Methodology for Burnup Credit Application for VVER-440 Reactors in Slovakia
16th Symposium of AER on VVER Reactor Physics and Reactor Safety (2006, Bratislava, Slovakia)
Physical Problems of Spent Fuel Decommissioning and Radwaste
Improved calculational methods allow one to take credit for the reactivity reduction associated with fuel burnup. This means reducing the analysis conservativism while maintaining an adequate criticality safety margin. Application of burnup credit requires knowledge of the reactivity state of the irradiated fuel for which burnup credit is taken. The isotopic inventory and reactivity has to by calculated with validated codes.
By depletion calculation is necessary to take into account:
• List of used nuclides
• Cooling time
• Core parameters by irradiation
- Fuel temperature
- Moderator temperature/density
- Soluble boron
- Specific power and operating history
• Axial and horizontal burnup profiles
In this paper is numerical evaluation of impact of above parameters on reactivity for VVER-440 fuel (enrichment 3.6%) in condition of wet storage presented. The bounding conditions are defined. The SCALE 5.0 system is used for depletion and criticality calculation.