Browse

21 - 30 of 2,249 items :

Clear All
Analysis of the BEAVRS PWR benchmark using SCALE and PARCS

Abstract

This paper presents an analysis of the Benchmark for Evaluation And Validation of Reactor Simulations (BEAVRS) performed using SCALE 6.1.2 and PARCS 3.2 computer codes. The benchmark specification contains a detailed design, operational data and measurements for a real 4-loop Westinghouse pressurized water reactor (PWR). The lattice physics simulations were prepared using TRITON depletion sequence and NEWT neutron transport solver (SCALE package). The 238-neutron group library based on evaluated nuclear data file – ENDF/B-VII nuclear data libraries was applied. A set of branch and burnup calculations was prepared, and group constants in the form of PMAXS files were generated with GenPMAXS. The full-core models were prepared using the PARCS nodal-diffusion core simulator. The PMAXS libraries were used with PARCS to investigate the core operation. The hot zero power measurement data, including control rod worths and critical boron concentrations, were compared using simulations, and satisfactory results were achieved. The first fuel cycle was simulated, and acceptable agreement with boron letdown curve and measurements were obtained. Finally, conclusions and recommendations for future research were presented.

Open access
Bacillus subtilis BS-2 and Peppermint Oil as Biocontrol Agents Against Botrytis cinerea

Abstract

The purpose of this study was to assess the activity of Bacillus subtilis BS-2 and peppermint oil against Botrytis cinerea. In this study parameters such as the age and the density of the bacterial culture and the incubation temperature were taken into consideration. Furthermore, the cellulolytic activity of the bacterium was determined. The effect of peppermint oil was evaluated at a concentration range of 0.5-4.0 %. The research was conducted with a dual culture plate method. The influence of B. subtilis BS-2 and peppermint oil on the growth of B. cinerea was evaluated based on the growth rate index. It was noted that the bacterial culture occurred at an initial density of OD 560 = 1.0, cultivated at 30 °C for 48 hours demonstrated the strongest antagonistic effect (57.07 % inhibition). Furthermore, it was observed that the highest cellulolytic activity occurred on the bacteria incubated for 48 hours at 37 °C. The effect of mint oil, at the lowest concentration of 0.5-1.0 %, was much weaker on bacterial activity (1.1-12.1 % inhibition). The highest concentration (4.0 %) of mint oil caused the maximum inhibition (31.9 %) of the mycelial growth. B. subtilis BS-2 may be environmental-friendly alternatives for protecting plants against B. cinerea

Open access
Characterisation of Municipal Sewage Sludge as a Soil Improver and a Fertilizer Product

Abstract

In this study, we have determined the main important physical and chemical properties of municipal sewage sludge and compared them to the requirements of the Finnish Fertilizer Product Act and Fertilizer Product Decree in order to assess the potential utilization of this by-product as a fertilizer. Except for Hg (1.4 mg/kg d.m.), the total concentrations of Cd, Cu, Ni, Pb, Zn, Cr and As in our sewage sludge were lower that the Finnish maximum permissible heavy metal concentrations for sewage sludge used as a fertilizer products. However, the sewage sludge may be utilized as a soil improver, a growing media or as a fertilizer product in landfill sites (e.g. surface structures) or in other closed industrial areas, because the above mentioned Finnish limit values are not applied at these sites. If the sewage sludge is to be utilized in these kinds of areas, an environmental permit may be needed. According to BCR-extraction, the lowest release potential (solubility) from the sample matrix was observed for sulphur (58.4 %) and the highest for Cd (100 %).

Open access
Clinical advantages of using unflattened 6-MV and 10-MV photon beams generated by the medical accelerator Elekta Versa HD based on their dosimetric parameters in comparison to conventional beams

Abstract

Photon beams with wide energy ranges from 4 MV to 25 MV are commonly used in radiotherapy nowadays. In recent years, there has been a strong interest in a certain modification of a radiotherapeutic apparatus by the application of the so-called flattening filter-free (FFF) beam. Several advantages of FFF beams over standard flattening filter (FF) beams are noticed, and this technical solution has aroused great interest among radiotherapeutic facilities. The goal of the present study is to investigate the differences between the conventional FF and unflattened FFF 6-MV and 10-MV photon beams in some basic dosimetric parameters and their influence on the whole radiotherapeutic treatment. The data provided here include the detailed characteristics as follows: percent depth dose (PDD), beam profile, edge of a half-profile, total scatter correction factor (TSCF) and head scatter correction factor (HSCF) for FF and FFF 6-MV and 10-MV photon beams from the Elekta Versa HD accelerator in the Katowice Oncology Center in Poland.

Open access
Comparative Review of Artificial Light Sources for Solar-Thermal Biomass Conversion Research Applications

Abstract

In recent years solar-thermal methods of waste biomass conversion are promptly gaining on attention. For researchers working in areas that suffer from lack of natural solar power, the choice of proper solar simulator for the study is crucial. Solar simulator consist of artificial light source enclosed in proper housing with optical and cooling system, powered by dedicated power supply. Solar simulators are not only granting independence from external conditions, yet provide possibility of research expand due to tuneable output power and emissive spectrum. Over the years, solar simulators were powered by different types of lamps. Throughout the history, the solar simulators were used mainly in photovoltaic and space research, crystal growth industry, and the material testing. For mentioned purposes, the total thermal output power of simulator was playing secondary role in comparison to urgent need of spectral match, irradiance distribution and beam uniformity with terrestrial or extra-terrestrial sunlight. For thermal applications, solar simulators are facing the challenge of providing high output power, described by high radiant heat flux and high heat flux density over the specified target area. In presented paper the comparison of xenon arc, metal halide lams and tungsten halogen for thermal applications has been presented with emphasis on available thermal power, spectral match with natural sunlight and operational issues. The course of decision taken during the selection of artificial light source for construction of laboratory-scale solar pyrolytic reactor is proposed.

Open access
A Comparison of ETV and LA for the Determination of Trace Elements in Solid Samples by MIP OES

Abstract

The performance of electrothermal vaporization (ETV) and laser ablation (LA) of dry aerosols as sample introduction systems for microwave induced plasma optical emission spectrometry (MIP OES) are compared and evaluated in terms of detection limits, precision and accuracy for the determination of trace elements (Ca, Cd, Cu, Fe, Mg, Mn, Sr, Zn) in the same solid micro samples. In MIP OES both radiation sources can be independently adjusted to optimize the sampling process and then its subsequent excitation. A univariate approach and simplex optimization procedure were used to obtain the best signal/noise (S/N) ratio and derive analytical figures of merit. A comparison using a Student’s t-test between the results obtained by both ETV/LA-MIP OES methods for trace elements, and concentrations in standard reference material (SRM) and certified reference materials (CRMs) showed that there was no significant differences on a 95 % confidence level. The detection limits of the tested elements in solid samples by ETV/LA-MIP OES were in the range of 0.1 to 11 µg g−1 for all elements determined, while the corresponding absolute values in the range of ng. The precision of the results for ETV-MIP OES and LA-MIP OES varied between 2 and 4 % and 3 and 7 %, respectively. The linear dynamic ranges in the ETV/LA-MIP OES are extend over three decades of concentration. The methods were validated by the analysis of NIST SRM 2711Montana Soil, NRCC CRM PACS-2 Marine Sediment and NRCC CRM TORT-2 Lobster Hepatopancreas of different matrix composition and by the standard addition technique.

Open access
Designing a Pond and Evaluating its Impact Upon Storm-Water Quality and Flow: A Case Study in Rural Australia

Abstract

Storm-water management is a common concern in rural catchments where development-related growth causes increases of storm-water flows. Greater magnitude and frequency of storm-water create greater challenges for mitigating storm-water damage and improving water quality. The concept of Blue-Green Infrastructure (BGI) as a solution incorporates a wide range of applicable components with the aim of minimizing the effect of catchment development on flow regimes without changing the watershed morphology. BGI components manage storm-water by decreasing impermeable cover and expanding natural and semi-natural systems to store water or recharge and filter storm-water into the ground. In this paper, guidelines for designing a pond as a component of BGI are provided and, configuration and size of the pond are determined. Moreover, the impacts of the designed pond on storm-water peak flow and quality are assessed for the Tarwin catchment, State of Victoria, Australia. The results indicate that the introduction of the pond would have reduced outfall inflow by 94 % and would have achieved the reduction of 88.3, 75.5 and 50.7 % for total suspended solids, total phosphorus, and total nitrogen respectively, during the extreme weather event in June 2012.

Open access
Ecological analysis of heavy metal and radioactivity potential of Holocene sediments in Iznik Lake

Abstract

In this study, the heavy metal and radioactive properties of Iznik Lake were investigated. Concentration values of the first (Ag, Bi, Mo, Sn, Se, Zn, As, B, Cd, Co, Cr, Cu, Ni, Pb, Pt and Sb) and second (Na, Mg, K, Ca, P, S, Fe, Al and Mn) group of elements in borehole 1 (BH-1) drilling did not show much variation from the top to the bottom of the drilling. Concentration values of the first group of elements in borehole 2 (BH-2) drill samples decreased at higher levels of drilling. In addition, natural and anthropogenic radionuclides were measured by gamma spectrometry, and the results of environmental natural radioactivity of Iznik Lake and its surroundings were determined. In the measurement results, Ra-226 was found to be below the world average value at all locations. It is assumed that the determination of K-40 values above the average values was due to agricultural activities carried out intensively in the study area. Th-232 values were found to be below the world average value in drilling samples; Cs-137 values were below the background level in all samples. According to these results, the study area does not contain any unnatural radioactivity.

Open access
Effect of Municipal Sewage Sludge on Soil Chemical Properties and Chemical Composition of Spring Wheat

Abstract

Municipal sewage sludge from rural sewage treatment plants is characterized by a substantial content of organic matter and macronutrients, which can be used in cultivation of cereals. In a farm located in the commune of Iwanowice in the south of Poland (Malopolska province), municipal sewage sludge was applied under spring wheat cultivation. The experiment was set up on heavy soil with slightly acid reaction and medium content of available forms of P, K, Mg. Application of sewage sludge in a dose of 23 Mg fresh matter per hectare (4.21 Mg d.m.) led to no significant changes in chemical properties of the soil. Application of sewage sludge significantly increased yield of spring wheat. That increase led to a significant decrease in the content of N, P, K, Na, Mg and Ca in spring wheat. Utilization of N, Mg, K, P and Ca from sewage sludge by spring wheat was at a level of 82, 63, 44, 36, 9 %, respectively, of the amount introduced with the waste. Application of municipal sewage sludge significantly decreased the value of Ca : P ratio in spring wheat grain and straw. The sewage sludge did not cause a significant change in the values of Ca : Mg, K : Na, K : (Ca+Mg), K : Mg and K : Ca ratios in spring wheat grain and straw. Municipal sewage sludge can be used environmentally, including for fertilization of cereals, provided that environmental standards are kept.

Open access
The effect of soil on spatial variation of the herbaceous layer modulated by overstorey in an Eastern European poplar-willow forest

Abstract

The tree species composition can influence the dynamics of herbaceous species and enhance the spatial heterogeneity of the soil. But there is very little evidence on how both overstorey structure and soil properties affect the spatial variation of the herb layer. The aim of this study is to evaluate the factors of the soil and overstorey structure by which it is possible to explain the fine-scale variation of herbaceous layer communities in an Eastern European poplar-willow forest. The research was conducted in the “Dnipro-Orils’kiy” Nature Reserve (Ukraine). The research polygon (48°30′51″N, 34°49″02″E) was laid in an Eastern European poplar-willow forest in the floodplain of the River Protich, which is a left inflow of the River Dnipro. The site consists of 7 transects. Each transect was made up of 15 test points. The distance between rows in the site was 3 m. At the site, we established a plot of 45×21 m, with 105 subplots of 3×3 m organized in a regular grid. The adjacent subplots were in close proximity. Vascular plant species lists were recorded at each 3×3 m subplot along with visual estimates of species cover using the nine-degree Braun-Blanquet scale. Within the plot, all woody stems ≥ 1 cm in diameter at breast height were measured and mapped. Dixon’s segregation index was calculated for tree species to quantify their relative spatial mixing. Based on geobotanical descriptions, a phytoindicative assessment of environmental factors according to the Didukh scale was made. The redundancy analysis was used for the analysis of variance in the herbaceous layer species composition. The geographic coordinates of sampling locations were used to generate a set of orthogonal eigenvector-based spatial variables. Two measurements of the overstorey spatial structure were applied: the distances from the nearest tree of each species and the distance based on the evaluation of spatial density of point objects, which are separate trees. In both cases, the distance matrix of sampling locations was calculated, which provided the opportunity to generate eigenvector-based spatial variables. A kernel smoothed intensity function was used to compute the density of the trees’ spatial distribution from the point patterns’ data. Gaussian kernel functions with various bandwidths were used. The coordinates of sampling locations in the space obtained after the conversion of the trees’ spatial distribution densities were used to generate a set of orthogonal eigenvector-based spatial variables, each of them representing a pattern of particular scale within the extent of the bandwidth area structured according to distance and reciprocal placement of the trees. An overall test of random labelling reveals the total nonrandom distribution of the tree stems within the site. The unexplained variation consists of 43.8%. The variation explained solely by soil variables is equal to 15.5%, while the variation explained both by spatial and soil variables is 18.0%. The measure of the overstorey spatial structure, which is based on the evaluation of its density enables us to obtain different estimations depending on the bandwidth. The bandwidth affects the explanatory capacity of the tree stand. A considerable part of the plant community variation explained by soil factors was spatially structured. The orthogonal eigenvector-based spatial variables (dbMEMs) approach can be extended to quantifying the effect of forest structures on the herbaceous layer community. The measure of the overstorey spatial structure, which is based on the evaluation of its density, was very useful in explaining herbaceous layer community variation.

Open access