Table 3 OpenMC VVER-1000 full-core model: geometry, materials and simulation input.¹⁶.

Reactor / core layout

VVER-1000, full-core hexagonal lattice with 163 fuel assemblies; hex assembly pitch 23.6 cm; active core height 353 cm (planes \(z=\pm 176.5\) cm); geometric core diameter 340 cm; stainless-steel radial reflector thickness 23.6 cm; vacuum radial boundary at \(r=170+23.6=193.6\) cm.

Fuel rods (depletable)

Material au13 (UO\(_2\)): \(\rho =10.4\) g/cm\(^3\), \(T=900\) K; weight fractions U-235 3.87%, U-238 84.60%, O-16 11.53%; annular fuel pellet with \(r_\text {in}=0.075\) cm and \(r_\text {out}=0.3775\) cm; He gap; Zr-Nb-Hf alloy cladding with \(r_\text {in}=0.386\) cm and \(r_\text {out}=0.455\) cm.

Burnable/absorber rods

Material av5 (Al/B/Cr/Fe/Ni/Zr alloy): \(\rho =2.6989\) g/cm\(^3\), \(T=600\) K; B-10 = 0.2 wt%, B-11 = 1.0 wt%; distributed in specified rings; central instrumentation tube present.

Coolant / moderator

Light water: \(\rho =0.727\) g/cm\(^3\), \(T=600\) K; S(\(\alpha ,\beta\)) treatment for H in H\(_2\)O enabled.

Structural / reflector

SS304 reflector (\(\rho =7.90\) g/cm\(^3\), \(T=600\) K); cladding alloy \(\rho =6.452\) g/cm\(^3\), \(T=600\) K.

Pin/assembly statistics

Hex assembly with 330 rods + 1 central tube (asserted in input); intra-assembly pin pitch 1.275 cm.

Monte Carlo settings

Batches = 80, inactive = 20, particles/batch = 250,000; source: uniform box \([-170,-170,-176.5]\) to [170, 170, 176.5], only_fissionable=True.Temperature treatment: multipole=False (WMP disabled), method=’nearest’, tolerance 10 K, range 290–1500 K.

Nuclear data / depletion

ENDF/B-VII.1 HDF5 library; depletion chain chain_endfb71_12_pwr.xml; constant thermal power 3.0 GW\(_\text {th}\); Predictor integrator; time grid: 30 daily steps + 11 monthly steps (\(\approx\)1 year, 41 steps). Fuel volume set from pin geometry and number of assemblies.

Tallies / plots

Tallies disabled for production depletion (blocks commented); assembly and full-core XY/YZ plots exported for QC.