Abstract
The Advanced Multi-Physics (AMP) Nuclear Fuel Performance code (AMPFuel) is focused
on predicting the temperature and strain within a nuclear fuel assembly to evaluate the performance
and safety of existing and advanced nuclear fuel bundles within existing and advanced nuclear
reactors. AMPFuel was extended to include an integrated nuclear fuel assembly capability for
(one-way) coupled radiation transport and nuclear fuel assembly thermo-mechanics. This
capability is the initial step toward incorporating an improved predictive nuclear fuel assembly
modeling capability to accurately account for source-terms, such as neutron flux distribution,
coolant conditions and assembly mechanical stresses, of traditional (single-pin) nuclear fuel
performance simulation.
A novel scheme is introduced for transferring the power distribution from the Scale/Denovo
(Denovo) radiation transport code (structured, Cartesian mesh with smeared materials within each
cell) to AMPFuel (unstructured, hexagonal mesh with a single material within each cell), allowing
the use of a relatively coarse spatial mesh (10 million elements) for the radiation transport and a
fine spatial mesh (3.3 billion elements) for thermo-mechanics with very little loss of accuracy.
With this novel capability, AMPFuel was used to model an entire 1717 pressurized water reactor
fuel assembly with many of the features resolved in three dimensions (for thermo-mechanics and/or
neutronics). A full assembly calculation was executed on Jaguar using 40,000 cores in under 10
hours to model over 160 billion degrees of freedom for 10 loading steps. The single radiation
transport calculation required about 50% of the time required to solve the thermo-mechanics with a
single loading step, which demonstrates that it is feasible to incorporate, in a single code, a
high-fidelity radiation transport capability with a high-fidelity nuclear fuel thermo-mechanics
capability and anticipate acceptable computational requirements.
The results of the full assembly simulation clearly show the axial, radial, and azimuthal variation of
the neutron flux, power, temperature, and deformation of the assembly, highlighting behavior that is
neglected in traditional axisymmetric fuel performance codes that do not account for assembly
features, such as guide tubes and control rods.
