Search results for "Nuclear energy"
showing 10 items of 614 documents
Updated design and integration of the ancillary circuits for the European Test Blanket Systems
2019
The validation of the key technologies relevant for a DEMO Breeding Blanket is one of the main objectives of the design and operation of the Test Blanket Systems (TBS) in ITER. In compliance with the main features and technical requirements of the parent breeding blanket concepts, the European TBM Project is developing the HCLL (Helium Cooled Lithium Lead) and HCPB (Helium Cooled Pebble Bed)-TBS, focusing in this phase on the design life cycle and on R&D activities in support of the design. The TBS ancillary systems are mainly circuits devoted to the removal of thermal power and to the extraction and recovery of the tritium generated in the Test Blanket Modules. They are: • The Helium C…
Consolidated design of the HCPB Breeding Blanket for the pre-Conceptual Design Phase of the EU DEMO and harmonization with the ITER HCPB TBM program
2020
Abstract From 2014 to 2020, the Pre-Conceptual Design phase (PCD) of the EU DEMO has taken place. The activities in the PCD phase differ from past exercises in their strong Systems Engineering methodology, as well as for the pragmatic approach in their technology choices. The Helium Cooled Pebble Bed (HCPB) is one of the 2 candidates as driver blanket for the EU DEMO in the PCD phase. Several design iterations have been required during the PCD phase in order to adjust the design to the current demanding DEMO requirements, to the very challenging systems integration and to the need to keep near-term technologies. To this respect, the design has evolved to a so-called fuel-breeder pin archite…
Key EU DEMO plant and building layout criteria
2021
Abstract An early attention to the layout of both plant site and its buildings is essential in a complex plant under preliminary design as DEMO in order to meet the assigned targets, namely i) the licensing requirements ii) a good availability in delivery electricity to the grid. The layout definition has to follow several criteria that become more complex and stringent for nuclear buildings, e.g. functional, maintenance, fire protection, safety, human factors, shielding, and remote handling. The criterion As Low As Reasonable Achievable, with respect to the dose to the staff, has to be applied in design, operation, maintenance and decommissioning phases. The tokamak building, where several…
Ab initio modeling of oxygen impurity atom incorporation into uranium mononitride surface and subsurface vacancies
2011
The incorporation of oxygen atoms has been simulated into either nitrogen or uranium vacancy at the UN(001) surface, sub-surface or central layers. For calculations on the corresponding slab models both the relativistic pseudopotentials and the method of projector augmented-waves (PAW) as implemented in the VASP computer code have been used. The energies of O atom incorporation and solution within the defective UN surface have been calculated and discussed. For different configurations of oxygen ions at vacancies within the UN(001) slab, the calculated density of states and electronic charge re-distribution was analyzed. Considerable energetic preference of O atom incorporation into the N-v…
Chemisorption of a molecular oxygen on the UN(001) surface: Ab initio calculations
2010
The results of DFT GGA calculations on oxygen molecules adsorbed upon the (0 0 1) surface of uranium mononitride (UN) are presented and discussed. We demonstrate that O2 molecules oriented parallel to the substrate can dissociate either (i) spontaneously when the molecular center lies above the surface hollow site or atop N ion, (ii) with the activation barrier when a molecule sits atop the surface U ion. This explains fast UN oxidation in air.
Ab initio simulation of yttrium oxide nanocluster formation on fcc Fe lattice
2010
Using results of density functional theory (DFT) calculations the first attempt towards the understanding of Y2O3 particles formation in oxide dispersed strengthened (ODS) ferritic–martensitic steels was performed. The present work includes modeling of single defects (O impurity atom, Fe vacancy and Y substitute atom), interaction between substituted Y atoms, Y–Fe vacancy pairs and oxygen impurity atoms in the iron matrix. The calculations have showed the repulsive interaction between the two Y substitute atoms at any separation distances that might mean that the oxygen atoms or O atoms with vacancies are required to form binding between atoms in the yttrium oxide nanoclusters.
Preliminary CAD implementation of EU-DEMO primary heat transfer systems for HCPB breeding blanket option
2019
Abstract This paper focuses on the 3D CAD implementation of the pipework and the main equipment of the Primary Heat Transfer System of EU-DEMO fusion power plant. In particular, the systems related to the Helium-Cooled Pebble Bed Breeding Blanket option are considered here. During the pulse operation, the breeding blanket modules will be the main thermal power source; Divertor and the Vacuum Vessel will contribute in the definition of the total reactor power. All the In-Vessel generated power is rejected to the Power Conversion System through a molten salt Intermediate Heat Transport System. The latter is equipped with an Energy Storage System to allow for continuous operation also during t…
Aufbau und Arbeitsweise eines 12-Kanal- funktionsmeβstandes zur Erfassung und Auswertung schnell ablaufender hämodynamischer Vorgänge
1970
Hemodynamic function studies with radioactive tracers A new set-up, a multichannel function test device, is described for performing hemodynamic function studies with radioactive tracers. After injection of radioactive labelled particles of definite physical and chemical properties, the distribution of radioactivity can be registered simultaneously as function of time at 6 different sites of the body. Each of the 6 detectors used, one of them can be replaced by a fore-arm counter, is equipped with two channels, which can be individually adjusted to the photopeaks of two different radioisotopes. The data are either/not only stored on magnetic tape or/but also fed into a memory unit operating…
On the impact of the heat transfer modelling approach on the prediction of EU-DEMO WCLL breeding blanket thermal performances
2020
Abstract The Water-Cooled Lithium-Lead Breeding Blanket is a key component of a fusion power plant, in charge of ensure Tritium production, shield Vacuum Vessel and magnets and remove the heat power deposited by radiation and particles arising from plasma. The last function is fulfilled by First Wall and Breeding Zone independent cooling systems. Several layouts of BZ coolant system have been investigated in the last years to identify a configuration that might guarantee EUROFER temperature below the limit (550 °C) and good thermal-hydraulic performances (i.e. water outlet temperature of 328 °C). A research activity is conducted to study and compare different modelling approaches to simulat…
Mixed MHD convection and Tritium transport in fusion-relevant configurations
2005
Mixed MHD flow and Tritium transport were computed for a slender poloidal duct, representative of a DEMO HCLL blanket element. 2-D flow and temperature fields were computed in the duct's cross section under the assumption of parallel, fully developed flow, while Tritium concentration C was found by solving a fully 3-D problem with simplifying assumptions at the duct's ends. The spatial distribution of C depended on the intensity and direction of the forced flow. Significant peak factors were obtained if the net flow rate was so low that re-circulation occurred; C maxima were attained near the walls for upward flow, in the core region for downward flow.