Fuel Behavior Calculations for Developed Fuel and Cycle at Paks NPP, Hungary
26th Symposium of AER on VVER Reactor Physics and Reactor Safety (2016, Helsinki, Finland)
Fuel behavior in normal conditions
Abstract
FUEL BEHAVIOR CALCULATIONS FOR DEVELOPED FUEL AND CYCLE AT PAKS NPP, HUNGARYGábor BÓNA, Imre NEMES, Botond BELICZAI Paks NPP, Hungary bonag@npp.huABSTRACTFrom 2015 15 months cycles are being introduced at Paks NPP. For this, the 4.7% enrichment fuel assembly (with 6 Gd pins) is used. For these long cycles the economic solutions can only be improved by increasing the water – Uranium ratio. New fuel geometry is proposed with some modifications such as smaller clad thickness and outer clad diameter, the lack of the central hole and higher average enrichment. For the new assemblies the loading patters are determined and the required neutronic and thermo-hydraulic calculations were made. In my presentation I would like to show the results of the fuel behavior calculations, which were carried out for this new fuel type. We found that the main points are the identification of the pins with the highest parameters (fuel temperatures, dimension changes, fission gas release and hoop stress) and the question of the start-up speed. We developed a tool, which allows us to calculate the fuel behavior parameters for all assemblies and all pins in the core. The results are very interesting. The identification of the most “loaded” pins caused some surprises, which justifies the need for the full core fuel behavior calculations. 26th Symposium of AER on VVER Reactor Physics and Reactor Safety 51 10 – 14 October 2016, Helsinki, Finland