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Code assessment and validation is one of the most relevant research lines in thermal hydraulics and best estimate codes. During the last decades, the Nuclear Energy Agency (NEA) and the Organization for Economic Co-operation and Development (OECD) have sponsored dozens of experimental projects in this field. Most of them were compiled in the CSNI Code Validation Matrix in 1996. Several projects have been promoted in the new century as the SETH, PKL, PKL-2, PKL-3 and PKL-4 at the PKL test facility. In 2017 a benchmark activity was launched within the framework of the OECD/NEA PKL-4 project with the aim of assessing the capabilities of system codes to reproduce the relevant phenomena associated to the IBLOCA scenario. 16 participant organizations from 9 different countries simulated the i2.2 (run 3) experiment in semi-blind conditions. A large variety of system codes were used in the activity: ATHLET, CATHARE, KORSAR, LOCUST, RELAP5, RELAPSCDASIM, SPACE and TRACE. This paper presents the main outcomes for the code assessment of such codes. The first part describes the main features of the experiment and the selection of the key phenomena for code validation. In addition, the paper intoduces a detailed description of each phenomena and the comparison between the experimental data and the blind simulations of the participants. Finally, in the last part of the paper the main sources of uncertainty associated to the codes and the modelling are listed as well as the code assessment conclusions of the benchmark activity. In general, the results obtained by all participants showed a good performance and satisfactory agreement with experimental data, which increases the confidence in current TH code technologies. The overall quality of the contributions was partly a consequence of the excellent documentation and information provided by the PKL team.

Background: Nuclear waste management is considered amongst the major challenges in the field of nuclear energy. A possible means of addressing this issue is waste transmutation in advanced nuclear systems, whose operation requires a fast neutron spectrum. In this regard, the accurate knowledge of neutron-induced reaction cross sections of several (minor) actinide isotopes is essential for design optimization and improvement of safety margins of such systems. One such case is 240 Pu , due to its accumulation in spent nuclear fuel of thermal reactors and its usage in fast reactor fuel. The measurement of the 240 Pu ( n , f ) cross section was previously attempted at the CERN n_TOF facility EAR1 measuring station using the time-of-flight technique. Due to the low amount of available material and the given flux at EAR1, the measurement had to last several months to achieve a sufficient statistical accuracy. This long duration led to detector deterioration due to the prolonged exposure to the high a activity of the fission foils, therefore the measurement could not be successfully completed. Purpose: It is aimed to determine whether it is feasible to study neutron-induced fission at n_TOF/EAR2 and provide data on the 240 Pu ( n , f ) reaction in energy regions requested for applications. Methods: The study of the 240 Pu ( n , f ) reaction was made at a new experimental area (EAR2) with a shorter flight path which delivered on average 30 times higher flux at fast neutron energies. This enabled the measurement to be performed much faster, thus limiting the exposure of the detectors to the intrinsic activity of the fission foils. The experimental setup was based on microbulk Micromegas detectors and the time-of-flight data were analyzed with an optimized pulse-shape analysis algorithm. Special attention was dedicated to the estimation of the non-negligible counting loss corrections with the development of a new methodology, and other corrections were estimated via Monte Carlo simulations of the experimental setup. Results: This new measurement of the 240 Pu ( n , f ) cross section yielded data from 9 meV up to 6 MeV incident neutron energy and fission resonance kernels were extracted up to 10 keV . Conclusions: Neutron-induced fission of high activity samples can be successfully studied at the n_TOF/EAR2 facility at CERN covering a wide range of neutron energies, from thermal to a few MeV.

In particle physics research centers like CERN, it is critical to monitor the movements of devices inside the particle accelerator. When a technical issue in the tunnel occurs, the particle beams with high kinetic energy are sent, via two detours in the main ring, to two mainly metal absorber blocks, the so-called beam dumps, in order to stop them. The massive kinetic energy deposited on these dumps can cause them to move. Accelerometers are one measurement device that can be used to monitor the acceleration and, indirectly, the position of the dumps. In this thesis, the mechanical structure of an interferometer-based inertial accelerometer with a flexible membrane has been designed. In order to reduce the accelerator beam kinetic energy, a helical movement occurs in the particle beams, it was therefore necessary to measure the acceleration in the three spatial axes so a three-axis accelerometer is considered. As part of the theoretical approach, it was needed to focus on the requirements provided and to analyze the deformation, stress, and vibration of the structure. To ensure its reliability and precision, FEM analysis using ANSYS 19.1 was used and crosschecked by hand. After the theoretical approach, those characteristics were ensured with different types of experimental tests, such as an impact or vibration test. As a conclusion, theoretical requisites of the accelerometer have been met, except the complete linearity of the frequency response. The non-accomplishment of this requirement may lead to some error on the higher frequency acceleration measurements

Background: ß-delayed multiple neutron emission has been observed for some nuclei with A=100, being the 100Rb the heaviest ß2n emitter measured to date. So far, only 25P2n values have been determined for the ˜300 nuclei that may decay in this way. Accordingly, it is of interest to measure P2n values for the other possible multiple neutron emitters throughout the chart of the nuclides. It is of particular interest to make such a measurement for nuclei with A>100 to test the predictions of theoretical models and simulation tools for the decays of heavy nuclei in the region of very neutron-rich nuclei. In addition, the decay properties of these nuclei are fundamental for the understanding of astrophysical nucleosynthesis processes, such as the r-process, and safety inputs for nuclear reactors.

The spent fuel of current nuclear reactors contains fissile plutonium isotopes that can be combined with uranium to make mixed oxide (MOX) fuel. In this way the Pu from spent fuel is used in a new reactor cycle, contributing to the long-term sustainability of nuclear energy. However, an extensive use of MOX fuels, in particular in fast reactors, requires more accurate capture and fission cross sections for some Pu isotopes. In the case of 242Pu there are sizable discrepancies among the existing capture cross-section measurements included in the evaluations (all from the 1970s) resulting in an uncertainty as high as 35% in the fast energy region. Moreover, post-irradiation experiments evaluated with JEFF-3.1 indicate an overestimation of 14% in the capture cross section in the fast neutron energy region. In this context, the Nuclear Energy Agency (NEA) requested an accuracy of 8% in this cross section in the energy region between 500 meV and 500 keV. This paper presents a new time-of-flight capture measurement on 242Pu carried out at n_TOF-EAR1 (CERN), focusing on the analysis and statistical properties of the resonance region, below 4 keV. The 242Pu(n,gamma) reaction on a sample containing 95(4) mg enriched to 99.959% was measured with an array of four C6D6 detectors and applying the total energy detection technique. The high neutron energy resolution of n_TOF-EAR1 and the good statistics accumulated have allowed us to extend the resonance analysis up to 4 keV, obtaining new individual and average resonance parameters from a capture cross section featuring a systematic uncertainty of 5%, fulfilling the request of the NEA.

The current design of the RF power supply for the International Fusion Materials Irradiation Facility (IFMIF) is based upon tetrodes technology. Due to the improvement in the solid state amplifiers technology, the possibility of using this option for IFMIF is becoming a very competitive alternative presenting a priori several advantages in terms of availability, reliability and logistics. The current technology based on RF tetrodes chains leads no room for substantial improvements in terms of availability being the requirement for the RF system hard to achieve. On the other hand the solid state amplifiers technology opens from its concept several options to increase the system availability. The principal goals of this paper are the use of RAMI (Reliability, Availability, Maintainability and Inspectability) analysis in the RF tetrodes design to led a future work to compare the availability, reliability and logistic performances for both alternatives. The Project will consist in two parts: the development of a logistic support methodology and a specific study of the first part with an example related to the IFMIF facility. First part: Develop a systematic procedure to study the logistic support required by any component of the IFMIF facility, focusing on the component’s effect in the availability of the whole facility Second part: For the radiofrequency (RF) modules in the deuteron accelerator, study its logistic requirements and determinate the optimum quantity of the involved resources. It will comprise a research task of the requirements in the available documentation and a following task consisting in the simulation of the behaviour of the RF modules, in order to determinate the logistic support required.

EMINE master programme is an international education initiative offered by KIC-InnoEnergy under the framework of the European Institute of Innovation and Technology (EIT). Students in the programme have the opportunity to acquire an in-depth knowledge of the nuclear industry, through unique and specialised courses covering a wide range of subjects. Students choose between UPC (Barcelona) and KTH (Stockholm) for the first year and between Grenoble-INP and Paris-Saclay University (France) for the second year. Grenoble École de Management (GEM) completes the list of academic partners: students take a 3-week summer course on energy management issues after their first year in EMINE. EMINE students also benefit from the involvement of our industrial partners (AREVA, EDF, ENDESA, INSTN-CEA, and Vattenfall) in the Programme. For the academic institutions, EMINE is the opportunity to provide a high level education aligned with the industrial needs. The international collaboration among universities helps improving the quality and the adoption of best practices. EMINE attracts good students to our centres whereas the EIT funding and the industrial involvement allows a number of activities that otherwise would have been difficult to carry out, such as the assistance of external industrial experts or field activities. MSc EMINE helps tomorrow’s nuclear engineers take up the challenges the nuclear energy industry faces in terms of safety, social acceptability and waste management. By offering outstanding technical training and addressing the economic, social and political aspects of nuclear energy, the programme broadens the scope of traditional nuclear education.

Thermal-hydraulic system computer codes are extensively used worldwide for analysis of nuclear facilities by utilities, regulatory bodies, nuclear power plant designers, vendors, and research organizations. The computer code user represents a source of uncertainty that can influence the results of system code calculations. This influence is commonly known as the “user effect” and stems from the limitations embedded in the codes as well as from the limited capability of the analysts to use the codes. Code user training and qualification represent an effective means for reducing the variation of results caused by the application of the codes by different users. This paper describes a systematic approach to training code users who, upon completion of the training, should be able to perform calculations making the best possible use of the capabilities of best estimate codes. In other words, the program aims at contributing towards solving the problem of user effect. In addition, this paper presents the organization and the main features of the 3D S.UN.COP (scaling, uncertainty, and 3D coupled code calculations) seminars during which particular emphasis is given to the areas of the scaling, uncertainty, and 3D coupled code analysis.

Nonlinearities have been shown to play an important role in increasing the extracted energy of energy harvesting devices at the macro and micro scales. Vibration-based energy harvesting on the nano scale has also received attention. In this paper, we characterize the nonlinear dynamical behavior of an array of three coupled strained nanostructured graphene for its potential use in energy harvesting applications. The array is formed by three compressed vibrating membrane graphene sheet subject to external vibrational noise excitation. We present the continuous time dynamical model of the system in the form of a double-well three degree of freedom system. Random vibrations are considered as the main ambient energy source for the system and its performances in terms of the probability density function, RMS or amplitude value of the position, FFT spectra and state plane trajectories are presented in the steady state non-equilibrium regime when the noise level is considered as a control parameter.

Desarrollo de instrumentación especializada y desarrollo de algoritmos especiales capaces de interpertar las señales de medida del flujo bifásico. Combinaciones de diferentes instrumentos (Spool Piece) serán analizados y su influencia en el flujo bifásico. Outgoing

This Master Thesis has been carried out by Luis Mora Vallejo and Jacobo Zegrí Reiriz. We are both two Spanish students who are studying Engineering in the Universitat Politècnica de Catalunya (UPC) in the engineer‟s school Escola Tècnica Superior d‟Enginyeria Industrial de Barcelona (ETSEIB). This degree has got a common part the first two years and after that it is possible to be specialized in one sector of the industry. Then, we both decided to take part of the nuclear section in order to help our country in the energetics situation and also under the feeling of improvement that we are looking for ourselves. After sharing last three years in the same specialization we decided separately to carry out a Master Thesis abroad in order to obtain the Master Thesis of Science in Nuclear Engineering. However, there are a limited number of universities in the ENEN‟s network so it was necessary to have a good choice of what university would have been chosen. For many reasons we decided to work in the Politecnico di Torino and after knowing that we both were accepted we thought that it could be a good experience not only for us, but also for the Politecnico di Torino and the ETSEIB the possibility of carrying out together a complete thesis in our sector. Concerning the teamwork, it is important to say that this project is the result of the effort and the work of two people. As it will be seen in following lines, this Thesis has got some parts and although we have worked the same one has been more specialized in one than the other. For instance, whereas the theoretical part has been more summarized and searched by Jacobo, the code with Matlab has been more developed by Luis. This fact does not entail that one of the two members has made only one thing as we have been carrying out the Thesis together and both Luis and Jacobo have been working on theoretical part and Matlab respectively. Apart from that, other parts like the experimental analysis and the measurements have been developed by us at the same level and dedication because of the fact that working together it is possible to measure faster and with more precision and also it is easier to study the results and therefore to obtain conclusions as we are sharing our knowledge in this technology. The most important objectives that are pursued in this Thesis are related with the analysis of a horizontal air-water flow. It would be interesting to obtain an experimental and theoretical characterization of a horizontal flow using different evaluations, theories and analysis such as flow pattern analysis, pressure drop evaluations, void fraction evaluation and mass flow rate measurements. In order to achieve our goal the Department of Energetics (DENER) of the Politecnico di Torino has put at our disposal several offices, computers, software and facilities to work at our Thesis. Concerning the experimental system, which we have been working with, it will be accurately explained on next chapters. However, it can be said that it contains the necessary devices to develop our tasks related to the measurements in a correct and safety way. This Thesis is not only an analysis about the data obtained as it is also necessary to carry out a deep research work because of the difficulty of working on two-phase flow and also because of the length of the field. The experimental part consists on taking a large number of data to know, after all measurements with laboratory devices, the properties of the mixture which is flowing through a pipe only with the knowledge of some parameters. So it could be said that the aim of this work is to define an appropriate theoretical and experimental methodology that can be used in experimental apparatus, able to simulate the thermohydraulic of Nuclear Power Plant in steady state and accident (LOCA) conditions, in order to measure two-phase flow quantities as mass flow rates and velocities of water and vapour. Outgoing

Les aplicacions de l'energia nuclear per a usos bèllics durant la Segona Guerra Mundial van donar lloc a l'aparició d'una nova tecnologia: l'enginyeria nuclear. Aquesta nova branca de l'enginyeria va ser poc difosa durant els anys de la postguerra per raons de seguretat militar i, per això, no va tenir una repercussió immediata en l'ensenyament fins la dècada dels cinquanta. Aquesta comunicació analitza els factors que van contribuir a la introducció de l'enginyeria nuclear en el currículum de l'enginyer en un país perifèric agafant com a exemple el cas de l'Escola Tècnica Superior d'Enginyeria de Barcelona., The applications of nuclear energy for military proposes during World War II gave rise to a new technology: nuclear engineering. This new branch of engineering was restricted during the post-war period for military reasons and, therefore, did not form part of the engineering courses until the 1950s. This paper analyses the factors that contribute to the introduction of nuclear engineering to the engineering curriculum at the School of Industrial Engineers of Barcelona.

High statistics samples of reconstructed charmed particles have been obtained by the NA14' experiment. Signals are presented in a variety of decay channels, and are used for the measurement of lifetimes and the study of production mechanisms.

In this work we study the phenomenological consequences of the environment dependence of neutrino mass on solar and reactor neutrino phenomenology. Such dependence can be induced, for example, by Yukawa interactions with a light scalar particle which couples to neutrinos and matter and it is expected, among others, in mass varying neutrino scenarios. Under the assumption of one mass scale dominance, we perform a global analysis of solar and KamLAND neutrino data which depends on 4 parameters: the two standard oscillation parameters, Delta m^2 and tan^2(theta), and two new coefficients, which parameterize the environment dependence of the neutrino mass. We find that, generically, the inclusion of the environment dependent terms does not lead to a very statistically significant improvement on the description of the data in the most favoured MSW LMA (or LMA-I) region. It does, however, substantially improve the fit in the high-Delta m^2 LMA (or LMA-II) region which can be allowed at 98.9% CL. Conversely the analysis allow us to place stringent constraints on the size of the environment dependence terms, which can be translated on a bound on the product of the effective neutrino-scalar (lambda^\nu) and matter-scalar (lambda^N) Yukawa couplings, as a function of the scalar field mass (m_S) in these models., Comment: final version to appear in Phys.Rev.D

The 241Am(n,¿ ) cross section has been measured at the n_TOF facility at CERN with the n_TOF BaF2 Total Absorption Calorimeter in the energy range between 0.2 eV and 10 keV. Our results are analyzed as resolved resonances up to 700 eV, allowing a more detailed description of the cross section than in the current evaluations, which contain resolved resonances only up to 150–160 eV. The cross section in the unresolved resonance region is perfectly consistent with the predictions based on the average resonance parameters deduced from the resolved resonances, thus obtaining a consistent description of the cross section in the full neutron energy range under study. Below 20 eV, our results are in reasonable agreement with JEFF-3.2 as well as with the most recent direct measurements of the resonance integral, and differ up to 20–30% with other experimental data. Between 20 eV and 1 keV, the disagreement with other experimental data and evaluations gradually decreases, in general, with the neutron energy. Above 1 keV, we find compatible results with previously existing values.