Analysis of a rod withdrawal in a PWR core with the neutronic-thermalhydraulic coupled code RELAP/PARCS

摘要

With the implementation of advanced fuel management, margins to safety and licensing limits are frequently reduced. This leads to general development of advanced methods that reduce the level of conservation by implementing kinetics methods that capture spatial effects occurring during reactor transients more accurately. The behavior of a Trillo NPP core configuration in a REA (Rod Ejection Accident) for different nominal power conditions at BOC and at EOC have been analyzed using the coupled neutronic-thermal-hydraulic code RELAP5/PARCS2.7. The Reactor Ejection Accident (REA) belongs to the Reactivity Initiated Accidents (R1A) category of accidents, and it is part of the licensing basis accident analyses required for pressure water reactors (PWR). The REA consists of a rod ejection due to the failure of its drive mechanism. The evolution is driven by a continuous reactivity insertion. The main factor limiting the consequences of the accident is the Doppler Effect. These analyses allow knowing more accurately the PWR real plant phenomenology in the RIA most limiting conditions, in this way the conclusions will be realistic.