The task has been accomplished in the framework of Measure 26281 of the Modernization Program of Kozloduy NPP Units 5 and 6.
The services provided under that project are, as follows:
- Development of the methodology;
- Analyses of the boundary conditions for all the Initiating Events (IE) groups listed in the "Design accidents IE list";
- Development (actualization) of Relap5 Mod 3.3 model;
- Validation and Verification of the model (Engineering hand book & data base book);
- Thermo-hydraulic analysis (using groups Symptom-Based Emergency Operating Procedures (SBEOP) operator actions);
- Sensitivity analysis (for operator action sensitivity – to the end-state condition);
- Development of a detailed model for SG (Steam Generator) critical component dynamic analysis (all boundary elements between primary and secondary circuit). Structural Analysis of the SG performance by using the Finite Element Method;
- Estimation of the SG components damage state, ultimate stress assessment and stress capacity (the pressure and temperature influence);
- Estimation of the conditional probability of failure of the SG critical components;
- Reliability assessment of critical components and estimation of probability of “Primary to secondary LOCA accidents” occurrence;
- Quantitative Analysis of Radioactive Releases in case of Initiating Event "Primary to secondary Loss of Coolant Accident (LOCA) – SG collector lifting - Dn 43";
- Technical proposals for safety enhancement.