Thermal Hydraulics — Single-Channel LOCA

Coupled thermal-hydraulics and fuel behaviour under LOCA conditions.

Simulates a Loss-of-Coolant Accident in a PWR for 600 s, coupling:

  • 1-D axial thermal-hydraulics (2 nodes, two-phase flow with regime selection)

  • 1-D radial fuel/clad heat conduction

  • Cladding thermo-mechanical deformation (elastic + plastic)

  • Cladding failure detection (burst stress criterion)

Port of MATLAB Module 09 (thermalHydraulics.m, initializeFuelRod.m, initializeCoolant.m, funRHS.m, cladFailureEvent.m).

Key restructuring vs. MATLAB: pressures and cladding stress components are computed algebraically at each RHS evaluation (not carried as DAE state variables). The ODE state vector contains only genuinely time-evolving quantities: temperatures, coolant enthalpy, plastic strains.

See also

Thermal Hydraulics — Single-Channel LOCA — Key Facts, LOCA model, wall heat transfer.

class orpheus.thermal_hydraulics.solver.THParams(nz=2, dz0=1.5, fuel_r_in=0.0, fuel_r_out=0.00412, fuel_nr=20, porosity=0.05, burnup=0.0, fgr=0.06, clad_r_in=0.00422, clad_r_out=0.00475, clad_nr=5, roughness=6e-06, p0_ingas=1.2, v_gas_plenum=1e-05, a_flow0=8.914e-05, time_step=1.0, time_end=600.0, T0_table=<factory>, p0_table=<factory>, vel0_table=<factory>, power_table=<factory>, kz=<factory>)[source]

Bases: object

Geometry, boundary conditions and time parameters for the LOCA simulation.

Parameters:
nz: int = 2
dz0: float = 1.5
fuel_r_in: float = 0.0
fuel_r_out: float = 0.00412
fuel_nr: int = 20
porosity: float = 0.05
burnup: float = 0.0
fgr: float = 0.06
clad_r_in: float = 0.00422
clad_r_out: float = 0.00475
clad_nr: int = 5
roughness: float = 6e-06
p0_ingas: float = 1.2
v_gas_plenum: float = 1e-05
a_flow0: float = 8.914e-05
time_step: float = 1.0
time_end: float = 600.0
T0_table: ndarray
p0_table: ndarray
vel0_table: ndarray
power_table: ndarray
kz: ndarray
class orpheus.thermal_hydraulics.solver.THResult(time, fuel_T, clad_T, cool_T, cool_Tsat, cool_TCHF, cool_p, cool_h, cool_vel, cool_void, cool_x, cool_regime, ingas_p, fuel_r, clad_r_in, clad_r_out, clad_sig_r, clad_sig_h, clad_sig_z, clad_sig_I, clad_sig_B, clad_epsPeff, clad_fail_time, params)[source]

Bases: object

Complete time-history of the thermal-hydraulics LOCA calculation.

Parameters:
time: ndarray
fuel_T: ndarray
clad_T: ndarray
cool_T: ndarray
cool_Tsat: ndarray
cool_TCHF: ndarray
cool_p: ndarray
cool_h: ndarray
cool_vel: ndarray
cool_void: ndarray
cool_x: ndarray
cool_regime: ndarray
ingas_p: ndarray
fuel_r: ndarray
clad_r_in: ndarray
clad_r_out: ndarray
clad_sig_r: ndarray
clad_sig_h: ndarray
clad_sig_z: ndarray
clad_sig_I: ndarray
clad_sig_B: ndarray
clad_epsPeff: ndarray
clad_fail_time: float
params: THParams
orpheus.thermal_hydraulics.solver.solve_thermal_hydraulics(params=None)[source]

Run the LOCA thermal-hydraulics simulation.

Parameters:

params (THParams, optional) – Simulation parameters. Uses defaults (PWR LOCA) if not provided.

Return type:

THResult with time histories of all key variables.