Shut-down margin study for the next generation VVER-1000 reactor including 13 × 13 hexagonal annular assemblies

Shut-Down Margin (SDM) for the next generation annular fuel core of typical VVER-1000, 13 × 13 assemblies are calculated as the main aim of the present research. We have applied the MCNP-5 code for many cases with different values of core burn up at various core temperatures, and therefore their corresponding coolant densities and boric acid concentrations. There is a substantial drop in SDM in the case of annular fuel for the same power level. Specifically, SDM for our proposed VVER-1000 annular pins is calculated when the average fuel burn up values at the BOC, MOC, and EOC are 0.531, 11.5, and 43 MW-days/kg-U, respectively.

► Shut-Down Margin (SDM) for the next generation annular fuel core of typical VVER-1000, 13 × 13 assemblies are calculated. ► The MCNP-5 code is run for many cases with different core burn up at various core temperatures. ► There is a substantial drop in SDM in the case of annular fuel for the same power level. ► SDM for our proposed VVER-1000 annular pins is calculated for specific average fuel burn up values at the BOC, MOC, and EOC.