CANDU-6 operation post-simulations using the reactor physics codes DRAGON/DONJON

The operating CANDU-6 reactors are refueled on-power to compensate for the reactivity loss due to fuel burnup. In order to track the core behavior over a long period of operating history without having to use on-site measurement data, a consistent set of nuclear properties must be defined. The 2D as well as 3D capabilities of the DRAGON code are exploited to generate consistent two-group nuclear properties and increments using two different microscopic libraries. These properties are then used in a DONJON core-follow simulation of 220 full power days of operating history at the Gentilly-2 power plant. Comparisons with detectors show that differences tend to decrease with time. This core-follow application was pursued by post-simulations of reactivity mechanism measurements, which are shown to be in good agreement with reactor data. All these simulations demonstrate the DONJON capabilities of fuel management, detector reading evaluation and critical state determination.