Fuel burnup of the JSI TRIGA was calculated by simulating complete operational history consisting of 240 different core configurations from 1966 to 2020. At the moment we are unable to perform burnup ...measurements, e.g. gamma spectroscopy on burned fuel elements, hence we used weekly measured excess reactivity as a reference point of different core configurations to verify the calculated core reactivity. Changes in reactivity due to burnup were assumed to be linear and this assumption was verified for burnup intervals smaller than 3
MWd
/
kg(HM)
. The comparison was performed on 46 different core configurations with different type of fuel elements. The Serpent-2 calculations decently predict the rate of reactivity change on different cases, as 52 % of calculations are withing 1
σ
and 86.9 % within 2
σ
of the measurements for total number of 46 cases. Additional analysis was performed by comparing unit cell calculations of different fuel types. Four different types of TRIGA fuel were used to analyse burnup changes in LEU and HEU fuel, where positive reactivity feedback on burnup was observed for HEU fuel due to burnable absorbers. Serpent-2 and WIMSD-5B were compared on unit-cell basis where good agreement within 200 pcm of reactivity change for large burnup was observed. In addition neutron spectrum changes due to burnup were investigated using unit-cell calculations where 4 % increase of the thermal peak and 1 % decrease of fast peak of the spectrum was observed for typical fuel burnups of 20
MWd
/
kg(HM)
, which approximately represents JSI TRIGA burnup at this moment.
The Triglav Glacier in the Julian Alps and the Skuta Glacier in the Kamnik-Savinja Alps are among the south-easternmost glaciers in the Alps. Historical data show that ice masses are undergoing mass ...loss as the overall climate warms. Glacier ice and cave ice contain a wealth of paleoclimatic information, and rapid sampling is needed if any such information is to be saved before the ice is completely melted. We present the first comprehensive geochemical and water isotope data from glacier ice, meltwater, spring water, and cave ice in the Mount Triglav area and glacier ice from the Skuta Glacier. The samples primarily reflect the initial precipitation signal that has been greatly modified by the input of local CaCO3-rich dust with lesser amounts of marine aerosol and vegetation debris.
The retreat of ice shelves and glaciers over the last century provides unequivocal evidence of recent global warming. Glacierets (miniature glaciers) and ice patches are important components of the ...cryosphere that highlight the global retreat of glaciers, but knowledge of their behaviour prior to the Little Ice Age is lacking. Here, we report the uranium–thorium age of subglacial carbonate deposits from a recently exposed surface previously occupied by the disappearing Triglav Glacier (southeastern European Alps) that may elucidate the glacier's presence throughout the entire Holocene. The ages suggest the deposits' possible preservation since the Last Glacial Maximum and Younger Dryas. These thin deposits, formed by regelation, are easily eroded if exposed during previous Holocene climatic optima. The age data indicate the glacier's present unprecedented level of retreat since the Last Glacial Maximum and the potential of subglacial carbonates as additional proxies to highlight the extraordinary nature of the current global climatic changes.
We collected a sediment core from the 6th (6J) Triglav Lake, a remote mountain lake in NW Slovenia, and analysed it for 25 elements, using
k
0
-instrumental neutron activation analysis (
k
0
-INAA). ...For Hg, we used cold vapour atomic absorption spectrometry (CVAAS). Data were analysed using Principal Component Analysis (PCA). PCA indicated several distinct groups of elements and sediment core samples. Ca distribution was entirely different from all other sediment components. Ba, Br, Hg, Sb and Zn were associated with organic matter (OM), with Hg showing the strongest affinity to OM. As, Cr, Fe and U formed a group of redox-sensitive elements. Two events that occurred ca. 1915 and in the 1940s/1950s, were identified in the core. They were associated with increased inputs of allochthonous material into the lake, and significantly affected the stratigraphic distributions of all elements. Some trace elements, such as As, Hg and Zn, are probably effectively retained in the catchment, whereas Cr tends to be readily exported from the catchment. Atmospheric deposition affected not only elements of anthropogenic origin (As, Ba, Br, Hg, Sb, Zn and Cr) that started to increase after the 1970s, but also those of terrestrial origin (Ca, Fe, Na). Introduction of fish into the lake in 1991 and the subsequent increase in primary production, affected the distribution of Ca and elements that are redox-sensitive and/or associated with OM (As, Ba, Fe, Sb, U, Zn). Fe minerals in uppermost 6J sediments have a strong influence on the distribution of several trace elements. As and Zn closely tracked Fe, whereas Sb was likely released after oxidation. Climate change could also have enhanced inputs of elements from the catchment, but such changes were likely overwhelmed by the effects of increased eutrophication.
Various ice bodies are an important source of paleoenvironmental data, and their study improves the understanding of present and future environmental conditions. Their changes are an important ...indicator of climate change. This special issue of Acta geographica Slovenica draws attention to the changing and disappearing cryosphere across the globe, with an emphasis on the southeastern Alps, and the necessity to conduct research in this field before the ice disappears forever. This paper briefly summarizes the current body of knowledge on glaciers, permafrost, cave ice, lake and river ice, and snow in the southeastern Alps, and it presents the contribution of Acta geographica Slovenica to this research and the main highlights of all five papers included in this special issue.
In this study, analysis of the complete operational history of the “Jožef Stefan” Institute (JSI) TRIGA reactor was performed. Reactor power changes, core configurations and weekly excess reactivity ...measurements were analysed to obtain the needed data for fuel burnup calculations. More than 50 years of reactor operation was simulated using deterministic code TRIGLAV and stochastic code Serpent-2. The calculated core reactivities are in good agreement compared with the excess reactivity measurements. Code-to-code comparison is presented. Clear agreement is observed when comparing changes in core excess reactivity, and discrepancies are observed in the comparison of individual fuel element burnup and its isotopic composition. The Serpent-2 results are in better agreement with the measurements compared to the TRIGLAV code; nevertheless, a conclusion can be made that the TRIGLAV code is viable for TRIGA fuel management and burnup analysis. A three-dimensional (3D) burnup study was conducted, where individual fuel elements were further divided into multiple angular and axial depletion zones. Notable burnup effects were observed, and an explanation using surrounding water distance is presented.
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Acidophytic alpine mat-grass swards are rare in the alpine belt of the predominantly calcareous Southeastern Alps of Slovenia, mostly occurring where limestone is admixed with marlstone or chert. ...Those for which we were able to make phytosociological relevés can be classified mainly into two syntaxa:
and
. At slightly lower elevations, in the forest zone of the subalpine plateau Pokljuka, we found similar swards occupying small areas in frost hollows with luvisol on limestone. They include character species of various subalpine-alpine sward and snow bed communities and are classified into the syntaxon
The Tale of Zlatorog speaks of a human-nature interrelationship, close to today’s environmentalism. It has been highly popular in Slovenia and abroad since collected in the Julian Alps and published ...in 1868. In the first part of this paper, we investigate the Triglav rose, particularly, which real plant species might be reflected in the story. In the second part, we compare the drama with real processes in ecosystems. As reflected in the narrative, humans did not only recognize creatures’ supporting roles: they comprehended the interconnectedness that sustains life and survival. While tales acted as the inspiration for ethical teaching, we assume that artists used the dynamics developed in the Tale of Zlatorog and alike for transferring the reverence for life and sustaining biocentric ethics.
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