The task has been accomplished in the framework of Measure 24241 of the Modernization Program of Kozloduy NPP Units 5 and 6.
The services of that project are as follows:
- Development of the methodology;
- Analyses of the boundary conditions for all the IE (Initiating Event) groups listed in the "Design accidents IE list" with influence on the containment construction;
- Analysis of the reliability of the containment structures for ultimate stress estimation:
- Overall performance of the containment in Beyond Design Basis Accident (BDBA) scenarios using simultaneously maximum load of pressure and temperature;
- Individual assessment of the number of the mechanical equipment, located on containment boundary;
- Sensitivity analysis (for operator action sensitivity – to the end-state condition).
For the analysis of the technical condition of the containment the following codes were used: SOLVIA (main calculation), NISA (transient temperature calculation) and FEMAP (universal pre-processor).
The technical condition of components was analyzed with the following codes: ALGOR FEA and PIPE PLUS. The model preprocessor “SUPER DRAW 3D” and ALGOR FEA.