Blanket Thermal-Hydraulics Codes
Thermal-hydraulics codes model heat removal and coolant flow in the blanket, turning neutron heating into temperatures and stresses.
Removing the heat
The blanket surrounding a fusion plasma absorbs neutron and radiation power and must transfer it to a coolant without overheating. Blanket thermal-hydraulics codes take the volumetric heating from neutron transport and solve the coupled fluid-flow and heat-conduction problem, predicting material temperatures, coolant behavior, and the thermal stresses the structure must endure.
This is where nuclear physics meets mechanical engineering: the neutronics sets the heat source, and the thermal-hydraulics determines whether the design survives it.
Computational fluid dynamics
Coolant flow is modeled with computational fluid dynamics, solving the Navier-Stokes equations for the coolant coupled to conduction in the solid. For liquid-metal breeders, magnetohydrodynamic effects, the interaction of the flowing conductor with the magnetic field, alter the flow and pressure drop and must be included, a specialized extension of ordinary CFD.
Coupling to neutronics and structures
The workflow couples three domains: neutronics for the heat source, thermal-hydraulics for the temperature field, and structural mechanics for the resulting stresses and deformation. Multiphysics coupling among them, an instance of HPC coupling, yields a self-consistent picture of blanket behavior under load.
Design relevance
For the Hyperion breeder, whose blanket must both breed tritium at a ratio of 1.8 and remove the neutron heating from 88.7 MW of fusion power, thermal-hydraulic simulation checks that coolant channels keep materials within their limits. All results are simulation studies preceding construction, with performance confirmable only in operation.
- Turns neutron heating into temperatures and stress
- CFD for coolant plus conduction in solids
- Liquid-metal flow needs MHD effects
- Coupled with neutronics and structural mechanics