Statistical analysis of fuel failures in large break loss-of-coolant accident (LBLOCA) in EPR type nuclear power plant

• Published in: Nuclear engineering and design 2015-04, Vol.285, p.1-14
• Main Authors: Arkoma, Asko, Hänninen, Markku, Rantamäki, Karin, Kurki, Joona, Hämäläinen, Anitta
• Format: Article
• Language: English
• Subjects: Accidents; Fluid flow; Fuels; Hydraulics; Nuclear power generation; Nuclear power plants; Rods; Simulation
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/j.nucengdes.2014.12.023

•The number of failing fuel rods in a LB-LOCA in an EPR is evaluated.•59 scenarios are simulated with the system code APROS.•1000 rods per scenario are simulated with the fuel performance code FRAPTRAN-GENFLO.•All the rods in the reactor are simulated in the worst scenario.•Results suggest that the regulations set by the Finnish safety authority are met. In this paper, the number of failing fuel rods in a large break loss-of-coolant accident (LB-LOCA) in EPR-type nuclear power plant is evaluated using statistical methods. For this purpose, a statistical fuel failure analysis procedure has been developed. The developed method utilizes the results of nonparametric statistics, the Wilks’ formula in particular, and is based on the selection and variation of parameters that are important in accident conditions. The accident scenario is simulated with the coupled fuel performance – thermal hydraulics code FRAPTRAN-GENFLO using various parameter values and thermal hydraulic and power history boundary conditions between the simulations. The number of global scenarios is 59 (given by the Wilks’ formula), and 1000 rods are simulated in each scenario. The boundary conditions are obtained from a new statistical version of the system code APROS. As a result, in the worst global scenario, 1.2% of the simulated rods failed, and it can be concluded that the Finnish safety regulations are hereby met (max. 10% of the rods allowed to fail).