| 1. |
- Murari, A., et al.
(författare)
-
A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
-
Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Abazov, V. M., et al.
(författare)
-
The upgraded DO detector
- 2006
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 565:2, s. 463-537
-
Tidskriftsartikel (refereegranskat)abstract
- The DO experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid -argon calorimeters and central muon detector, remaining from Run 1, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DO.
|
|
| 6. |
- Dudarev, S. L., et al.
(författare)
-
The EU programme for modelling radiation effects in fusion reactor materials : An overview of recent advances and future goals
- 2009
-
Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 386, s. 1-7
-
Tidskriftsartikel (refereegranskat)abstract
- The EU fusion materials modelling programme was initiated in 2002 with the objective of developing a comprehensive set of computer modelling techniques and approaches, aimed at rationalising the extensive available experimental information on properties of irradiated fusion materials, developing capabilities for predicting the behaviour of materials under conditions not yet accessible to experimental tests, assessing results of tests involving high dose rates, and extrapolating these results to the fusion-relevant conditions. The programme presently gives emphasis to modelling a single class of materials, which are ferritic-martensitic EUROFER-type steels, and focuses on the investigation of key physical phenomena and interpretation of experimental observations. The objective of the programme is the development of computational capabilities for predicting changes in mechanical properties, hardening and embrittlement, as well as changes in the microstructure and phase stability of EUROFER and FeCr model alloys occurring under fusion reactor relevant irradiation conditions.
|
|
| 7. |
- Sublet, J. -Ch., et al.
(författare)
-
Neutron-induced damage simulations : Beyond defect production cross-section, displacement per atom and iron-based metrics
- 2019
-
Ingår i: The European Physical Journal Plus. - : Springer Berlin/Heidelberg. - 2190-5444. ; 134:7
-
Forskningsöversikt (refereegranskat)abstract
- Nuclear interactions can be the source of atomic displacement and post-short-term cascade annealing defects in irradiated structural materials. Such quantities are derived from, or can be correlated to, nuclear kinematic simulations of primary atomic energy distributions spectra and the quantification of the numbers of secondary defects produced per primary as a function of the available recoils, residual and emitted, energies. Recoils kinematics of neutral, residual, charged and multi-particle emissions are now more rigorously treated based on modern, complete and enhanced nuclear data parsed in state of the art processing tools. Defect production metrics are the starting point in this complex problem of correlating and simulating the behaviour of materials under irradiation, as direct measurements are extremely improbable. The multi-scale dimensions (nuclear-atomic-molecular-material) of the simulation process is tackled from the Fermi gradation to provide the atomic- and meso-scale dimensions with better metrics relying upon a deeper understanding and modelling capabilities of the nuclear level. Detailed, segregated primary knock-on-atom metrics are now available as the starting point of further simulation processes of isolated and clustered defects in material lattices. This allows more materials, incident energy ranges and particles, and irradiations conditions to be explored, with sufficient data to adequately cover both standard applications and novel ones, such as advanced-fission, accelerators, nuclear medicine, space and fusion. This paper reviews the theory, describes the latest methodologies and metrics, and provides recommendations for standard and novel approaches.
|
|
| 8. |
- Bakaev, A., et al.
(författare)
-
Interaction of minor alloying elements of high-Cr ferritic steels with lattice defects : An ab initio study
- 2014
-
Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 444:1-3, s. 237-246
-
Tidskriftsartikel (refereegranskat)abstract
- Basic properties of minor alloying elements, namely Mo, W, Nb, Ta, V, Mn, Si entering the conventional and reduced-activation structural Fe-(9-12)Cr steels have been analyzed using ab initio calculations. The electronic structure calculations were applied to study the interaction of minor alloying elements with a number of important and well defined lattice structures, such as point defects, the 1/2 < 111 > screw dislocation core, high angle symmetric grain boundaries and free surfaces. The studied elements were classified according to their similarities and discrepancies regarding the interaction with the above mentioned defects. The refractory alloying elements are found to follow the same trend whereas Mn and Si exhibit peculiar behavior with respect to the interaction with both point and extended lattice defects. The obtained results are discussed and compared with previously published ab initio and available experimental data.
|
|
| 9. |
- Malerba, L., et al.
(författare)
-
Ab initio calculations and interatomic potentials for iron and iron alloys : Achievements within the Perfect Project
- 2010
-
Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 406:1, s. 7-18
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of the FP6 Perfect Project was to develop a first example of integrated multiscale computational models, capable of describing the effects of irradiation in nuclear reactor components, namely vessel and internals. The use of ab initio techniques to study, in the most reliable way currently possible, atomic-level interactions between species and defects, and the transfer of this knowledge to interatomic potentials, of use for large scale dynamic simulations, lie at the core of this effort. The target materials of the Project were bainitic steels (vessel) and austenitic steels (internals), i.e. iron alloys. In this article, the advances made within the Project in the understanding of defect properties in Fe alloys, by means of ab initio calculations, and in the development of interatomic potentials for Fe and Fe alloys are overviewed, thereby providing a reference basis for further progress in the field. Emphasis is put in showing how the produced data have enhanced our level of understanding of microstructural processes occurring under irradiation in model alloys and steels used in existing nuclear power plants.
|
|
| 10. |
- Bakaev, A., et al.
(författare)
-
Effect of isotropic stress on dislocation bias factor in bcc iron : an atomistic study
- 2018
-
Ingår i: Philosophical Magazine. - : Taylor and Francis Ltd.. - 1478-6435 .- 1478-6443. ; 98:1, s. 54-74
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of externally applied stress on the dislocation bias factor (BF) in bcc iron has been studied using a combination of atomistic static calculations and finite element integration. Three kinds of dislocations were considered, namely, a0/2〈1 1 1〉{1 1 0} screw, a0/2〈1 1 1〉{1 1 0} edge and a0〈1 0 0〉{0 0 1} edge dislocations. The computations reveal that the isotropic crystal expansion leads to an increasing or constant dislocation bias, depending on the Burgers vector and type of dislocation. On the other hand, compressive stress reduces the dislocation bias for all the dislocations studied. Variation of the dislocation BF depending on dislocation type and Burgers vector is discussed by analysing the modification of the interaction energy landscape and the capture efficiency values for the vacancy and self-interstitial atom.
|
|
