T₀ = 15 °C. VVER-1000: Tk = 313 °C, detailed Thermoptim model (PGV-1000M horizontal SG). VVER-70: Tk = 283 °C, Nuscle model (K-70-29 turbine, saturated steam at 29 bar, separator only). VVER-70 T FWH estimated — uncertainty ±3 pts on FWH %, <0.5 pt on η Xh. Full balance: s4e2.com/exerg/VVER1000_EB.pdf