Hyper-fidelity depletion with discrete motion for pebble bed reactors

Area of Science:

• Nuclear Engineering
• Reactor Physics
• Computational Modeling

Background:

• Previous work established hyper-fidelity (HxF) depletion for stationary pebbles in pebble bed reactors (PBRs).
• Accurate modeling of fuel depletion considering pebble movement is crucial for PBR analysis.
• Traditional methods using spectral zoning provide only average fuel performance data.

Purpose of the Study:

• To couple HxF depletion with a discrete pebble motion scheme for PBRs.
• To demonstrate the capability of HxF with discrete motion in a full-scale reactor model.
• To highlight the unique insights HxF provides into PBR fuel behavior.

Main Methods:

• Implemented a discrete motion scheme within the Serpent 2 code for HxF depletion.
• Developed ad-hoc routines for domain decomposition and pebble recirculation.
• Simulated an approach to equilibrium in a high-temperature gas-cooled reactor model.

Main Results:

• Successfully coupled HxF depletion with discrete pebble motion.
• Demonstrated HxF's capability to model fuel depletion considering pebble movement.
• Generated data showing statistical distributions of fuel parameters for in-core and discarded pebbles.

Conclusions:

• HxF with discrete motion offers a significant advancement in PBR fuel analysis.
• Provides detailed statistical distributions of fuel performance, unlike traditional average-value methods.
• This enhanced understanding can improve the analysis and assessment of PBRs.