Tesis doctoral de Jesús Izquierdo Villena
The acceleration of iter development brings about the need for rapid changes in the design that are not easy to accommodate, either from the safety point of view or from the research perspective. With these complicating factors in mind, this thesis contributes with a computer code for taking into account the plasma wall interaction during in-vessel accidents (aina) and improves the structure and upgrades the contents of the fusion component failure rate database (fcfr db) aina, a safety analysis code taking into account plasma wall interactions, has been developed using as a base the last version of the code called safaly. The key physical models for a realistic plasma wall simulation have been improved in aina, and standard development of the code has been assessed by application of international procedures. The physical models include energy and particle balance, alpha power, ohmic heating, bremsstrahlung and synchrotron losses, confinement modes, disruptions, vertical displacement events, power deposition on the walls, thermohydraulics for blankets and divertor, erosion by physical and chemical sputtering of the plasma facing components, and the fuel recycling from their surfaces, among others. three sets of simulations have been launched. The first set is related to pump malfunction in divertor and first wall cooling loops. The second set is related to loss of plasma control events. The third set considers an overfuelling concurrent with a loss of cooling capacity accident. now, aina is a fully-developed, properly-documented code that allows the evaluation of operational margins of the in-vessel components in front of power fusion trips and other abnormal sequences. Nevertheless, it can be further improved by adding new capabilities such as transport at sol, dust models, heat decay in components, and in- vessel chemical reactions. An example of the interest in improving the code comes, for instance, from the iter contracts with the fusion energy engineering laboratory of the universitat politécnica de catalunya to explore the loss of plasma events and the plasma-passive shutdown by beryllium evaporation (ongoing). the other significant development of this thesis is the update of the fcfr db and the analyses of the tj-ii power supply system from the component failure point of view. On one hand, the fcfr db has been improved by providing a suitable architecture to be used in probabilistic studies. Specifically, the developments that have been completed in the framework of this thesis are: the new quasi-standard, complete, consistent, hierarchical, and flexible component classification or taxonomy; the fusion system breakdown; the synthesized list of failure modes; and the addition of many new records. on the other hand, seven years (1998-2004) of tj-ii power supply systems failure data have been reviewed and processed. It is a short period to perform a reliability analysis for use as a reference for future devices, but it provides an overview of the expected behaviors of the main components in the reliable operation of a power supply system and can be used for making decisions about corrective measures. The process has allowed ranking components by reliability and detecting anomalous reiterated faults beyond the constant failure rate model. In a similar way, the process allowed the identification of repair actions for specific items that have repercussions on the overall availability of the pss. finally, an overview and categorization of tokamak events was conducted. Initiating events (pies) and potential impacts (pis) have been evaluated based on their severities and frequencies, and a ranking scheme was produced by sorting the sequences of aggravating failures in the iter tokamak.
Datos académicos de la tesis doctoral «Iter safety assessment: in-vessel simulation of tokamak events and component reliability approach«
- Título de la tesis: Iter safety assessment: in-vessel simulation of tokamak events and component reliability approach
- Autor: Jesús Izquierdo Villena
- Universidad: Politécnica de catalunya
- Fecha de lectura de la tesis: 10/10/2008
Dirección y tribunal
- Director de la tesis
- Javier Dies Llovera
- Tribunal
- Presidente del tribunal: Carlos Tapia fernández
- José Manuel Perlado martín (vocal)
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- (vocal)