Neutronics analysis and thermodynamics studies of several demo breeding blankets for the development of the aina safety code
- Autores: Marco Fabbri
- Directores de la Tesis: Javier Dies Llovera (dir. tes.), Alfredo de Blas del Hoyo (dir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2018
- Idioma: español
- Tribunal Calificador de la Tesis: Guillem Cortes Rossell (presid.), Joaquín Sánchez Sanz (secret.), Neill Peter Taylor (voc.)
- Programa de doctorado: Programa de Doctorado en Ingeniería Nuclear y de las Radiaciones Ionizantes por la Universidad Politécnica de Catalunya
- Materias:
- Texto completo no disponible (Saber más ...)
- Resumen
By 2050 the energy consumption is expected to increase considerably.The production might be mostly based on renewable energy mix driven by the nuclear fusion which could potentially deliver continuous, large-scale power for the long-term without harming the environment. Regrettably, the nuclear fusion still requires numerous developments, which are undergoing around the word, to prove the design feasibility and to evaluate the safety relatad aspects which are to sorne extent embraced this thesis. In light of this, during the last ten years the Nuclear Engineering Research Group (NERG-UPC) has being developing a safety code callad AJNA (acron of Analyses of IN-vessel Accidents) to evaluate the magnetic fusion reactor plasma-wall transients in case of ex-vessel LOCA and overfuelling , determining thermal wall profiles as well as checking the integrity of in-vessel components (melting). Considering the e'v'Olution of technologies and related methodologies, a substantial renewal/improvement plan for AJNA were established. Two specific development tasks are part of this PhD thesis. (i) The definition, standardization and validation of an enhanced methodology to develop new AJNA versions in order to obtain robust models, estimating as accurately as possible the behaviour of the studied systems. (ii) The re-design, generalization and optimization of thermal-hydraulics routines for the determination of the AJNA thermal-wall distributions both in normal and accident scenarios in substitution of the former unverified/unqualified ones. In addition, the thermal hydraulic routines have been validated against commercial software as ANSYS Fluent.
Consequently, the code has been almost rewritten, improved and consolidated giving special attention on document, comment and V&Vaccording to the current software standard requirements . lndeed, severa! novel features have been introduced to extend the modelling capacity of the AJNA application solver and to estimate the errors .
Afterward, two specific AJNA blanket thermal-wall models have been developed: the Water Cooled Pebble Sed JAPANESE DEMO and the Helium Cooled Pebble Bed EUROPEAN-DEMO. According to the established methodology, the complete process of design, improvement and validation has included the complete set of compulsory radiation transport analyses , thermal-hydraulic studies and AJNA thermal-wall model tuning. Furthermore, preliminary assessments of the transient accident scenarios and sensibility studies haw been also performed. So, starting from fully detailed neutronics and thermal hydraulic results, a simplified and conservatiw wall model has been implemented in AJNA obtaining reliable results in a short calculation time validating the approach proposed. lndeed, simplified models haw been iteratiwly built and adjusted, achieving a good agreement with the fully detailed simulation and yielding a maximum absolute temperature differences around 10%. The determination and coherence of the temperature distribution obtained using independenttool s and approaches, ANSYS® Fluent® vs AJNA thermal-hydraulic routines, supports the proposed methodology, hence validating the whole results obtained. Newrtheless, the 1D non-conservatiw temperature field, where present, could be compensated by the application of scaling functions , obtaining a perfect match with the most conservative 30 distribution. In this innovative approach, the scaling functions correspond to the ratios between the most conservatiw radial distribution in the fully detailed and the 10 simulations . Moreowr, thanks to the simplified and endorsed model, sensitivities and screening assessment can be easily perforrned showing how the system reacts as consequences of loads, boundary conditions and perturbations. In light of this, the detailed number of study can be extensively reduced.
To conclude, this multidisciplinary activity has requested the establishment of a specific framework , including skills and tools .
