Search

In this contribution, new data concerning the distribution of vascular flora alien to Italy are presented. It includes new records, confirmations, exclusions, and status changes for Italy or for Italian administrative regions. Furthermore, three new combinations are proposed. Nomenclatural and distribution updates published elsewhere are provided as Suppl. material 1.

In this contribution, the conservation status assessment of four vascular plants according to IUCN categories and criteria are presented. It includes the assessments of Aurinialeucadea (Guss.) K.Koch, Chondrillachondrilloides (Ard.) H.Karst., Daphnecneorum L., and Ophioglossumazoricum C.Presl at regional level (Italy).

TRANSURANUS is a computer program for the thermal and mechanical analysis of fuel rods irradiated in nuclear reactors. It was originally developed at the Institute for Transuranium Elements (ITU), now Joint Research Centre (JRC) Karlsruhe, and is currently used worldwide by universities, research centers, technical safety organizations, safety authorities and industrial partners. The TRANSURANUS code consists of a clearly defined mechanical–mathematical framework into which physical models can easily be incorporated. The code is able to deal with a wide range of different irradiation situations, i.e., normal, off-normal and accidental conditions (e.g., design basis accidents, such as reactivity-initiated accidents or loss of coolant accidents), in thermal as well as fast spectrum reactors. The code covers both wide time and spatial scales (from milliseconds to years of irradiation, from the fuel grain to the fuel pin) that are necessary to accurately simulate various inter-connected intra-granular phenomena which are of high relevance at the engineering scale of the integral fuel pin. The code relies on a comprehensive built-in material data bank for oxide, mixed oxide, carbide and nitride fuels, zircaloy and steel claddings, and several different coolants (light water, liquid sodium, liquid potassium, helium, liquid lead and lead–bismuth). It can be applied in two different modes—in a deterministic orstatistical mode—allowing for assessing the impact of experimental and model uncertainties via incorporation of a Monte Carlo technique. The mathematical methods and solvers implemented in the code support its modification and extension, while providing excellent numerical stability. After details about the structure of the code and embedded models, the present Chapter provides examples of validation of TRANSURANUS against irradiation experiments and application to reactor safety analyses, showing the applicability of the code for simulating various kind of irradiations of fuel pins in both thermal water-cooled and fast liquid metal-cooled reactors. While confirming the code capabilities in predicting the fuel pin behaviour in water reactor conditions, which has been the main application of TRANSURANUS over the last three decades, the presented results are a good basis for the extension and validation of the code for MOX fuels in a fast reactor environment, becoming more and more important in the framework of Generation IV reactors development.

Invasive alien plants are a major threat to biodiversity and they contribute to the unfavourable conservation status of habitats of interest to the European Community. In order to favour implementation of European Union Regulation no. 1143/2014 on invasive alien species, the Italian Society of Vegetation Science carried out a large survey led by a task force of 49 contributors with expertise in vegetation across all the Italian administrative regions. The survey summed up the knowledge on impact mechanisms of invasive alien plants in Italy and their outcomes on plant communities and the EU habitats of Community Interest, in accordance with Directive no. 92/43/EEC. The survey covered 241 alien plant species reported as having deleterious ecological impacts. The data collected illustrate the current state of the art, highlight the main gaps in knowledge, and suggest topics to be further investigated. In particular, the survey underlined competition as being the main mechanism of ecological impact on plant communities and Natura 2000 habitats. Of the 241 species, only Ailanthus altissima was found to exert an ecological impact on plant communities and Natura 2000 habitats in all Italian regions; while a further 20 species impact up to ten out of the 20 Italian administrative regions. Our data indicate that 84 out of 132 Natura 2000 Habitats (64%) are subjected to some degree of impact by invasive alien plants. Freshwater habitats and natural and semi-natural grassland formations were impacted by the highest number of alien species, followed by coastal sand dunes and inland dunes, and forests. Although not exhaustive, this research is the first example of nationwide evaluation of the ecological impacts of invasive alien plants on plant communities and Natura 2000 Habitats.

Introduction/Background High-grade serous ovarian carcinoma (HGSOC), the most common and deadly epithelial ovarian cancer histotype is characterized by a heterogeneous genomic landscape. After surgery, all patients are treated with adjuvant platinum (Pt)-based chemotherapy to which the response is heterogeneous, ranging from cases sensitive (Platinum-sensitive, Pt-s cases), to intrinsically resistant patients, who relapse within 6 months from the end of therapy (Pt-resistant, Pt-r). The aim of the study was to investigate the mechanisms characterizing the biology of primary resistance to upfront Pt-based chemotherapy through an integrated pathway analysis. Methodology Gene and miRNA microarray experiments were carried out on 36 Pt-s and 41 Pt-r tumor samples. Gene and miRNA expression have been integrated using Micrographite algorithm. Expression levels of selected predictive and prognostic genes were validated on a total of 242 HGSOC samples by qRT-PCR and on the Curated Ovarian Database (including 838 HGSOC). Results Expression profiles of 131 mRNAs and five miRNAs, belonging to five different and functionally-related molecular pathways, discriminate Pt-s and Pt-r cases. We selected 23 elements of the networks for orthogonal validation and 19 coding genes confirmed as differentially expressed between Pt-r and Pt-s cases. Among them, 16 elements also showed independent prognostic value in terms of PFS and OS in multivariate analysis. The prognostic impact of this signature was in silico validated on the Curated Ovarian Database, resulting in a 3-gene signature as independent prognostic biomarker of survival for HGSOC. Conclusion In the current study, we used an integrated pathway analysis on miRNA and gene expression signatures to capture the key pathways shaping the different biology of Pt-r and Pt-s tumors, validating our results using two independent cohorts of HGSOC biopsies. Finally, we investigated the association of the validated signature with survival across multiple HGSOC databases. This strategy identified a three-gene signature with predictive and prognostic impact in HGSOC. Disclosure Nothing to disclose

Following the Fukushima-Daiichi accident in 2011, the Council Directive 2014/87/Euratom has reinforced the previous 2009 Directive that had established a Community framework for the safety of nuclear installations. In particular, one new article introduces a high-level EU-wide safety objective of preventing accidents through defence-in-depth and avoiding radioactive releases outside a nuclear installation. For achieving this objective, the research necessary outcomes are mainly a better knowledge of the involved physical phenomena and its capitalization in methodologies and tools such as simulation codes. ETSON, the European Technical Safety Organisation Network, had already identified in its Position Paper in 2011 the main R&D priorities. The present paper underlines that most of these priorities, with a few updates due to progress of knowledge, remain consistent with the objectives of this new Directive. And it illustrates the ETSON involvement through examples of on-going or planned R&D national and international projects.

In this contribution, new data concerning the distribution of vascular flora alien to Italy are presented. It includes new records, and confirmations for Italy or for Italian administrative regions of taxa in the genera Albizia, Anredera, Bougainvillea, Cardamine, Cenchrus, Cephalaria, Ceratochloa, Cytisus, Datura, Delosperma, Euonymus, Freesia, Hylotelephium, Lantana, Musa, Physalis, Rotala, Styphnolobium, Trachycarpus, and Tradescantia. Nomenclature and distribution updates, published elsewhere, and corrections are provided as supplementary material.

Conservation of Leucojum aestivum, a wetland-dependent species distributed in Europe and west Asia, should aim to reduce the fragmentation of wild stands, through the establishment of new populations. However, density-dependent dynamics occur in L. a estivum. For instance, fruit set and seed set increase with increasing plant density. In this study, we evaluate the effect of plant density on translocation success of two recently established populations of L. a estivum. Twenty-six populations of L. a estivum were investigated in northern Italy to find out differences in population traits (size, density, age structure, and reproductive performance) between populations from different habitats. Data obtained were used to establish two new populations of the species differing for population density (high H, mirroring the typical plant density of a wild population in Salix alba woods and low L, in which plant density was halved compared to H), to evaluate the role of density-dependent dynamics on the translocation success. 4 years after the translocation, H produced seedlings, while L did not. Moreover, H produced a significantly higher number of fruits per fruiting plant and higher fruit set. Seed set was also greater in H than in L, while mortality was greater in L than in H, but differences were not significant. Our results suggest that population density is an important factor to account for in newly established populations, especially in those species showing density-dependent population dynamics. Moreover, the imitation of successful within-population dynamics occurring in natural stable populations may increase the translocation success.

Following the Fukushima-Daiichi accident, many countries decided to strengthen the safety systems of their nuclear power plants in order to increase the capabilities of managing severe nuclear accidents. To achieve this goal detailed analysis of postulated design and beyond-design-basis accidents is essential. The main tools available for the analysis of these complex scenarios are Advanced Lumped Parameters (LP) and Computational Fluid Dynamics (CFD) codes. Currently, the most limiting factor in the application of these tools is their validation. This activity is performed in support of the development and validation of a CFD model, built in the numerical environment of OpenFOAM, for hydrogen behavior in the containment of Light Water Reactors. For validation purpose, numerical simulations of the erosion of a light gas stratification by means of a hot air jet have been performed, and results of the simulations were analysed and compared against experimental results obtained by Ritterath (2012) in the MiniPanda facility. Two different scenarios have been considered, each characterized by a different value of the mass flow rate of the jet used to erode the stratification.

In this contribution new data concerning the distribution of native vascular flora in Italy are presented. It includes new records, exclusion, extinction and confirmations to the Italian administrative regions for taxa in the generaAndrosace,Artemisia,Fragaria,Melampyrum,Myosotis,Petrorhagia,Phillyrea,Rosa,Rumex,Spiranthes,Trifolium, andVicia. Furthermore, a new combination in the genusOmalothecais proposed.

Ambrosia is an annual anemophilous weed producing allergenic pollen affecting public health in European countries. In Italy, the most infested region is Lombardy where, in some areas, it is the major cause of hay fever. In the Parma district, until 2007, Ambrosia seemed to be very rare, despite an observed increase of Seasonal Pollen Index (SPI), of pollen peak value and of asthma among ragweed sensitized patients. The aims of this study were to calculate ragweed pollen season and trends from 1996 to 2015, to assess the relationships between pollen season characteristics and selected meteorological data, to map plants in the territory and to evaluate the presence of beetle Ophraella communa (Ophraella), known as an eater of Ambrosia leaves.The following pollination parameters: start, end, duration, peak concentration date, peak values, SPI and the following climatic parameters: temperature, relative humidity, rainfall, were analyzed. The ragweed plants sites were mapped and the presence of Ophraella was assessed during naturalistic activities.Significant SPI and pollen peak value increase until 2011 were observed, but recently, 2012-2015 vs 2009-2011, a strong reduction (about 50%) of these parameters was observed. The spring average air temperature increased significantly. The results of the correlation analysis showed Ambrosia season characteristics significantly related. We identified the sites source of Ambrosia, even downtown at the confluence between Parma and Baganza rivers. Ophraella was observed for the first time in 2014.The results showed the spread of ragweed plants over the territory and the risk of allergy increase that ragweed could cause. It remains to evaluate the role of the Ophraella in the reduction of Ambrosia pollen concentration. It is important to consider the potential risk Ophraella may represent for sunflower and other taxonomically related crop plants and other native and exotic species. The lack of initiatives by the Health Authorities to prevent and to contrast the spread of Ambrosia in the Parma area could cause public health consequences and an increase in health expenditures.

The spread of the invasive and allergenic Ambrosia artemisiifolia L. in Italy was analysed and mapped using distribution data from a wide range of sources. Ambrosia artemisiifolia occupies 1057 floristic quadrants which are mostly distributed in the Po plain. The distribution obtained represents the basis to implement urgent management strategies.

In this contribution new data concerning the distribution of native vascular flora in Italy are presented. It includes new records, exclusions, and confirmations to the Italian administrative regions for taxa in the generaAsplenium,Bolboschoenus,Botrychium,Chamaerops,Crocus,Galeopsis,Grafia,Helosciadium,Hieracium,Juniperus,Leucanthemum,Lolium,Medicago,Phalaris,Piptatherum,Potamogeton,Salicornia,Salvia,Seseli,Silene,Spiraea,TorilisandVicia.Rhaponticoidescalabricais proposed assynonym novumofR.centaurium. Furthermore, new combinations in the generaGalatellaandLactucaare proposed.

During the normal operation of a Light Water Reactor (LWR), the fuel–cladding gap may close, as a result of several phenomena and processes, including different thermal expansion and swelling of both the fuel and the cladding (Pellet Cladding Interaction – PCI). In this equilibrium state, a significant increase of local power (like a transient power ramp in the order of 100 kW/m h), induces circumferential stresses in the cladding. In presence of corrosive fission products (i.e. iodine) and beyond specific stress threshold depending on the material, cracks typical of stress corrosion may appear and grow-up (stress corrosion cracking – SCC). These cracks may spread out from the cladding internal surface, causing the fuel failure. Investigations on fuel behavior are carried out in close connection with experimental research, operation feedback and computational analyses. To address the issue of PCI/SCC, the “BWR Inter-Ramp Project” is investigated by means of TRANSURANUS code. The BWR Inter-Ramp Project is part of the OECD/NEA International Fuel Performance Experiments database. It provides the experimental data of 20 BWR fuel rods during power ramp. The objective was to establish the failure-safe operating limits of representative BWR fuel rods when subjected to power ramp tests after short to medium irradiation time. The burn-up ranges from 10 to 20 MWd/kgU. The aim of the activity is to compare, investigate and summarize the main outcomes achieved after the simulations of 20 Zircaloy-2 – UO 2 rods of various types and designs by TRANSURANUS code. Focus is given to the main variables, which are involved or may influence the simulation of cladding failure and characterize the power ramp tests. Sensitivity analyses are carried out to address the relevance of the knowledge of the boundary conditions, as well as the impact of selected parameters and code options on the simulations. The analyses bring to the conclusion that the code may under-estimate the pellet gaseous swelling (and consequently the cladding failures), of six fuel rods that experienced low power cycles at 10 MWd/kgU. The failure propensity of the remaining fourteen rods is conservatively simulated.

The paper deals with the evaluation of the Fukushima-Daiichi Nuclear Power Plant (NPP) accident in Units 1 to 4: an attempt is made to discuss the scenario within a technological framework, considering precursory documented regulations and predictable system performance. An outline is given at first of the NPP layout and of the sequence of major events. Then, plausible time evolutions of relevant quantities in the different Units, is inferred based on results from the application of numerical codes. Scenarios happening in the primary circuit and containment (three Units involved) are distinguished from scenarios in spent fuel pool (four Units involved). Radiological releases to the environment and doses are approximately estimated. The event is originated by a natural catastrophe with almost simultaneous occurrence of earthquake and tsunami. These caused heavy destruction in a region in Japan much wider than the land around the NPP which was affected by the nuclear contamination. Key outcome from the work is the demonstration of strength for nuclear technology; looking at the past, misleading Probabilistic Safety Assessment (PSA) data and inadequacy in licensing processes have been found. Looking into the future keywords are Emergency Rescue Team (ERT), Enhanced Human Performance (EHP), and Robotics in Nuclear Safety and Security (RNSS).

In this contribution, new data concerning the Italian distribution of native vascular flora are presented. It includes new records, exclusions, and confirmations pertaining to the Italian administrative regions for taxa in the genera Arundo, Bromopsis, Cistus, Crocus, Festuca, Galeopsis, Genista, Lamium, Leucanthemum, Nerium, Orobanche, Peucedanum, Pilosella, Polycnemum, Stipa and Viola.

In this contribution, new data concerning the Italian distribution of alien vascular flora are presented. It includes new records, exclusions and confirmations for Italy or for Italian administrative regions for taxa in the genera Ageratum, Aster, Buddleja, Cedrus, Centranthus, Cephalotaxus, Clerodendrum, Cotoneaster, Cyperus, Honorius, Lantana, Ligustrum, Morus, Muscari, Oenothera, Opuntia, Platycladus, Plumbago, Pseudotsuga, Sedum, Sporobolus, Stachys, Ulmus and Yucca. A nomen novum, Stachys talbotii, is proposed as a replacement name for Sideritis purpurea.

The OECD/NEA Sandia Fuel Project provided unique thermal-hydraulic experimental data associated with Spent Fuel Pool (SFP) complete drain down. The study conducted at Sandia National Laboratories (SNL) was successfully completed (July 2009 to February 2013). The accident conditions of interest for the SFP were simulated in a full scale prototypic fashion (electrically heated, prototypic assemblies in a prototypic SFP rack) so that the experimental results closely represent actual fuel assembly responses. A major impetus for this work was to facilitate severe accident code validation and to reduce modeling uncertainties within the codes. Phase I focused on axial heating and burn propagation in a single PWR 17 × 17 assembly (i.e. “hot neighbors” configuration). Phase II addressed axial and radial heating and zirconium fire propagation including effects of fuel rod ballooning in a 1 × 4 assembly configuration (i.e. single, hot center assembly and four, “cooler neighbors”). This paper summarizes the comparative analysis regarding the final destructive ignition test of the phase I of the project. The objective of the benchmark is to evaluate and compare the predictive capabilities of computer codes concerning the ignition testing of PWR fuel assemblies. Nine institutions from eight different countries were involved in the benchmark calculations. The time to ignition and the maximum temperature are adequately captured by the calculations. It is believed that the benchmark constitutes an enlargement of the validation range for the codes to the conditions tested, thus enhancing the code applicability to other fuel assembly designs and configurations. The comparison of lumped parameter and CFD computer codes represents a further valuable achievement.

RELAP5 is a system code developed at the Idaho National Environmental and Engineering Laboratory for thermal hydraulic analysis of nuclear reactors. The code RELAP5 is widely used for safety analysis studies of commercial nuclear power plants. However, recent released version of RELAP5/3.2 and over present significant capabilities for analysis of nuclear reactor research systems. As a contribution to the assessment of RELAP5/3.3 for research reactor safety analysis, experimental data from the University of Massachusetts Lowell Research Reactor - UMLRR are used. The UMLRR is a 1 MW light water moderated and cooled, graphite-reflected, open-pool type research reactor. This paper presents the development and the validation of a UMLRR-RELAP model using experimental data. For this purpose, a series of experiments were performed for benchmarking RELAP5 calculations for research reactor systems. As a result of this study, the UMLRR nodalization is shown to be representative of the experimental data reactor behavior.

Valutazione dello stato di conservazione di Viola elatior Fries per la Lista Rossa della Flora vascolare e crittogamica Italiana

The main aim of the following study is to perform a safety analysis of the IAEA 10 MW MTR Pool type Research Reactor [IAEA-TECDOC-233, 1980. IAEA Research Reactor Core Conversion from the use of high-enriched uranium to the use of low enriched uranium fuels Guidebook] under flow blockage of a single Fuel Assembly (FA) conditions. Such event was rarely investigated in the open literature notwithstanding the fat that it constitutes a severe accident that may lead to local dryout and eventually to loss of the FA integrity. The transients herein considered are related to partial and total obstruction of the cooling channel of a single Fuel Assembly of the reactor core. This study constitutes the first step of a larger work, which consists in performing a 3D simulation using the Best Estimate coupled code technique. However, as a first approach the instantaneous reactor power is derived through the point kinetic approach of the used thermal-hydraulic system code.

We studied the habitat characteristics in a number of Cryptogramma crispa stations throughout the Alps. Our objectives were: (1) to define the environmental ecology of C. crispa in the southern part of its distributional area in Europe; (2) to test the reliability of ecological indicator values of soil reaction, nutrient and dispersion status, light and temperature for this species. The habitats of C. crispa mostly consisted in coarse-grained stable screes (on rock slide deposits, talus cones, talus sheets, stone fields and moraines), within a broad elevation range with maximum frequency in the subalpine and lower alpine vegetation belts. At higher altitudes, C. crispa was mostly found on South-exposed slopes with high potential irradiance, whereas at low altitude it was most abundant on North-exposed rather gentle slopes formed of big boulders. The screes colonized by C. crispa were formed of acid metamorphic rocks or igneous rocks and had a coarse texture. The soil accumulated in the spaces among boulders had sandy texture and acidic reaction, with medium to high carbon and total nitrogen contents. Calcium lacks entirely in the soil. Our field data gave support to the Ellenberg–Landolt ecological indicator values of light and temperature, but not to those of soil reaction and soil nutrient content, for which some changes are proposed.

The safety evaluation of nuclear power and re search reactors is a very important step before their construction and during their operation. This evaluation based on the best estimate calculations requires qualified codes qualified users, and qualified nodalizations. The effect of code users on the RELAP5 results during the analysis of loss of flow transient in MTR research reactors is presented in this pa per. To clarify this effect, two nodalizations for research reactor different in the simulation of the open water surface boundary conditions of the reactor pool have been used. Very different results are obtained with few choices for code users. The core natural circulation flow with the be ginning of core boiling doesn't stop but in creases. The in creasing in the natural circulation flow shifts out the boiling from the core and the clad temperature decreases be low the local saturation temperature.

Nowadays, increased attention to safety issues for nuclear research reactors has emerged as a consequence of their enlarged commercial exploitation. Almost all of the research reactors safety analyses were, so far, performed using conservative computational tools. Currently, the application of Best-Estimate methods constitutes a real necessity in order to get a more realistic vision of the system behavior, and overcome constraining limits related to conservative approaches. The aim of the current work is an attempt to apply this technique using the system thermal-hydraulic RELAP5/Mod3.2 code. For this purpose, the IAEA 10 MW MTR pool type research reactors Benchmark problem is considered. The exercise consists in performing some fast transients related to typical reactivity induced accidents, and relatively slow transients related to loss of flow accidents. The RELAP5 results were compared against previous data obtained by various conservative channel codes. Differences between the two modeling approaches are afterwards emphasized and discussed. � 2004 Elsevier Ltd. All rights reserved.

We're physically deploying a network of thousands of sensor nodes across the campus. Recent advances in wireless communication and sensor and actuator technologies have given rise to new genre of ubiquitous systems. We design middleware that can provide network connectivity in a decentralized fashion and use of a decentralized self-organizing infrastructure to improve the availability of today's ubiquitous networks.

Licensing requirements vary by country in terms of their scope, range of applicability and numerical values and may imply the use of system thermal hydraulic computer codes. Depending on the specific event scenario and on the purpose of the analysis, it might be required the availability of calculation methods that are not implemented in the standard system thermal hydraulic codes, as for burst temperature, burst strain and flow blockage calculations. This may imply the use of a dedicated fuel rod thermo-mechanical computer code, which can be coupled with thermal-hydraulic system and neutron kinetic codes to be used for the safety analysis. This paper describes the development and the application of a methodology for the analysis of the Large Break Loss of Coolant Accident (LB-LOCA) scenario in Atucha-2 Nuclear Power Plant (NPP), focusing on the procedure adopted for the use of the fuel rod thermo-mechanical code and its application for the safety analysis (Chapter 15 Final Safety Analysis Report, FSAR). The methodology implies the application of best estimate thermal-hydraulic, neutron physics and fuel pin performance computer codes, with the objective to verify the compliance with the specific acceptance criteria. The fuel pin performance code is applied with the main objective to evaluate the extent of cladding failures during the transient. A strong effort has been performed in order to enhance the fuel behaviour code capabilities and to improve the reliability of the code results.

The OECD/NEA PSB-VVER project provided unique and useful experimental data for code validation from PSB-VVER test facility. This facility represents the scaled-down layout of the Russian-designed pressurized water reactor, namely, VVER-1000. Five experiments were executed, dealing with loss of coolant scenarios (small, intermediate, and large break loss of coolant accidents), a primary-to-secondary leak, and a parametric study (natural circulation test) aimed at characterizing the VVER system at reduced mass inventory conditions. The comparative analysis, presented in the paper, regards the large break loss of coolant accident experiment. Four participants from three different institutions were involved in the benchmark and applied their own models and set up for four different thermal-hydraulic system codes. The benchmark demonstrated the performances of such codes in predicting phenomena relevant for safety on the basis of fixed criteria.

Depending on the specific event scenario and on the purpose of the analysis, it might be required the availability of calculation methods that are not implemented in the standard system thermal hydraulic codes. This may imply the use of a dedicated fuel rod thermo-mechanical computer code. This paper provides an outline of the methodology for the analysis of the 2A LB-LOCA accident in Atucha-2 NPP and describes the procedure adopted for the use of the fuel rod thermo-mechanical code. The methodology implies the application of best estimate thermal-hydraulic, neutron physics and fuel pin performance computer codes, with the objective to verify the compliance with the specific acceptance criteria. The fuel pin performance code is applied with the main objective to evaluate the extent of cladding failures during the transient. The procedure consists of a deterministic calculation by the fuel performance code of each individual fuel rod during its lifetime and in the subsequent LB-LOCA transient calculations. The boundary and initial conditions (e.g. pin power axial profiles) are provided by core physics and three dimensional neutron kinetic coupled thermal-hydraulic system codes (RELAP5-3D©) calculations. The procedure is completed by the sensitivity calculations and the application of the probabilistic method, with the aim of a better understanding of the uncertainties involved and their technological consequences on the behavior of the fuel rods, not addressed in the current paper.

Accurate simulation of transient system behavior of a nuclear power plant is the goal of systems code calculations, and the evaluation of a code's calculation accuracy is accomplished by assessment and validation against appropriate system data. These system data may be developed either from a running system prototype or from a scaled model test facility, and characterize the thermal hydraulic phenomena during both steady state and transient conditions. The identification and characterization of the relevant thermal hydraulic phenomena, and the assessment and validation of thermal hydraulic systems codes, has been the objective of multiple international research programs. The validation and assessment of the best estimate thermal hydraulic system code TRACE against the Multi-Application Small Light-Water Reactor (MASLWR) Natural Circulation (NC), helical coil Steam Generator (SG), Nuclear Steam Supply System (NSSS) design is a novel effort, and is the topic of the present paper. Specifically, the current work relates to the assessment and validation process of TRACE code against the NC database developed in the OSU-MASLWR test facility. This facility was constructed at Oregon State University under a U.S. Department of Energy grant in order to examine the NC phenomena of importance to the MASLWR reactor design, which includes an integrated helical coil SG. Test series have been conducted at this facility in order to assess the behavior of the MASLWR concept in both normal and transient operation and to assess the passive safety systems under transient conditions. In particular the test OSU-MASLWR-002 investigated the primary system flow rates and secondary side steam superheat, used to control the facility, for a variety of core power levels and Feed Water (FW) flow rates. This paper illustrates a preliminary analysis, performed by TRACE code, aiming at the evaluation of the code capability in predicting NC phenomena and heat exchange from primary to secondary side by helical SG in superheated condition and to evaluate the fidelity of various methods to model the OSU-MASLWR SG in TRACE. The analyses of the calculated data show that the phenomena of interest of the OSU-MASLWR-002 test are predicted by the code and that one of the reasons of the instability of the superheat condition of the fluid at the outlet of the SG is the equivalent SG model used to simulate the different group of helical coils. The SNAP animation model capability is used to show a direct visualization of selected calculated data.

The fuel matrix and the cladding constitute the first barrier against radioactive fission product release. Therefore a defense in depth concept requires also the comprehensive understanding of fuel rod behavior and accurate prediction of the lifetime in normal operation and in accident condition as well. Investigations of fuel behavior are carried out in close connection with experimental research operation feedback and computational analyses. In this connection, OECD NEA sets up the “public domain database on nuclear fuel performance experiments for the purpose of code development and validation - International Fuel Performance Experiments (IFPE) database”, with the aim of providing a comprehensive and well-qualified database on UO2 fuel with Zr cladding for model development and code validation. This database includes the data set of the Studsvik Inter-Ramp BWR Project. The objectives of the project are to establish the failure-safe operating limits and the failure mechanism and associated phenomena, during power ramp tests, by varying the design parameters (i.e. cladding heat treatment, gap thickness and fuel density). The experimental data are used for the assessment of the Fission Gas Release (FGR) models implemented in the TRANSURANUS code versions “v1m1j07” and “v1m1j08”. The starting point of the activity is the availability of a “new” transient fission gas release model, the “TFGR model”, specifically implemented in the last code version, to cover power ramp conditions. The paper presents the complete set of simulations of all twenty rods irradiated in the R2 research reactor and the corresponding comparisons with the experimental data. Sensitivity calculations are also performed to address the influence of geometric parameters and the choice of the different code options, relevant to model the FGR, on results.

Investigations of fuel behavior are carried out in close connection with experimental research, operation feedback and computational analyses. OECD NEA sets up the “International Fuel Performance Experiments (IFPE) database”, a public domain database on nuclear fuel performance experiments with the purpose of model development and code validation. The objective of the activity (performed in the framework of the IAEA CRP FUMEX-III project) is to investigate the pellet–clad interaction mechanism and the capability of TRANSURANUS code in simulating the phenomena, processes occurring in the fuel rod during the power ramps, with focus on the parameters influencing the cladding failures. The experimental database adopted is the Studsvik PWR Super-Ramp subprogram, part of the IFPE database, which consists of 28 pressurized water reactor fuel rods power ramped at burnup from 28 to 45 MWd/kgU. Relevant results by TRANSURANUS are presented in connection with the experimental evidences. Focus is given on the PCI/SCC failure, demonstrating that the failure threshold, available in TRANSURANUS, results conservative both in case of KWU and W rods.

The success of a software system strongly depends on the ability of turning a precise domain analysis into a concrete architecture. Even if the domain model relies on sound ontological bases, there is often a wide semantic gap between the conceptual model and the concrete components that should reify it. To fill the semantic gap, relevant domain concepts should be engineered by identifying the corresponding architectural abstractions, which can be realized by concrete software components. Space plays a crucial role in many application domains, but surprisingly, related architectural abstractions have not emerged yet. This paper proposes space-related abstractions derived from the application of classical software engineering principles; in particular, the information hiding principle that leads to an operational definition of space. Basic abstractions are refined to deal with architectural aspects. As the underlying software engineering principles are close to principles that underlie the definition of space ontologies, the conjecture is that the proposed space architectural abstractions might be the basis for a formalization in ontological terms.

The development of an improved process for decentralised combined heat and power generation from biomass gasification was the main goal of this project. Based on gasification tests performed in a b ...

The goal of the MAIS system is to provide support for flexible and adaptive execution of applications in a distributed, multichannel, mobile information system. In such a system, a fundamental requirement is an ability to describe the continuously evolving execution environment and user characteristics. Service requests are therefore satisfied by considering both the request itself and its provisioning environment. The first part of this chapter presents the general architecture of the MAIS system. The MAIS architecture allows us to define a set of “pluggable” modules which can be composed to provide adaptivity at different levels in the MAIS system. The main architectural components are introduced in Sect. 2.2; more details of the components are provided in the rest of the book. The MAIS reference framework, illustrated in the second part of this chapter, provides the essential basis for all of the adaptive mechanisms that are illustrated in the book. The MAIS reference framework defines a common understanding of the elements of a mobile information system that are used to enable communication among the various modules of a MAIS system during information exchange and service provisioning. The reference framework is composed of a set of models: the functional model, the architectural model, and the context model. These are described in the second part of this chapter.

The wide diffusion of mobile devices and the increasing availability of wireless networks claim applications able to adapt their behaviour with respect to the running context. This paper presents Dynamic Adaptive Navigation (DAN), a novel approach that may be exploited to build context-aware information systems. DAN provides the user with different navigation modalities. The observation of QoS features concerning the users, the devices, and the network drive the selection of the actual navigation modality that is intended as the best available. The navigation modalities are modelled via graphs describing the synthesis/expansion process that must be performed on the information. Applications to be adaptive, either implicitly or explicitly, rely on the reflection paradigm. Since DAN may be used to build adaptive applications, it should rely on reflective mechanisms too. DAN exploits the reflection mechanisms provided by the MAIS (Multichannel Adaptive Information System) architecture. Indeed, MAIS provides via reflective classes the visibility of the QoS-related aspects of the underlying system objects. Finally, to verify the usefulness of the ideas, DAN approach has been chosen to develop a new version of PDBudget, a system that supports the academic administration in analysing and evaluating the didactic workload for each lecturer at the University of Milano-Bicocca.

The overall goal of the MAIS framework is to support services that are capable of adapting their behavior to changing requirements, environments, user profiles and platforms, in order to provide the user with a suitable quality of service (QoS) [112, 181, 292]. To accomplish this goal, both the front-end and the back-end MAIS environment exploit knowledge about the architecture and configuration of the underlying platform. By platform we mean of all the hardware and software system objects that support the services, for example computing nodes, interaction devices, software components and communication networks. Applications usually rely on abstractions that expose the functional aspects of the system objects. For instance, an application can display something, or send a request through a communication service. System objects also exhibit non functional aspects: in particular, basic QoS features such as bandwidth, availability, screen size, memory size, and battery level [23, 246]. Such features are subject to changes, the rate of which can go from static (e.g., the screen size of a user device) to highly dynamic (e.g., the transfer rate of a network service). In any case, the QoS of the system objects are unknown when the software components that implement the services are being developed. Therefore, in order to provide an adaptive service, such components must be capable of observing and (if possible) of controlling the QoS of the system objects they rely on [24, 25, 26]. Unfortunately, QoS is usually hidden from high-level software components. Sometimes it can be managed via tricky low-level mechanisms. In any case, there are no high-level abstractions that allow an object's QoS to be observed and controlled by high-level, platform-independent software components. To fill this gap, the MAIS project exploits a reflective architecture. The architecture is "reflective" because it allows high-level software components to observe and control the features and the inner state of the system itself. System objects are modeled by meta objects (reflective objects, or R Objects, see [251]) which expose, at a suitable level of abstraction, their meaningful features in terms of QoS. System objects and R Objects are causally connected [241]. The existence of a causal connection means that a state change in the system object causes a state change in the corresponding R Object, and vice versa. Figure 4.1 shows the various layers of the reflective system, in accordance with the general scheme sketched in Fig. 2.6. Functional objects model the functional and non reflective aspects of system objects, as exposed by the technological layer; for instance, a screen is an object where applications can display images. Reflective objects, on the other hand, model the non functional and QoS-related aspects of the system objects; for instance, a screen is modeled by its size, resolution and so on. The figure shows how the reflective mechanisms can be exploited in various ways, which will be discussed in the rest of this chapter. (Figure presented) Reflective applications rely on both domain-specific and reflective knowledge in order to provide adaptive services. Such applications exploit both functional and reflective objects. For instance, a reflective application (Reflective Application B in Fig. 4.1) can exploit both domain knowledge (e.g., user profiles) and reflective knowledge (e.g., QoS features of the devices exposed by the base reflective layer via Base R Objects) in order to provide the end user with an "optimal" service. The base reflective layer is discussed in Sect. 4.2. This approach allows sophisticated solutions to be devised, although they imply that software developers must be aware of the low-level QoS features of the underlying platform. To reduce this drawback, the extended reflective layer provides mechanisms for defining suitable QoS strategies that provide the visibility of extended R Objects. Such objects expose to the applications (Reflective Application A in Fig. 4.1) the QoS of the system objects at a higher level of abstraction. The extended reflective layer is discussed in Sect. 4.3. Reflective middleware is an intermediate tier that exploits reflective knowledge to provide applications with enhanced functional objects (i.e., functional objects with a better QoS). Non stationary distributed systems, i.e. systems where different parts exhibit great diversity in terms of message transfer delays, provide a difficult background for traditional two-tier architectures. In order to provide QoS, such as reliability and availability, for such systems we envisage the use of a three-tier architecture for service replication, where reflective middleware (i.e., an extended reflective layer) is interposed between the client layer and the end tier. The goal of this middle tier is to limit the scope of agreement protocols to well behaved parts of the system (where the middle and end tiers are located), thus relieving non reflective applications from the burden of such protocols. The three-tier scheme is represented on the right side of Fig. 4.1, where the middle tier exploits reflective knowledge to provide applications with the visibility of enhanced functional objects with improved QoS. This approach relieves the applications from the management of non functional issues, although the middle tier is bound to implement best effort policies that do not exploit domain specific knowledge. The three tier scheme for replication is discussed in Sect. 4.4. A simple example may help us to understand the two approaches. Assume that a back-end application generates a streaming video towards a front-end device. If the application itself is reflective, it can observe the QoS in detail via the appropriate R Objects and, possibly, the topology of the underlying communication subsystem as well. Therefore the application may either adapt itself to the available bandwidth (for instance, by tuning the compression rate) or control, whenever possible, the QoS of the communication subsystem (for instance, by choosing an alternate communication path). This allows the application to exploit domain knowledge (for instance, by choosing the communication path according to the requirements exposed by the user profile), at the price of a higher complexity. On the other hand, a reflective middleware layer can be interposed between the base reflective layer and the application. It would be in charge of exploiting some best-effort strategy (for instance, by choosing a communication path) in order to provide the application with a suitable QoS. The application would be simpler, as it would not have to manage reflective issues. The drawback is that the strategies implemented by the reflective middleware cannot exploit specific domain knowledge (for instance, the user profile). The proposed mechanisms can be exploited by higher-level software components, which are denoted in Fig. 4.1 as applications. In this perspective, the higher level components that implement the MAIS framework can be viewed as applications, even if they should more properly be viewed as middleware components. Section 4.2 recalls the concepts related to the computational reflection, and presents the base reflective layer. Section 4.3 describes the extended reflective layer. Section 4.4 discusses the three-tier model for replication. Finally, Section 4.5 sketches two application examples

The main aim of the following study is to perform a safety analysis of the IAEA 10 MW MTR Pool Type Research Reactor [1]. The reactor is core cooled and moderated by downward forced circulation of light water. The transient herein considered is the related to partial and total obstruction of a single Fuel Assembly (FA) cooling channel. Such event constitutes a severe accident for this type of reactor since it may lead to local dryout and eventually to loss of the FA integrity. Two cases are analysed to emphasize the severity of the accident. The first one is a partial blockage of a single FA considering four different obstruction levels: 50%, 75%, 85% and 95% of nominal flow area. The second one is an extreme scenario consisting of total blockage of the same FA. This study constitutes the first step of a larger work which consists in performing a 3D simulation using the Best Estimate coupled code technique. However, as a first approach the instantaneous reactor power is derived through the point kinetic calculation.Copyright © 2004 by ASME

Allium cyrilli was long misinterpreted by Italian botanists and often confused with other taxa. In order to fix the application of this name, a lectotype is selected. The taxonomy of this species is clarified and discussed, especially in relation to the similar A. nigrum . Moreover, the distribution data of A. cyrilli in Italy are significantly updated, since the species is newly recorded for northern Italy (Piedmont, Emilia-Romagna and Veneto). The most useful qualitative and quantitative morphological characters, aimed to distinguish this species, are highlighted.