Contribution to the validation of best estimate plus uncertainties coupled codes for the analysis of NK-TH nuclear transients
- Autores: Raimon Pericas Casals
- Directores de la Tesis: Lluís Batet (dir. tes.), Francesc-Josep Reventós Puigjaner (dir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2015
- Idioma: inglés
- Tribunal Calificador de la Tesis: Kostadin Ivanov (presid.), Mª del Carmen Pretel Sánchez (secret.), Rafael Miró Herrero (voc.)
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
The calculations that allow the operating license of the nuclear reactors are usually made using conservative methods. This conservatism, often excessive, limits the actual capabilities of the industry to increase energy production from nuclear power plants. Currently the best estimate calculations are the most advanced tool in the study and analysis of hypothetical accident scenarios. This new technique is superior compared to the old methodology, where the safety margins were established by experts, using assumptions operation and conservative assumptions. The methodology of the best estimate plus uncertainties calculations is able to provide a solution in terms of increased production of nuclear energy without compromising the safety margins. This thesis presents a comparison between the methodology of the best estimate plus uncertainties and methodology within the traditional conservative calculations of coupled three-dimensional neutron-kinetic and thermo-hydraulic. In the framework of the security analysis using system code, coupled three-dimensional kinetic thermo-hydraulic calculations are also the most advanced tools, and they are particularly suitable for those transients involving basic asymmetric conditions and return to criticality scenarios. The best estimate plus uncertainties calculation methodology has been applied with success for the first time within the framework of the present study. This group of new methods requires a new set of calculation tools as well as defining criteria for their validation. The thesis analyzes the existing tools and includes the improvement of some of them in order to allow a more accurate and reliable usage. The scenarios of interest are those that require the coupling between three-dimensional neutron kinetics codes and thermo-hydraulics codes. The first improvement made is based on a methodology for creating a cross section library which applies to any point in the life cycle of the reactor studied. Second improvement applies by establishing an interface between the equations of motion and control rods of neutron absorbing. The analysis of the main steam line break scenario in a pressurized water reactor nuclear power plant, included in this thesis, allows exercising the generated logics and applying it to the cases that are coming for the future innovative license calculations.
