Operational improvements of nuclear power plants in Belgium by optimized tuned control

Belgium has installed seven nuclear power plants. They are all of the PWR type, five of them are of the 900 to 1000 MWe, three loop plants, the two others are 400 MWe, two loop plants. The introduction of these units in the power system is not evident and required an evaluation of the capability the unit to cope with the power system requirements. This evaluation led to many improvements in the design of the control systems as well on protection and the BOP systems. These improvements were not all implemented during the design phase, since some problems were discovered during operation. This paper will describe the problems that were identified and their solutions as they were implemented in Belgium. Most of the identified problems were discovered at the start-up period during which many transient tests were performed. As this is a quite exceptional period in the life of the plant, it was decided to built a digital data acquisition system, collecting about 240 critical parameters in the power plant at a fast rate. For each NPP a collection of about 200 transients were recorded and kept for further analysis and review. This data bank was also very valuable for code validation. The data acquisition system and the data bank will also be described in this paper