Mathematical model for VVER reactor safety assessment calculations in load regulating regimes

28th Symposium of AER on VVER Reactor Physics and Reactor Safety (2018, Olomouc, Czechia)
[5] Reactor dynamics and safety analysis


M.A. Uvakin, I.V. Makhin, E.V. Sotskov (GIDROPRESS)


Work deals with RIA accidents safety assessment problem for VVER reactor, which is operating in load regulating regimes. Model approbation is given by safety assessment for normalized primary power grid frequency regulating regimes (NFR). Frequency regulating regimes leads to turbine load variations and following continuously changing of main reactor facility parameters by feedbacks and regulators actions. Dynamic reactor conditions must be taking into account in safety assessment calculations and needs in specialized methodical approach. Current work gives two solutions. First of them is best estimate approach with full dynamics accounting. Second approach bases on stationary parameters range extension and aims to conservative overlap of possible parameters perturbations by NFR without dynamical initial condition. Dynamical method approbation performs by proposed mathematical model for VVER safety assessment with NFR. Model includes the full scope of calculation and theoretical analysis during NFR transient processes and contains description, algorithm and calculation examples. Safety analysis examples are some RIA type accidents such as control rod ejection, uncontrollable rod group withdrawal and control rod drop.