Comparison of the Tribological Properties of the Thermal Diffusion Zinc Coating to the Classic and Heat Treated Hot-Dip Zinc Coatings

The presented studies are focused on the wear resistance and friction coefficient changes of the thermal diffusion (TD) zinc coating deposited on steel. The aim of research was to evaluate the variation in coating properties during dry friction as a result of the method of preparation of the basis metal. The measured properties were compared to those obtained after classic hot-dip (HD) zinc galvanizing—heat treated and untreated. Thermal diffusion zinc coatings were deposited in industrial conditions (according to EN ISO 17668:2016-04) on disc-shaped samples. The results obtained during the tribological tests (T11 pin-on-disc tester) were analysed on the basis of microscopic observations (with the use of optical and scanning microscopy), EDS (point and linear) analysis and microhardness measurements. The obtained results were similar to effects observed after heat treatment of HD zinc coating. The conducted analysis proved that the method of initial steel surface preparation results in changes in the coating’s hardness, friction coefficient and wear resistance.

Comparing fast neutron transport calculations using code package KATRIN-2.0 for various options of VVER-440 core setup

Calculation of radiation exposure for VVER reactor vessel is a key task for the following determination of their burn-up life. This problem is especially topical for VVER-440 reactors of the first generation which now require substantiation report of safe operation over-designed service life. The estimation of radiation exposure of the reactor vessel involves the calculation of fast neutron fluence (E≥0.5 MeV) on welded joints and basis metal of the reactor vessel. The result of neutron fluence calculation and the associated estimation error are affected by the precision of fission neutron source definition in the reactor core. This study examines two approaches to defining fission neutron source in the fuel assembly: specifically, assembly-wise distribution, as well as rod-wise distribution approaches.The main objective of this work is to characterize the difference in calculation results of neutron fluence (E≥0.5MeV) on the VVER-440 reactor vessel at rod-wise and assembly-wise definition of the fission neutron source inperipheral fuel assemblies, and to estimate the accuracy of fluence calculation for each source definition method, bycomparing them with some experimental data. The present study examines the results of two different experiments carried out on the block of No.1 of Kola Nuclear Power Plant (V-230): each involving activity measurement for templates cut out on the internal reactor vessel surface and activity measurement of neutron-activation detectors of Niobium on the external reactor vessel surface.

Gamma-Spectrometric Determination of the Content and the Mass of Uranium Isotopes in Samples of Unknown Composition and Products of the Nuclear Fuel Cycle

The results of the uranium isotopes masses and content determination in depleted and low enriched uranium bearing samples using gamma-spectrometric data and iterative method were presented in the paper. Powders of UO2 and U3O8, compact products on their basis, metal uranium and scrap with an enrichment by the isotope 235U from 0,3 to 19,9 % were used as test samples. The sample mass ranged from tens of grams to several kilograms. Gamma-spectrometric data were processed using commercial software packages by Canberra Company: Genie 2000, MGAU, ISOCS and GeometryComposer. The proposed method provides a satisfactory correlation between the experimental and calculated data and allows estimating the quantitative characteristics (enrichment, mass of isotopes, uranium content in the matrix) of uranium bearing samples with different physical shape and chemical composition.

Chemical and microbiological changes and aerobic stability of marandu grass silages after silo opening

This trial had the objective of characterizing the microbial population and evaluating the aerobic stability of Marandu grass silages with pelleted citrus pulp (PCP). The collected forage was submitted to the following treatments: Silage of Marandu grass; silage of Marandu grass + 50 g/kg PCP and silage of Marandu grass + 100 g/kg PCP on natural matter basis. Metal cylindrical containers with 80 cm of height and 50 cm of diameter were used as silos during assays of microbiological dynamics and chemical changes of silages in anaerobiosis. Evaluations were performed on days 0, 2, 4 and 6 after silos were opened. The aerobic stability was evaluated by change in temperature, using approximately three kilograms of silage inside styrofoam boxes that were placed inside a climatic chamber. A completely randomized experimental design and split plot arrangement were used in the two assays, with five replications. Treatments were the plots and time was the subplots. Bacillus and enterobacteria were present on the Marandu grass silages with 0 g/kg PCP, which also showed pH increase throughout the feedout phase. Yeast was detected on the silages that were added with PCP. A trend of increasing temperature with extension of the aeration time was observed mainly in the silages containing 100 g/kg PCP. Isolated yeast strains showed lactate assimilation. Silages were found to be unstable due to the silo opening, both by bacterial or yeast development, which reduced the nutritional value.

Effects of the metal pollutants cadmium and nickel on soybean seed development

The chloride salts of Cd or Ni were added to the nutrient solution in which soybean (Glycine max) plants were grown and the response of the plants to these pollutants examined. Both metals markedly reduced plant biomass and seed production. Accumulation was mostly in the roots. Nickel was more mobile than Cd, reaching higher levels in all plant parts, especially seeds. Within the tissues of mature seeds, the highest concentrations of Ni were found in the axis and testa. The highest concentrations of Cd were in the testa and cotyledon, and the lowest in the axis. When expressed on a per seed basis, metal contents of these organs increased with developmental age. Nickel amounts were lower in the pods than the seeds for all growth stages, however there was no significant difference for Cd. Cadmium reduced mature seed mass. This effect was mostly due to decreased yields of lipids, protein and carbohydrates. Although the number of seeds per pod declined as a response to Ni, seed mass was unaffected and there was no apparent effect on storage reserves.