Causes, course and consequences of fuel damage incident in the Paks NPP, 2003 and connecting thermal-hydraulic analyses

On April 10–11, 2003, an INES-3 classified serious incident caused heavy damage of 30 fuel assemblies in a chemical cleaning instrument installed into a service shaft of Unit 2 in the Paks NPP, Hungary.The preliminaries, the operation of the cleaning tank and the course of the incident are summarized in this paper. Also the post incidental investigations, the preparation for and the process of the recovery work are reviewed. This is the first comprehensive summary of this rather interesting and edificatory event in an international journal paper.The other part of the paper is a summary of the connecting thermal-hydraulic calculations performed at The Institute of Nuclear Techniques, Budapest University of Technology and Economics. An important aim of these sections is demonstrating that CFD was a useful tool for understanding the processes and backing certain decisions from the beginning till the recovery work.