Departure from Nucleate Boiling DNBR Calculator

Nuclear Thermal Hydraulics & Safety: Calculate local Critical Heat Flux ($q^{\prime\prime}_{\text{crit}}$), Departure from Nucleate Boiling Ratio ($\text{DNBR}$), Tong W-3 correlation, and safety limits.

Subchannel Operating Conditions

Coolant Pressure $P$ (MPa):

Coolant Mass Flux $G$ (kg/m²·s):

Local Heat Flux $q^{\prime\prime}_{\text{local}}$ (MW/m²):

Local Steam Quality $x$ (-):

Hydraulic Diameter $D_h$ (mm):

Inlet Subcooling $\Delta h_{\text{sub}}$ (kJ/kg):

Grid Spacer Type (CHF Enhancer):

Critical Heat Flux & Safety Margins

Departure from Nucleate Boiling Ratio

Design Margin vs 1.30: -- %

Critical Heat Flux ($q^{\prime\prime}_{\text{crit}}$)

-- MW/m²

-- BTU/hr·ft²

Boiling Regime & Status

Subcooled Nucleate Boiling

Risk: Clad integrity safe

Overpower Safety Headroom

+-- %

Peak Permissible Flux: -- MW/m²

Regulatory & Engineering Benchmarks:

• Standard NRC / 10 CFR 50.46 DNBR limit: $\text{DNBR} \ge 1.30$ (95/95 confidence)

• Typical PWR peak linear heat generation: $q^{\prime\prime} \approx 1.1 - 1.5$ MW/m²

• Departure from Nucleate Boiling results in sudden vapor blanket insulating cladding, spiking $T_{\text{clad}} > 1000\,^\circ\text{C}$ within seconds.

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Departure from Nucleate Boiling DNBR Calculator

Subchannel Operating Conditions

Critical Heat Flux & Safety Margins

Frequently Asked Questions