Demonstrator Research Articles

Highly efficient CFRP anisogrid lattice structures for central tubes of medium-class satellites: Design, manufacturing, and performance

A design and manufacturing method for highly efficient CFRP anisogrid lattice shells aiming at central tubes for medium-class satellites is presented in the paper. Central tubes are designed to withstand high inertial forces that are induced by the supported satellite mass and equipment during the launch phase. This requires buckling and material strength other than adequate stiffness. In addition, the typical structure includes several interfaces that are subjected to significant load transfer and need to be properly integrated in the body of the shell. A specifically adapted version of the filament winding technology showed itself to be particularly suitable for this application. The modified process implements a “parallel winding” deposition strategy in conjunction with high modulus dry carbon fibers and resin infusion. However, design and manufacturing issues need to be investigated as a whole in order to minimise the structural weight and be competitive with conventional CFRP structures. In order to demonstrate the performance achievable with an optimal lattice structure, a comprehensive testing campaign was built around two full-scale prototypes: 1) the Technological Model (TM), aimed at the manufacturing process setup and mechanical properties characterization, and 2) the Demonstrator (DM), aimed at global stiffness and strength evaluations culminated with the collapse of the structure.

Sensitivity analysis of fusion power plant designs using the SYCOMORE system code

The next step after ITER is the demonstration of stable electricity production with a fusion reactor. Key design performance will have to be met by the corresponding power plant demonstrator (DEMO), fulfilling a large number of constraints. System codes such as SYCOMORE, by simulating all the fusion power plant sub-systems, address these questions. To be able to perform design optimizations, simplified models relying on physical and technological assumptions have to be used, resulting in a large number of input parameters. As these parameters are not always exactly known, the impact of their associated uncertainties on final design performance has to be evaluated. Sensitivity methods, by measuring the relative influence of inputs on the figures of merit of the design, allow the dominant parameters to be selected. This information helps the search for optimal working points, guides the priority for technical improvements and finally allows meaningful inputs for uncertainty propagation to be selected. A full set of sensitivity methods and their application to an ITER and DEMO design will be presented, discussing both the statistical method behaviours and the physical results. Plasma shape parameters (minor radius and plasma elongations) share half of the net electricity power sensitivity for the DEMO 2015 design, while the toroidal magnetic field and the 95% safety factor are responsible for 23% and 17% of the electric power sensitivity, respectively. The plasma minor radius is responsible for 45% of the pulse duration sensitivity for the DEMO 2015 design, while plasma physics parameters drive % of the pulse duration sensitivity.

The DEMO Helium Cooled Lithium Lead “advanced-plus” Breeding Blanket: Design improvement and FEM studies

In the framework of the European “HORIZON 2020” research program, the EUROfusion Consortium develops a design of a fusion demonstrator (DEMO). CEA-Saclay, with the support of Wigner-CR and IPP-CR, is in charge of one of the four Breeding Blanket (BB) concepts investigated in Europe for DEMO: the Helium Cooled Lithium Lead (HCLL) BB. The BB directly surrounding the plasma is a major component ensuring tritium self-sufficiency, shielding against neutrons from D-T plasmas and heat extraction for electricity conversion.In this article, the equatorial outboard module of the HCLL reference DEMO BB (“advanced-plus” BB) concept is studied regarding thermal and mechanical behavior during normal and accidental conditions that led to modify the design and enhance the performances. A numerical approach based on the Finite Element Method (FEM) is followed. The methodology established, the assumptions done as well as the results obtained in each case are reported and critically analysed, scrutinizing some open issues on this “advanced-plus” reference concept.

DEMO Breeding Blanket Helium Cooled First Wall design investigation to cope high heat loads

In the framework of the European “HORIZON 2020” program, EURO fusion develops a fusion power demonstrator (DEMO). According to a recent study about plasma heat loads, it appeared that the First Wall, which is the first part of the Breeding Blanket in front of the plasma, will face some high heat fluxes on some poloidal locations of the Breeding Blanket.In order to cope such high heat fluxes, this paper presents the investigation on different Helium cooled First Wall design integrated to the Breeding Blanket on the basis of standard square and circular smooth channels and with different options for the Tungsten armor surrounding the channels, taking advantages to the different material properties. The performances of the different concepts have been assessed with thermal and mechanical Finite Element Method numerical simulation based on a slice of the Helium Cooled Lithium Lead concept. Results are compared with the RCC-MRx design rules to prevent failure during normal and accidental condition. The results show that the options with channels surrounded by Tungsten could meet some plasma heat loads requirements from design point of view. However, the concept is still at an early stage of development and open issues are discussed.

Status of the EU DEMO HCLL breeding blanket design development

In the framework of the European “HORIZON 2020” innovation and research programme, the EUROfusion Consortium develops a design of a fusion power demonstrator (DEMO). One of the key components in the fusion reactor is the Breeding Blanket (BB) surrounding the plasma, ensuring tritium self-sufficiency, heat removal for conversion into electricity, and neutron shielding. CEA-Saclay, with the support of Wigner-RCP and Centrum výzkumu Řež, is in charge of the development of one of the four BB concepts investigated in Europe for DEMO: the Helium Cooled Lithium Lead (HCLL) BB. The rationales of the HCLL are the use of Eurofer as structural material, eutectic liquid lithium-lead (PbLi) as tritium breeder and neutron multiplier, and helium gas as coolant.This paper shows the basic description of the DEMO HCLL BB concept and its design evolution during the past years, from a design based on the ITER Test Blanket Module (TBM) concept to a more advanced design called “Advanced-Plus” concept. This new HCLL BB concept that has been designed in order to improve Tritium Breeding Ratio (TBR) and shielding performances is presented. This new reference HCLL BB design has been analyzed and show very promising nuclear performances. Nevertheless, the “Optimized Conservative” concept, based on ITER TBM, is still considered as a robust back-up solution since structural improvements are still necessary on the “Advanced-Plus” concept. Moreover, a new Back Supporting Structure (BSS) is presented in this paper, designed to support the BB modules, with the aim to reduce pressure drops and thermal stresses.

Nuclear analysis of the HCLL “Advanced-Plus” breeding blanket

In the frame of the European R&D effort to develop a fusion demonstrator (DEMO) a new concept of Helium Cooled Lithium Lead breeding blanket, called “Advanced-Plus” design, is studied to improve the tritium breeding. The aim of this paper is to present the nuclear analysis of this new HCLL design carried out with the TRIPOLI-4® Monte Carlo code and the Joint European Fission and Fusion nuclear data version 3.2 (JEFF-3.2). Nuclear quantities such as: neutron flux, tritium breeding ratio, nuclear heating, displacement damage and helium production are reported. Sensitivity analysis is also carried out to investigate the impact, in tritium breeding, of the next DEMO baseline with reduced outboard thickness and the advantage, in tritium production point of view, of the single module segment against the current multi-module segment option.

Investigation on the “advanced-plus” Helium Cooled Lithium Lead Breeding Blanket design concept for TBR enhancement regarding thermal and mechanical behavior

In the framework of the European “HORIZON 2020” research program, the EUROfusion Consortium develops a design of a fusion demonstrator (DEMO). The Breeding Blanket (BB) directly surrounding the plasma is a major component ensuring tritium self-sufficiency, shielding against neutrons from D-T plasmas and heat extraction for electricity conversion. CEA-Saclay, with the support of Wigner-RCP and IPP-CR is responsible of developing the Helium Cooled Lithium Lead (HCLL) BB concept. In order to enhance Tritium Breeding Ratio (TBR), an alternative HCLL BB design, called “Advanced-Plus” concept, has been investigated, with the aim to reduce the amount of steel, while ensuring good thermal and mechanical behavior. The thermal behaviors of the horizontal Stiffening Plates (hSPs) with various channels designs in terms of dimensions and layout have been parsed on simplified FE models for verifying and optimizing the HCLL Breeding Zone (BZ) before analyzing a HCLL BB ¼ model. Moreover, sensitive analyses have been carried out for testing various hSPs pitches, alternative Helium hydraulic schemes inside the hSPs as well as the detachable FW option in applying a zero Heat Flux (HF) on the FW. Furthermore, mechanical calculations have also been performed to assess the behavior of the module in faulted condition. The results obtained with the Cast3M-qualified-FEM code are presented and discussed.

Status on DEMO Helium Cooled Lithium Lead breeding blanket thermo-mechanical analyses

The EUROfusion Consortium develops a design of a fusion power demonstrator (DEMO) in the framework of the European “Horizon 2020” innovation and research program. One of the key components in the fusion reactor is the breeding blanket surrounding the plasma, ensuring tritium self-sufficiency, heat removal for conversion into electricity, and neutron shielding. The Helium Cooled Lithium Lead (HCLL) blanket is one of the concepts which is investigated for DEMO. It is made of a Eurofer structure and uses the eutectic liquid lithium–lead as tritium breeder and neutron multiplier, and helium gas as coolant. Within the EUROfusion organization, CEA with the support of Wigner-RCP and IPP-CR, is in charge of the design of the HCLL blanket for DEMO.This paper presents the status of the thermal and mechanical analyses carried out on the HCLL breeding blanket in order to justify the design. CFD thermal analyses on generic breeding unit including stiffening plates and cooling plates have been performed with ANSYS in order to consolidate results obtained with previous FEM design analyses. Moreover in order to expand the justification of the HCLL Breeding blanket design, the most loaded area of the equatorial outboard module has been analyzed with CAST3M in case of accident, according to RCC-MRx, resulting in relatively good behavior of the box. Additionally analyses have been performed in order to check the good behavior of the tie rods modules’ attachments system in normal condition showing promising results.

Acute corticosterone sexually dimorphically facilitates social learning and inhibits feeding in mice

In numerous species social learning is predominant and adaptive, yet, we know little of its neurobiological mechanisms. Social learning is modulated by motivations and emotions, in a manner that is often sexually dimorphic. Additionally, stress hormones acutely modulate the related social cognitive process of social recognition. Whether this is true even for social learning is currently unknown. We investigated the acute effects of the stress hormone corticosterone (CORT) on the social transmission of food preferences (STFP) in male and female mice. During a brief social interaction an observer (OBS) acquires a food preference from a same-sex demonstrator (DEM). CORT (1.0, 2.5, 5.0 mg/kg), its ethanol vehicle (0.1%), and saline solution (0.9%) were administered intraperitoneally to the OBS, 10 min before a 30-min social interaction. Levels of plasma CORT were assessed in other mice that had received the same doses of CORT and either had or had not gone through a 30 min social interaction 10 min post-treatment. Exogenous CORT elicited levels of plasma level comparable to those seen at the peak of the circadian cycle and facilitated the STFP with males responding more than females both in terms of the duration of the food preference and the minimum effective dose. CORT also sexually dimorphically inhibited feeding, with females showing a greater dose–response than males. Saline solution and ethanol vehicles also sexually dimorphically facilitated the STFP and reduced feeding, but less than CORT did. These results indicate that CORT facilitates social learning, like social recognition. Hence, CORT may generally increase social information processing.

Analytical models for a small LFR core dynamics studies

Analytical models for the study of a small Lead-cooled Fast Reactor (LFR) demonstrator (DEMO) core dynamics, in a control-oriented perspective, have been developed aimed at providing a useful, very flexible and straightforward tool allowing relatively quick transient design-basis and stability analyses. A simplified approach has been developed consisting in a lumped-parameter modeling of the coupled neutronics and thermal-hydraulics. The reactor transient responses following both postulated accident initiators such as Unprotected Transient of OverPower (UTOP), Loss of Heat Sink (ULOHS) and Loss of Flow (ULOF), and an emergency SCRAM event have been studied in MATLAB/SIMULINK® environment. A benchmark analysis has been then performed by means of the SAS4A/SASSYS-1 Liquid Metal Reactor Code System with the purpose of providing verification for the analytical outcomes of the nonlinear model and indicating how the latter relate to more realistic one-dimensional calculations. As a general result, responses concerning the main core characteristics (namely, power, reactivity, etc.) have turned out to be mutually consistent in terms of both steady-state absolute figures and transient developments, showing discrepancies of the order of only few per cents. DEMO dynamic behavior has been studied through a linear approach as well, so as to enable the use of linear analysis tools allowing to verify the system stability, thanks to the possibility of expressing a physical model in terms of transfer functions or state–space representation. The impact of linearization and point-kinetics one-precursor-group approximation has been further evaluated by examining the respective transient predictions, which have been compared to the nonlinear reference ones for increasing perturbations. An asymptotic stability analysis, according to Lyapunov's definition, is finally presented.

Conceptual core design study for a high-flux LFR demonstrator

A preconceptual core design study for a pool-type Lead-cooled Fast Reactor (LFR) demonstrator (DEMO) has been developed in the frame of an I-NERI between the Italian National Agency for the New Technologies, Energy and Sustainable Economic Development (ENEA) and Argonne National Laboratory (ANL), based on the European Lead-cooled System (ELSY) reference concept. A demonstration reactor is expected to prove the viability of technology to be implemented in the first-of-a-kind industrial power plant. DEMO specifications as a nuclear power facility demonstrating ELSY main features and performance, besides validating design methodology and tools, have been defined. Suitable design parameters have been set to meet the foremost objective of reaching a high fast neutron flux while respecting all technological constraints. Preliminary thermal-hydraulic analyses have been carried out to verify safety limits were not exceeded.

Dynamic performance assessment of MOX and metallic fuel core options for a Gen-IV LFR demonstrator

A preliminary study concerning the responses of a Generation IV (GEN-IV) Lead Fast Reactor (LFR) demonstrator (DEMO) core to externally-induced reactivity perturbations has been carried out with the aim at assessing and comparing the dynamic performances of MOX and metallic fuel alternative options. Reactivity coefficients and kinetics parameters have been calculated for both Beginning of Cycle (BoC) and End of Cycle (EoC) configurations by means of ERANOS deterministic code ver. 2.1 associated with the JEFF-3.1 data library. A simplified lumped-parameter model has been developed to treat both neutronics (point-kinetics approximation) and thermal-hydraulics (average temperature heat-exchange model); the latter have been then coupled to analyze MOX and metallic fuel behaviors following operational transient initiators, such as control rod partial extraction (reactivity insertion), coolant inlet temperature perturbation (simulating a loss of heat sink), and mass flow rate reduction (loss of flow), using the MATLAB/SIMULINK ® tool. The analysis of DEMO core sub-system open-loop stability has ultimately been performed. Results have shown that the model is stable and evidences a satisfactory capability of predicting the response to the reactivity perturbations considered.

Structural durability of transmission mountings from magnesium squeeze cast alloys

For the first time new promising magnesium squeeze cast alloys were investigated at the Fraunhofer Institute for Structural Durability and System Reliability (LBF) accor ding to the requirements of safety components under mi suse, special event and cyclic loading within the scope of an EU-project. This article summarises the results for structural durability relevant characteristic values obtai ned from fatigue tests under constant and variable ampli tude loading generated from specimens and the demons trator transmission mounting.

On "Hygienic Analysis," by CHARLES E. OASSAL, F.I.C.Exam., F.C.S., Public Analyst for Kensington, Senior Demon strator, Department of Hygiene, University College

On "Hygienic Analysis," by CHARLES E. OASSAL, F.I.C.Exam., F.C.S., Public Analyst for Kensington, Senior Demon strator, Department of Hygiene, University College