This paper presents an overview of the aging of metal components in U.S. Light Water Reactors. The types of degradation being experienced in components such as the pressure vessel, piping, reactor internals, and steam generators, and the programs being implemented to manage the degradation are discussed. (author)

[en] A theoretical and experimental study of the dynamic behavior of a boiling channel is presented. In particular, the existence of different basins of attraction during instabilities was established. A fully analytical treatment of boiling channel dynamics were performed using a algebraic delay model. Subcritical and supercritical Hopf bifurcations could be identified and analyzed using perturbation methods. The derivation of a fully analytical criterion for Hopf bifurcation transcription was applied to determine the amplitude of the limit cycles and the maximum allowed perturbations necessary to break the system stability. A lumped parameters model which allows the representation of flow reversal is presented. The dynamic of very large amplitude oscillations, out of the Hopf bifurcation domain, was studied. The analysis revealed the existence of new dynamical basins of attraction, where the system may evolve to and return from with hysteresis. Finally, an experimental study was conducted, in a water loop at atmospheric pressure, designed to reproduce the operating conditions analyzed in the theory. Different dynamic phase previously predicted in the theory were found and their nonlinear characteristics were studied. In particular, subcritical and supercritical Hopf bifurcations and very large amplitude oscillations with flow reversal were identified. (author). 53 refs., figs

No abstract available