Multiphysics Optimization for First Wall Design Enhancement in Water-Cooled Breeding Blankets

The commercial feasibility of the first fusion power plant generation adopting D-T plasma is strongly dependent upon the self-sustainability in terms of tritium fuelling. Within such a kind of reactor, the component selected to house the tritium breeding reactions is the breeding blanket, which is further assigned to heat power removal and radiation shielding functions. As a consequence of both its role and position, the breeding blanket is heavily exposed to both surface and volumetric heat loads and, hence, its design requires a typical multiphysics approach, from the neutronics to the thermo-mechanics. During last years, a great deal of effort has been put in the optimization of the breeding blanket design, with the aim of maximizing the tritium breeding and heat removal performances without undermining its structural integrity. In this paper, a derivative-free optimization method named “Complex method” is applied for the design optimization of the European DEMO Water-Cooled Lithium Lead breeding blanket concept. To this purpose, a potential performances-based objective function, focusing on the maximization of the tritium breeding, is defined and a multiphysics numerical model of the blanket is developed in order to solve the coupled thermo-mechanical problem, while the optimization algorithm leads the design towards a minimum optimum point compliant with the prescribed requirements. Once the optimized design is obtained, its nuclear and thermo-structural performances are assessed by means of specific neutron transport and multiphysics simulations, respectively. Finally, the structural integrity is verified by means of the application of the RCC-MRx design criteria

Remote device access in the new accelerator controls middleware

This paper presents the Remote Device Access (RDA) package developed at CERN in the framework of the joint PS/SL Controls Middleware project. The package design reflects the Accelerator Device Model in which devices, named entities in the control system, can be controlled via properties. RDA implements this model in a distributed environment with devices residing in servers that can run anywhere in the controls network. It provides a location-independent and reliable access to the devices from control programs. By invoking the device access methods, clients can read, write and subscribe to device property values. We describe the architecture and design of RDA its API, and CORBA-based implementations in Java and C++. First applications of RDA in the CERN accelerator control systems are described as well

Modelling sorption thermodynamics and mass transport of n-hexane in a propylene-ethylene elastomer

Optimization of post polymerization processes of polyolefin elastomers (POE) involving solvents is of considerable industrial interest. To this aim, experimental determination and theoretical interpretation of the thermodynamics and mass transport properties of POE-solvent mixtures is relevant. Sorption behavior of n-hexane vapor in a commercial propylene-ethylene elastomer (V8880 Vistamaxx™ from ExxonMobil, Machelen, Belgium) is addressed here, determining experimentally the sorption isotherms at temperatures ranging from 115 to 140 °C and pressure values of n-hexane vapor up to 1 atm. Sorption isotherms have been interpreted using a Non Random Lattice Fluid (NRLF) Equation of State model retrieving, from data fitting, the value of the binary interaction parameter for the n-hexane/V8880 system. Both the cases of temperature-independent and of temperature-dependent binary interaction parameter have been considered. Sorption kinetics was also investigated at different pressures and has been interpreted using a Fick’s model determining values of the mutual diffusivity as a function of temperature and of n-hexane/V8880 mixture composition. From these values, n-hexane intra-diffusion coefficient has been calculated interpreting its dependence on mixture concentration and temperature by a semi-empiric model based on free volume arguments

A Bootstrapped Modularised method of Global Sensitivity Analysis applied to Probabilistic Seismic Hazard Assessment

Probabilistic Seismic Hazard Assessment (PSHA) evaluates the probability of exceedance of a given earthquake intensity threshold like the Peak Ground Acceleration, at a target site for a given exposure time. The stochasticity of the occurrence of seismic events is modelled by stochastic processes and the propagation of the earthquake wave in the soil is typically evaluated by empirical relationships called Ground Motion Prediction Equations. The large uncertainty affecting PSHA is quantified by defining alternative model settings and/or model parametri-zations. In this work, we propose a novel Bootstrapped Modularised Global Sensitivity Analysis (BMGSA) method for identifying the model parameters most important for the uncertainty in PSHA, that consists in generating alternative artificial datasets by bootstrapping an available input-output dataset and aggregating the individual rankings obtained with the modularized method from each of those.The proposed method is tested on a realistic PSHA case study in Italy. The results are compared with a standard variance-based Global Sensitivity Analysis (GSA) method of literature. The novelty and strength of the proposed BMGSA method are both in the fact that its application only requires input-output data and not the use of a PSHA code for repeated calculations

Advanced methods for loss-of-flow accident precursors identification in a superconducting magnet cryogenic cooling circuit

In nuclear fusion systems, such as ITER, Superconducting Magnets (SMs) will be employed to magnetically confine the plasma. A Superconducting Magnet Cryogenic Cooling Circuit (SMCCC) must keep the SMs at cryogenic temperature to preserve their superconductive properties. Thus, a Loss-Of-Flow Accident (LOFA) in the SMCCC is to be avoided. In this work, a three-step methodology for the prompt identification of LOFA precursors (i.e., those component failures leading to a LOFA) is developed. First, accident scenarios are randomly generated by Monte Carlo sampling of the SMCCC components failures and the corresponding transient system response is simulated by a deterministic thermal-hydraulic code. In this phase, fast-running Proper Orthogonal Decomposition (POD)based Kriging metamodels, adaptively trained to mimic the behavior of the detailed long-running code, are employed to reduce the associated computational burden. Second, the scenarios generated are grouped by a Spectral Clustering (SC) embedding the Fuzzy C-Means (FCM), in order to characterize the principal patterns of system evolution towards abnormal conditions (e.g., a LOFA). Third, an On-line Supervised Spectral Clustering (OSSC) approach is developed to assign signals measured during plant operation to one of the prototypical clusters identified, which may reveal the corresponding LOFA precursors (in terms of combinations of failed SMCCC components). The devised method is applied to the simplified model of a cryogenic cooling circuit of a single module of the ITER Central Solenoid. Results show that the approach developed timely identifies 95% of LOFA events and approximately 80% of the corresponding precursors

Response to measles, mumps and rubella (Mmr) vaccine in transfusion-dependent patients

Measles, mumps and rubella (MMR) still determine significant morbidity and mortality, although a highly effective vaccine is available. Postponing the MMR vaccination until 6 months after the last red blood cell (RBC) transfusion is recommended, but this delay is incompatible with chronic transfusions. The present study aimed at investigating the impact of blood transfusions on the immunogenicity of the MMR vaccine. In this observational study, a group of 45 transfusion-dependent (TD) patients was compared to 24 non-transfusion-dependent (NTD) patients. Immunity to measles was achieved in 35 (78%) TD and 21 (88%) NTD subjects (p = 0.7), to mumps in 36 (80%) TD and 21 (88%) NTD subjects (p = 0.99), and to rubella in 40 (89%) TD and 23 (96%) NTD subjects (p = 0.99). No significant difference was observed in the number of non-immune individuals or those with doubtful protection between the two groups (p > 0.05). The mean IgG value, assayed in 50 pre-storage leukoreduced RBC units, was 0.075 ± 0.064 mg/mL, ten times lower than the level assumed in blood units and considered detrimental to the immune response in TD patients. This work shows a favorable response to MMR vaccination in TD and NTDT patients and paves the way for further larger studies assessing the impact of chronic transfusions on vaccine response

post hoc analysis of clarinet phase iii study to investigate the influence of diabetic status on progression free survival pfs of patients with neuroendocrine tumours nets treated with lanreotide lan or placebo pbo

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Skeletochronology, age at maturity and cause of mortality of loggerhead sea turtles Caretta caretta stranded along the beaches of Campania (south-western Italy, western Mediterranean Sea)

Information on demographic and life-history traits of endangered vertebrate species, such as sea turtles, is crucial for planning management and conservation actions. We applied skeletochronology of phalanges to estimate the age of loggerhead turtles, Caretta caretta, found dead stranded along the beaches of Campania (western Mediterranean) from 2013 to 2017. To obtain maturity data, we examined gonads from a subsample of 7 males and 11 females. Overall, curved carapace length (CCL) ranged from 5.6 to 90.8 cm, but for most turtles (89%) it was 50-79.9 cm. Predominance of stranded females (62%) was recorded. Ten out of the eighteen histologically examined gonads allowed estimating maturity. Based on the lines of arrested growth counting, the estimated age of the examined specimens ranged from 0 (hatchling) to 26 years. The modal age was 14 years for males and 17 years for females. The smallest male with spermatogenetic activity had a CCL of 65 cm and was estimated to be 16 years old. The smallest female with follicular development stage, characterising the transition towards adulthood, had a CCL of 69.5 cm and was estimated to be 20 years old. Anthropogenic factors were responsible for 36% of the mortality of individuals, followed by parasitic/infective pathologies (20%). Copyright Fabio Maria Guarino et al