[en] A three dimensional analysis of NEA-NSC 3-D PWR core transient benchmark of uncontrolled control rods withdrawal at zero power is presented. The analysis is performed using the three dimensional code QUABOX/CUBBOX-HYCA which combines coarse mesh neutron flux expansion method with a parallel channel model for the thermal hydraulics. The results for steady state and transient calculations are prepared in a format suitable for inter-comparison with results of other group. (author)

[en] A drive through detector systems using four plastic scintillators and associated electronics for the detections of small amounts or uranium or plutonium in cars is described. The system has been calibrated with various sample of special nuclear material and the lower detection limits are presented. (author)

[en] Experimental investigation of the Langmuir probe characteristic is a magnetized plasma with an electron current along the magnetic field direction shows that the standard procedure for determination of the electron temperature and plasma density, which is applicable in a current - free magnetized plasma, gives erroneous results for these plasma parameters. However, more precise values of the plasma parameters can be calculated from the ion saturation currents and electron temperatures obtained with that procedure for two opposite orientations of the one - sided planar probe collecting surface with respect to the direction of the electron drift. With the existing theoretical models only the order of magnitude of the electron drift velocity can be accurately determined from the measured electron saturation currents for the two probe orientations. (author)

[en] One of aspects of progression from off-line time independent Probabilistic Safety Assessment (PSA) towards on-line time dependent PSA or dynamic PSA, which is needed step leading to the Living PSA, is shown in the paper. It is the comparison of both testing strategies applied to the redundant components or systems. They are sequential and staggered testing strategies using subsystem mean unavailabilities which are the roots for the mean values, are shown and compared for the both cases. (author)

[en] Human error has been recognized as the main contributor to the occurrence of incidents in large technological systems such as nuclear power plants. Recent researches have concluded that human errors are unavoidable side effects of exploration of acceptable performance during adaptation to the unknown changes in the environment. To assist the operators in coping with unforeseen situations, the innovative error tolerant interface systems have been proposed to provide the operators with opportunities to make hypothetical tests without having to carry them out directly on the plant in potentially irreversible conditions. On the other hand, the degree of success of introduction of any new system into a tightly-coupled complex socio-technological system is known to be a great deal dependent upon the degree of harmony of that system with the organization s framework and attitudes. Error tolerant interface systems with features of simplicity, transparency, error detectability and recoverability provide a forgiving cognition environment where the effects of errors are observable and recoverable. The nature of these systems are likely to be more consistent with flexible and rather plain organizational structures, in which static and punitive concepts of human error are modified on the favour of dynamic and adaptive approaches. In this paper the features of error tolerant interface systems are explained and their consistent organizational structures are explored. (author)

[en] Four VVER-440 units are now under exploitation at Bohunice-site in Slovakia. Fuel cycle development of Unit No.3 and No.4 (type 213) is discussed and compared with equilibrium cycles in this paper. (author)

[en] Reactor physics safety analysis supporting the power upgrading from 1MW to 2MW of a typical TRIGA Mark II reactor is presented for steady state and pulse operation. The analysis is performed for mixed core configuration consisting of two types of fuel elements: standard 8,5% or 12% stainless-steel clad fuel elements and LEU fuel elements (20% uranium concentration). The following reactor physics codes are applied: WIMS, TRIGAC, EXTERMINATOR, PULSTRI and TRISTAN. Results of the calculations are compared to experiments for steady state operation at 1 MW. The analysis shows that besides technical modifications of the core (installation of an additional control rod) also some strict administrative limitations have to be imposed on operational parameters (excess reactivity, pulse reactivity, core composition) to assure safe operation within design limits. (author)

[en] Neutron activation analysis requires a knowledge of the values for the Westcott g factors, the resonance integral I 0 and 2200 ms^-1 cross section σ₀ for the (n, γ) reaction, Q₀ defined as the ratio I₀ /σ₀ and the effective resonance energy E-bar_r. The required constants can be calculated from the JEF 2.2 evaluated nuclear data files. A sensitivity study was carried out to investigate the influence of the spectral parameter α on E-bar_r. The sensitivity of I₀ to temperature due to Doppler broadening was also investigated. The results obtained were compared to those reported in the literature. Further, the calculated parameters were then applied to the analysis of a number of standard samples. (author)

[en] Continuous efforts to ensure the safety of nuclear installations in Slovenia have led to comprehensive analysis of Levels II and III of hypothetic station blackout accident modelled using the tools at our disposal. This paper represents the thermal hydraulic and radionuclide transport part of the overall effort. MARCH3 and VANESA modules of Source Term Code Package were used to analyze four different scenario depending on different reactor coolant pump leak rate (125 gpm and 400 gpm, respectively) and containment design pressure (i.e. 0.309 Mpa and 0.785 Mpa). The final aim of the project was to prepare input into the Level III analyses of the accident. The accident starts by loss of off-site power combined with loss of diesel generators. The turbine driven auxiliary feedwater pump operates additional two hours after the inception of the accident. The results are given in form of graphs displaying reactor coolant system and containment parameters. (author)

[en] Outside diameter stress corrosion cracking at the tube to tube support plate intersections is assessed in the paper. The impact of defect specific maintenance on steam generator operation safety and reliability was investigated. This was performed by comparing efficiencies of defect specific and traditional maintenance strategy. The efficiency was studied through expected primary-to-secondary leak rate and tube rupture probability in a case of postulated accidental operating conditions, and number of tubes which shall be plugged using both maintenance strategies. In general, the efficiency of specific maintenance is function of particular steam generator and operating cycle. (author)