1,720,995 research outputs found
Experimental Activities with the IELLLO Lithium-Lead Facility
No full textFusion power offers the prospect of an almost inexhaustible source of energy for future generations. Although this may be true, it also presents so far serious scientific and engineering challenges. Breeding Blanket is one of key components of future fusion reactors, since it directly involves tritium breeding and energy extraction, both of them critical to development of fusion power. To deal with the development of Breeding Blankets, ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development) designed and built a lead lithium loop (IELLLO: Integrated European Lead Lithium LOop): the experiment aims to support R&D activities for the conceptual and preliminary design of the European test blanket systems. IELLLO was completed, installed and operated at ENEA Brasimone Research Centre. The purpose of this work is to describe the experimental activities that have been carried out concerning the qualification of the facility, and relative instrumentations, for lead lithium application
Magneto-convective effect on tritium transport at breeder unit level for the WCLL breeding blanket of DEMO
Full text linkThe Water-Cooled Lithium-Lead (WCLL) is one of the four breeding blanket concepts proposed by Europe in view of its DEMO reactor. The velocity field of the electrically conducting lead-lithium eutectic alloy inside the blanket is strongly influenced by the external magnetic field used for plasma confinement combined with buoyancy effect. The strength of the magnetohydrodynamics (MHD) effect and of the magneto-convective effect (MHD and buoyancy force) depends on the intensity of the magnetic field and its orientation with respect to the direction of the lead-lithium motion. This phenomenon significantly influences the resulting temperature and velocity fields, and therefore the tritium transport inside the breeding blanket. A multi-physics approach of a 3D tritium transport model is presented for a simplified geometry of the WCLL breeding blanket. In particular, advection-diffusion of tritium into the lead-lithium eutectic alloy, transfer of tritium from the liquid interface towards the steel, diffusion of tritium inside the steel, transfer of tritium from the steel towards the coolant, and advection-diffusion of diatomic tritium into the coolant, temperature field, velocity fields of both lead-lithium and water, buoyancy forces, and MHD effect have been included in this study. The tritium concentrations and the inventories inside the lead-lithium, in the Eurofer pipes and in the baffle, and in the water coolant have been evaluated
Tritium transport in HCLL and WCLL DEMO blankets
No full textThe Helium-Cooled Lithium Lead (HCLL) and Water-Cooled Lithium Lead (WCLL) Breeding Blankets are two of the four blanket designs proposed for DEMO reactor. The study of tritium transport inside the blankets is fundamental to assess their preliminary design and safety features. A mathematical model has been derived, in a new form making makes easier to determine the most critical components as far as tritium losses and tritium inventories are concerned, and to model the tritium performance of the whole system. Two cases have been studied, the former with tritium generation rate constant in time and the latter considering a typical pulsed operation for a time span of 100 h. Tritium inventories and tritium losses are the main output of the model. Tritium concentrations, inventories and losses are initially calculated and compared for the two blankets, in a reference case without permeation barriers or cold traps. A parametric study to show the behavior of the two systems when certain parameters are changed, in order to minimize inventories and/or losses, has been carried ou
Tritium transport model at breeder unit level for WCLL breeding blanket
Full text linkIn a fusion power demonstration plant (DEMO), the development of a tritium transport model is mandatory inorder to correctly predict the tritium concentration inside the liquid metal, the permeatedflux through thestructural materials and into the coolant, playing a fundamental role in guaranteeing tritium self-sufficiency inthe fusion reactor and safety both for the workers and for the external environment. In the present work, a multi-physics 3D tritium transport model has been assessed for a single breeder unit located in the outboard equatorialmodule of the Water-Cooled Lithium Lead (WCLL) breeding blanket of DEMO, adopting an approach that per-mits to have a modelling tool able to be adaptive within certain margins to changes in operating parameters andgeometry. The transport has been modelled considering advection-diffusion of tritium into the lead-lithiumeutectic alloy, transfer of tritium from the liquid interface towards the steel (adsorption/desorption), diffusion oftritium inside the steel, transfer of tritium from the steel towards the coolant (recombination/dissociation),advection-diffusion of diatomic tritium into the coolant. The effect of buoyancy forces, which arise due totemperature variation, has been also considered. Under the above-specified phenomena, tritium concentrations,inventories and losses have been derived
Tritium transport model at breeder unit level for HCLL breeding blanket
Full text linkThe Helium-Cooled Lithium Lead (HCLL) breeding blanket is one of the European blanket designs proposed for
DEMO reactor. A tritium transport model is fundamental for the correct assessment of both design and safety, in
order to guarantee tritium self-su
ffi
ciency and to characterize tritium concentrations, inventories and losses. The
present 2D transport model takes into account a single breeder unit located in the outboard equatorial module of
the HCLL breeding blanket, which is one of the most loaded modules in normal operating conditions. A multi-
physics approach has been adopted considering several physics phenomena, providing for buoyancy e
ff
ect,
temperature
fi
elds, tritium generation rate and velocity pro
fi
le of lead-lithium and coolant. The transport has
been modelled considering advection-di
ff
usion of tritium into the lead-lithium eutectic alloy, transfer of tritium
from the liquid interface towards the steel (adsorption/desorption), di
ff
usion of tritium inside the steel, transfer
of tritium from the steel towards the coolant (recombination/desorption), advection-di
ff
usion of diatomic tri-
tium into the coolant. Tritium concentrations, inventories and losses have been derived under the above spe-
ci
fi
ed phenomena. In particular, the e
ff
ect of buoyancy forces on the tritium transport has been implemented and
compared with the condition without buoyanc
Integration of LiPb loops for WCLL BB of European DEMO
No full textThe eutectic alloy Lithium Lead (LiPb) enriched at 90 % in 6Li is the breeder material for one of the candidate European Breeding Blanket (BB) concepts. Currently under investigation for DEMO reactor, the Water Cooled Lithium-Lead (WCLL), and for the WCLL Test Blanket Module (TBM) that will be qualified in the ITER reactor. The LiPb alloy is used as tritium breeder, neutron multiplier and tritium carrier. The design of the LiPb loops is currently under study and the conceptual design of the main loop components has been completed. For this reason, it becomes mandatory to proceed with the integration of the LiPb loops in the EU DEMO Tokamak building, checking the consistency of the different systems design to be integrated in DEMO reactor building. CAD design and integration of the entire LiPb loops are shown taking into account the building areas assigned, the interfaces with the other systems and the requirement related to the LiPb loop functions. An initial layout of the pipework and the position of the main components have been defined on the basis of the following design requirements: (I) gamma radiation shielding of the components and the pipework; (II) target flow velocity of the LiPb; (III) thermal expansion of the pipes; (IV) possibility to drain the entire loop; (V) redundancy of the loops; (VI) remote maintenance; (VII) position in the building and dimensions of the storage tanks. The 3D model of the entire loops has been provided and integrated in DEMO Tokamak building pointing out the issues related to the interfaces with the other systems and with the building itself
Tritium transport model at the minimal functional unit level for HCLL and WCLL breeding blankets of DEMO
Full text linkDesign Optimization of a Hydrogen Sensor for ITER Pb16Li Blankets
No full textA new design of a hydrogen sensor for Pb-16Li, based on the previous experience and testing results, is performed. The new permeation sensor is made of pure iron. The intention of this optimized design is to improve the response time and to minimize the number of welds to be made. Some simulations were conducted to estimate the time taken for the sensor to reach equilibrium with the partial pressure of hydrogen in the lead-lithium. With respect to the old sensor design, the diameter of the steel connection pipe has been reduced, while its length has been increased. In this way, it was possible to reduce the dead volume within the sensor and increase the permeation area, giving the sensor a faster time response
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
