Analysis of thermal hydraulic behavior of KONVOI PWR during a design extension condition

In Nuclear Power Plants the Design Extension Conditions are more complex and severe than those postulated as Design Basis Accidents, therefore, they must be taken into account in the safety analyses. In this study, many hypothetical investigated transients are applied on KONVOI pressurized water reactor during a 6-in. (182 cm2) cold leg Small Break Loss-of-Coolant-Accident to revise the effects of all safety systems ways through their availability/ nonavailability on the thermal hydraulic behaviour of the reactor. The investigated transients are represented through three cases of Small Break Loss-of-Coolant-Accident as, case-1, without scram and all of the safety systems are failure, case-2, the normal scram actuation with failure of all safety systems (nonavailability), and finally case 3, with normal actuation scram sequence and normal sequential actuation of all safety systems (availability). These three investigated transient cases are simulated by creation a model using Analysis of Thermal-Hydraulics of LEaks and Transient code. In all transient cases, all types of reactivity feedbacks, boron, moderator density, moderator temperature and fuel temperature are considered. The steady-state results are nearly in agreement with the plant parameters available in previous literatures. The results show the importance effects of the feedbacks reactivity at Loss-of-Coolant-Accident on the fallouts power, since they are considered the key parameters for controlling the clad and fuel temperatures to maintain them below their melting point. Moreover, the calculated results in all cases show that the thermal hydraulic parameters are in acceptable ranges and encounter the safety criterion during Loss-of-Coolant-Accident the Design Extension Conditions accidents processes. Furthermore, the results show that the core uncovers and fuel heat up do not occur in KONVOI pressurized water reactor in theses the Design Extension Conditions simulations since, all safety systems provide adequate core cooling by sufficient water inventory into the core to cover it.

Assessment of the radiological situation in different areas affected by uranium mining and uranium processing in the Czech Republic

This study presents measurements of activity concentrations of natural radionuclides in selected water and soil samples taken from areas affected by the uranium industry in the surroundings of Pribram, Straz pod Ralskem and Mydlovary, Czech Republic. In these areas, the dose equivalent rate was also determined at the sampling locations and additionally also during walkabouts in the surroundings of sludge fields. The activity concentration of water samples was 0.06 ? 0.02 BqL?1 for 226Ra and 0.07 ? 0.07 mgL?1 for 238U while the mean activity concentrations of soil samples were 74 ? 70 Bqkg?1 and 80 ? 77 Bqkg?1 for 226Ra and 238U, respectively. The average value of the dose equivalent rate was of 0.15 ? 0.1 ?Svh?1. These values conform with the nature of the industrial activities which were carried out in the areas and are comparable with measurement results in similar locations worldwide.

Development of intelligent preamplifier for semiconductor detectors

The results of engineering an intelligent preamplifier for HPGe gamma-detectors are presented. An intelligent preamplifier is a low-noise, high-speed resistive feedback charge-sensitive preamplifier with a built-in microcontroller and additional units that enable control of preamplifier and detector parameters. It also allows to manage performance of the internal testing pulser, sensor of liquid nitrogen level in Dewar, humidity, pressure and temperature sensors in a sealed preamplifier section. Intelligent preamplifier operation, setup and parameter measurements are controlled by a software.

Assessment of ct simulators used in radiotherapy treatment planning in Serbia, Croatia and Bosnia and Herzegovina

The purpose of this work was to evaluate computed tomography (CT) simulators used in radiotherapy treatment planning in Serbia, Croatia and Bosnia and Herzegovina. A survey of quality assurance programmes of 24 CT simulators in 16 facilities was conducted. Dedicated CT-to-ED phantom was scanned at 120 kV and 140 kV, to obtain CT-to-ED (ED- Electron Density) conversion curves as well as CTDIvol. Thoracal phantoms were scanned in standard and extended field of view to evaluate dosimetric effect on treatment planning and delivery. Mean age of measured scanners was 5.5 years. The mean water HU value was -6.5 (all scanners, all voltages) and air HU value was -997. Extended field of view CT data differ from standard field of view and differences between conversion curves have significant dosimetric impact. The CTDI data showed large range of values between centers. Better QA of CT simulators in all countries is recommended. CT-to-ED curve could be used as default at one voltage and per manufacturer. Extended field of view imaging can be used, but treatment planning should be avoided in the regions out of standard field of view.

Radionuclides’ content in forest ecosystem located in southwestern part of Serbia

Forests, with a large coverage of lands area, represent important ecosystem. They have greater ability to absorb atmospheric pollutant, including radionuclides compared to other vegetation types. Thus it is important to monitor radionuclides concentration in forest ecosystems. The results of the first gamma-spectrometric measurements in 16500 ha large region of South-western Serbia are presented. It is investigated activity concentrations of 40K, 137Cs and 210Pb in different deciduous and evergreen trees in the region. For all investigated isotopes, it was observed tendency that the smallest activity concentrations in average were found in tree stem, than in leaves, while the highest ones were in soil. Statistical analysis did not show any differences between activity concentrations of leaves and needles, showing that both leaves and needles could be equally well used as a biomonitors.

Possibility of application nuclear magnetic resonance to measure fluid flow

The paper considers the application of nuclear magnetic resonance to measure fluid flow. The paper is of an experimental nature. Flowmeter based on nuclear magnetic resonance is extremely precise. The combined measurement uncertainty can be 0.1 %. Such a value of measurement uncertainty indicates that it is a matter of a deterministic and not of a stochastic quantity. This high degree of reliability of the method is theoretically and mathematically described. The paper presents a measurement scheme for flow measurement. Water flow measurement was performed on the principle of nuclear magnetic resonance and on the basis of tritiated water (which is considered to be the most accurate classical method). The obtained results show that the measurement of flow based on nuclear magnetic resonance is more accurate (especially at higher flow). This is explained by the higher inertial mass of HTO tritiated water molecules than the standard H2O water mass and the possible transition of tritiated water to H3HeO. In this way, it has been proven that tracing water based on nuclear magnetic resonance is the only real tracing of water by water. The obtained results shows that tracing water with tritiated or heavy water is not tracing water by water which is explained by different inertial masses.

Radiological and physico-chemical characterization of red mud as an Al-containing precursor in inorganic binders for the building industry

The potential re-use of red mud in the building and construction industry has been the subject of research of many scientists. The presented research is a contribution to the potential solution of this environmental issue through the synthesis of potential construction materials based on red mud. A promising way of recycling these secondary raw materials is the synthesis of alkali-activated binders or alkali activated materials. Alkali-activated materials or inorganic binders based on red mud are a new class of materials obtained by activation of inorganic precursors mainly constituted by silica, alumina and low content of calcium oxide. Since red mud contains radioactive elements like 226Ra and 232Th, this may be a problem for its further utilization. The content of naturally occurring radionuclides in manufactured material products with potential application in the building and construction industry is important from the standpoint of radiation protection. Gamma radiation of the primordial radionuclides, 40K and members of the uranium and thorium series, increases the external gamma dose rate. However, more and more precedence is being given to limiting the radiological dose originating from building materials on the population these days. The aim of this research was to investigate the possible influence of alkali activation-polymerization processes on the natural radioactivity of alkali activated materials synthesized by red mud (BOKSIT a. d. Milici, Zvornik, Bosnia and Herzegovina) and their structural properties. This research confirmed that during the polymerization process the natural radioactivity was reduced, and that the process of alkali activation of raw materials has an influence on natural radioactivity of synthesized materials.

Dual number automatic differentiation as applied to two-group cross-section uncertainty propagation

This work addresses the problem of propagating uncertainty from group-wise neutron cross-sections to the results of neutronics diffusion calculations. Automatic differentiation based on dual number arithmetic was applied to uncertainty propagation in the framework of local sensitivity analysis. As an illustration, we consider a two-group diffusion problem in an infinite medium, which has a solution in a closed form. We employ automatic differentiation in conjunction with the sandwich formula for uncertainty propagation in three ways. Firstly, by evaluating the analytical expression for the multiplication factor using dual number arithmetic. Then, by solving the diffusion problem with the power iteration algorithm and the algebra of dual matrices. Finally, automatic differentiation is used to calculate the partial derivatives of the production and loss operators in the perturbation formula from the adjoint-weighted technique. The numerical solution of the diffusion problem is verified against the analytical formulas and the results of the uncertainty calculations are compared with those from the global sensitivity analysis approach. The uncertainty values obtained in this work differ from values given in the literature by less than 1?10?5.

Regional scale screening over selected regions of bangladesh to identify potential sites for the disposal of low and intermediate level radioactive waste

Disposal of radioactive wastes has been emerged as a vital issue for Bangladesh as the country is actively working to be the nuclear power plant operating country by 2023-2024. Current study aims to find out potential sites for a near-surface disposal facility using geographic information system software and multi-criteria analysis method. Previously six regions (Region-1 to Region-6) were identified upon performing continental scale screening over the whole territory of Bangladesh. In the current study, regional scale screening has been performed over the Region-1 and Region-2 using five criteria divided into fifteen sub-criteria, namely earthquakes, wind speed, rainfall, cultivated-vegetated land, forests, buildings-facilities-build up areas (area), buildings-facilities-Industries-institutions (Point), population density, medium-broad road and railway, narrow road, power line, ground water table, surface water body and lastly flood were used in the analysis. The suitability map and relative importance weighting of these sub-criteria were determined by using geographic information system and multi-criteria analysis method. The overlay analysis was performed over suitability maps of each sub-criterion and found final suitability map of the Region-1 and Region-2. These suitability maps were divided into six category, namely excluded area, most suitable, suitable, moderately suitable, unsuitable and completely unsuitable. Nineteen potential sites with maximum and minimum area of 7.90 km2 and 1.15 km2 were identified from these most suitable and suitable areas. Detailed field investigation and site characterization are needed to be performed on selected potential sites to choose a final disposal site for the low and intermediate levels of radioactive waste.

Review of the thermoluminescent dosimetry method for the environmental dose monitoring

Passive solid state dosimeters, such as thermoluminescence dosimeters, provide integrated measurement of the total dose and are widely used in environmental monitoring programs. The objective of this paper is to provide a comprehensive review on the use of thermoluminescent dosimetry methods for monitoring radiation dose in the environment. The article presents the part of the research results of the project PREPAREDNESS (EMPIR 2016 call for Metrology for Environment joint research project) with a particular objective to harmonize procedures used by dosimetry services, relevant authorities and Institutes across the Europe. To achieve this, different monitoring routines that are based on passive environ mental dosimetry methods are investigated. Differences in performing specific steps such as preheating, reading, annealing, minimizing fading, and others, are analyzed. The investigation was performed by means of qualitative literature review that showed the lack of information about specific steps. The conclusion of this work is that thermoluminescent dosimetry measurement system has to be type-tested even though the testing procedure is complicated. In addition to this, control dosimeters should be introduced, International Organization for Standardization protocols should be followed during calibration, and finally, parameters influencing the measurement uncertainty have to be identified and well understood in order to pro duce ac cu rate dose measurement results.