Statistical analysis of plant data for revision of operating rules minimizing risk of PCI failure in BWRs
Ladda ner
Typ
Examensarbete för masterexamen
Master Thesis
Master Thesis
Program
Nuclear engineering, MSc
Publicerad
2013
Författare
Azadrad, Alborz
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Nuclear power reactors are responsible for producing electricity; the electricity comes from a generator, driven by turbines that receive their power from expanding steam forcing its way through the turbine blades. The steam in turn comes from a cylindrically shaped vessel that houses thousands of rods containing a uranium compound that through a process called nuclear fission generate heat which in turn boils the water. Power is controlled by control rods that slide between the rod bundles, an insertion result in a power decrease and vice versa. During power increases there is a risk the fuel rods crack and release radioactive material in the steam cycle. Fuel related failures that lead to such events are called PCI (pellet-cladding interaction) failure. Data from past operation experience, both from commercial operation and from power ramp tests, have been collected and analyzed, in order to evaluate the probability of PCI failures. The parameters that have been analyzed are the maximum power level (LHGR) and power steps for each pin node during a cycle or during a power ramp test. This information has then been graphically presented together with some operating restrictions (the TMOL curve and the current PCI threshold curve). Based on this information, a statistical analysis has been performed assessing the PCI failure probability as function of the power step. The derived probabilities are highly determined by the results from the power ramp tests. It should be noted that the PCI failure probability is estimated not only to be dependent on the magnitude of the power step, but also on the burnup level and the starting power level at which the power step has been taken, as well as the possible occurrence of pellet and cladding defects. These dependencies, not evaluated in this study, are recommended to be treated in future analyses.
Beskrivning
Ämne/nyckelord
Energi , Beräkningsfysik , Teknisk fysik , Energy , Computational physics , Engineering physics