Impact of activation cross-section uncertainties on the tritium production in the HFTM specimen cells

The prediction of the tritium production is required for handling procedures of samples, safety & maintenance and licensing of the International Fusion Materials Irradiation Facility (IFMIF). A comparison of the evaluated tritium production cross-sections with available experimental data from the EXFOR data base has shown insufficient validation. And significant discrepancies in evaluated cross-section libraries, including lack of tritium production reactions for some important elements, were found. Here, we have addressed an uncertainty analysis to draw conclusions on the reliability of the tritium prediction under the potential impact of activation cross-section uncertainties. We conclude that there is not sufficient experimental validation of the evaluated tritium production cross-sections, especially for iron and sodium. Therefore a dedicated experimental validation program for those elements should be desirable

Understanding Charge Transfer in Donor-Acceptor/Metal Systems: A Combined Theoretical and Experimental Study

We develop an effective potential approach for assessing the flow of charge within a two-dimensional donor-acceptor/metal network based on core-level shifts. To do so, we perform both density functional theory (DFT) calculations and x-ray photoemission spectroscopy (XPS) measurements of the core-level shifts for three different monolayers adsorbed on a Ag substrate. Specifically, we consider perfluorinated pentacene (PFP), copper phthalocyanine (CuPc) and their 1:1 mixture (PFP+CuPc) adsorbed on Ag(111).Comment: 12 pages, 10 figure

Do teachers believe that video games can improve learning?

Although video games are increasing their presence in teens/children's private entertainment and there is ample evidence to support their educational possibilities, they are seldom introduced in classrooms. One of the least studied factors relative to the insertion of video games in curricula is teachers' conceptions on their effectiveness to foster learning. In this study, we investigate how teachers conceive of the educational usage of video games, considering their reported value and which video game dimensions are reflected to be of importance, as well as personal traits linked to them (gender, educational level, area of knowledge, teaching experience, behavioral intention ...). We designed a Likert questionnaire with three main dimensions: pragmatic play, epistemic play, and learning outcomes (verbal information, skills, and attitudes). 595 Spanish teachers answered the questionnaire online. We applied ANOVA and multiple regression techniques, which revealed a broad acceptance of video games as educational media. The most relevant analyzed factors turned out to be the intention to use video games in classrooms, and the private use of video games. Teachers believe that video games promote more learning when played with an epistemic goal, mediated by scaffolding and especially under the teacher's guidance, compared to pragmatic play related to completion and success in the game. They also consider video games to mainly promote verbal information learning, procedural learning, and finally attitude learning, with the latter being less probable. We suggest the need to strengthen not only teacher training programs in the educational use of video games but also research on relationships between teachers' beliefs and practices in order to convert these favorable beliefs into actual real practicesThis research was supported by Ministerio de Ciencia e Innovacion of Spain [PID2020-114177RB-I00

A passive available bandwidth estimation methodology

The Available Bandwidth (AB) of an end-to-end path is its remaining capacity and it is an important metric for several applications such as overlay routing and P2P networking. That is why many AB estimation tools have been published recently. Most of these tools use the Probe Rate Model, which requires sending packet trains at a rate matching the AB. Its main issue is that it congests the path under measurement. We present a different approach: a novel passive methodology to estimate the AB that does not introduce probe traffic. Our methodology, intended to be applied between two separate nodes, estimates the path’s AB by analyzing specific parameters of the traffic exchanged. The main challenge is that we cannot rely on any given rate of this traffic. Therefore we rely on a different model, the Utilization Model. In this paper we present our passive methodology and a tool (PKBest) based on it. We evaluate its applicability and accuracy using public NLANR data traces. Our results -more than 300Gb- show that our tool is more accurate than pathChirp, a state-of-the-art active PRM-based tool. At the best of the authors’ knowledge this is the first passive AB estimation methodology.Preprin

Nuclear data requirements for the ADS conceptual design EFIT: Uncertainty and sensitivity study

In this paper, we assess the impact of activation cross-section uncertainties on relevant fuel cycle parameters for a conceptual design of a modular European Facility for Industrial Transmutation (EFIT) with a “double strata” fuel cycle. Next, the nuclear data requirements are evaluated so that the parameters can meet the assigned design target accuracies. Different discharge burn-up levels are considered: a low burn-up, corresponding to the equilibrium cycle, and a high burn-up level, simulating the effects on the fuel of the multi-recycling scenario. In order to perform this study, we propose a methodology in two steps. Firstly, we compute the uncertainties on the system parameters by using a Monte Carlo simulation, as it is considered the most reliable approach to address this problem. Secondly, the analysis of the results is performed by a sensitivity technique, in order to identify the relevant reaction channels and prioritize the data improvement needs. Cross-section uncertainties are taken from the EAF-2007/UN library since it includes data for all the actinides potentially present in the irradiated fuel. Relevant uncertainties in some of the fuel cycle parameters have been obtained, and we conclude with recommendations for future nuclear data measurement programs, beyond the specific results obtained with the present nuclear data files and the limited available covariance information. A comparison with the uncertainty and accuracy analysis recently published by the WPEC-Subgroup26 of the OECD using BOLNA covariance matrices is performed. Despite the differences in the transmuter reactor used for the analysis, some conclusions obtained by Subgroup26 are qualitatively corroborated, and improvements for additional cross sections are suggested

In vivo genotoxicity and inflammatory effects of uncoated and coated CeO2 NPs in mice

P17-045 Ceria nanoparticles (CeO2 NPs) have several industrial applications and pharmacological potential due to their antioxidant properties. However, toxicity data on CeO2 NPs are scarce and show contradictory results. In the present study, uncoated, polyethylene glycol- and citrate-coated CeO2 NPs (4-8 nm) were administrated to C57Bl/6 mice by repeated dose (3×) pharyngeal aspiration using four different doses of each type of NPs (corresponding to 4.4, 8.8, 17.6 and 35.2 µg Ce2+/mouse/aspiration), and sampled 1 and 28 days after the last administration. DNA damage was assessed by the comet assay locally in bronchoalveolar lavage (BAL) and lung cells, and systemically in liver cells. Micronuclei, a biomarker of chromosome damage, were analysed in bone marrow and peripheral blood erythrocytes. Immunotoxicity was evaluated by BAL cell counting. Furthermore, histopathological effects on the lungs and biodistribution of the NPs (analysis of Ce2+ in several organs) were assessed. At 24-h, a significant increase in DNA damage was induced at the highest doses by uncoated and citrate-coated NPs in BAL cells. For these NPs a significant, but non-dose-dependent, effect was observed in lung and liver cells at 28-d. No systemic genotoxic effects were observed with any of the NPs. A dose-dependent accumulation of macrophages and activated lymphocytes was seen in the lungs for all the NPs, although a milder reaction was elicited by the coated NPs. Our findings show that short-term exposure of mice to CeO2 NPs induces pulmonary inflammation, and non-dose-dependent DNA damage, but no systemic genotoxicity. (Funded by the EU FP-7 GUIDEnano, Grant Agreement No.604387)

Sensitivity/Uncertainty Analysis for BWR Configurations of Exercise I-2 of UAM Benchmark

In order to evaluate the uncertainties in prediction of lattice-averaged parameters, input data of core neutronics codes, Exercise I-2 of the OECD benchmark for uncertainty anal-ysis in modeling (UAM) was proposed. This work aims to perform a sensitivity/uncertainty analysis of the BWR configurations defined in the benchmark for the purpose of Exercise I-2. Criticality calculations are done for a 7x7 BWR fresh fuel assembly at HFP in four configurations: single unrodded fuel assembly, rodded fuel assembly, assembly/reflector and assembly in a color-set. The SCALE6.1 code package is used to propagate cross section covariance data through lattice physics calculations to both k-effective and two-group assembly-homogenized cross sec-tions uncertainties. Computed sensitivities and uncertainties for all configurations are analyzed and compared. It was found that uncertainties are very similar for the four test-problems, showing that the influence of the assembly environment on uncertainty prediction is very small