Nodalization scheme of the VVER-1000 primary circuit: SMASS_T2 – boundary conditions for RCP (1, 2); BLJUN2 – boundary conditions for supplying channels (3, 4); CH2 – channel (5, 6); COL1 – header (7); CH1 – core flow area (8); BVOL_T1 – given boundary cell (9); HSC1 – heat conducting structure (10); BHEAT – boundary condition for fuel rods (11); MOD1 – moderator (12); FUEL1 – fuel (13); CORE1 – pointwise neutron kinetics (14).