Development and parameter study of the containment analysis program EBBE

Abstract

To be able to study the temperature in the wetwell for different types of pipe ruptures in order to be able to draw power limitation diagrams to determine the highest allowed thermal power during operation with non-zero power, a new model of the containment simulation program Ebbe has been developed. Ebbe is a containment simulation program focusing on simulating the temperature in the liquid part of the wetwell. Ebbe has then been compared to other simulation program results such as the old Ebbe code from 1989, and other containment simulating programs to verify that the results are reasonable. This has been done as a master thesis for OKG, to improve the code used in Ebbe that could only before handle guillotine breaks, because guillotine breaks was seen as theworst case scenario. To enable Ebbe to also simulate minor ruptures Ebbe has been rewritten from its very core, where the most important new implementations are a reactor vessel with pressure calculations. The new version of Ebbe has also switch programming language from Fortran 77 used in old Ebbe to Matlab to simplify future maintenance of the code. The old Ebbe code has also been revised in order to locate approximations and assumptions, those approximations and assumptions have been studied if possible by study the end results when the approximation or assumption is removed. The objective for the master thesis was to show that the new Ebbe had results in proximity to other containment simulating programs including old Ebbe, and also had acceptable behaviours of certain parameters such as the pressure. Future development of the new Ebbe code is required to include logic from more cases and also the different plants.