Technology on the on-the-fly generation of continuous thermal neutron scattering cross section in MCNP for microreactor multi-physics coupling

Wang Lipeng; Zou Jingjie; Zhao Ruoxiu; Cao Lu; Jiang Duoyu; Hu Tianliang; Liu Shichang

doi:10.11884/HPLPB202537.250254

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Wang Lipeng, Zou Jingjie, Zhao Ruoxiu, et al. Technology on the on-the-fly generation of continuous thermal neutron scattering cross section in MCNP for microreactor multi-physics coupling[J]. High Power Laser and Particle Beams. doi: 10.11884/HPLPB202537.250254

Citation:

Wang Lipeng, Zou Jingjie, Zhao Ruoxiu, et al. Technology on the on-the-fly generation of continuous thermal neutron scattering cross section in MCNP for microreactor multi-physics coupling[J]. High Power Laser and Particle Beams. doi: 10.11884/HPLPB202537.250254

Citation:

Wang Lipeng, Zou Jingjie, Zhao Ruoxiu, et al. Technology on the on-the-fly generation of continuous thermal neutron scattering cross section in MCNP for microreactor multi-physics coupling[J]. High Power Laser and Particle Beams. doi: 10.11884/HPLPB202537.250254

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Technology on the on-the-fly generation of continuous thermal neutron scattering cross section in MCNP for microreactor multi-physics coupling

doi: 10.11884/HPLPB202537.250254

1.
Northwest Institute of Nuclear Technology, Xi’an 710024, China
2.
School of Nuclear Science and Technology, ‌Shanghai Jiao Tong University‌, Shanghai 200240, China
3.
School of Nuclear Science and Engineering, North China Electric Power University, Beijing 102206, China

Received Date: 2025-08-09
Accepted Date: 2025-09-02
Rev Recd Date: 2025-09-02

Available Online: 2025-09-12

Abstract

Abstract

Background
Microreactors exhibit closely coupled neutronic-thermal-mechanical responses during operation, accompanied by highly non-uniform temperature distributions. Traditional on-the-fly cross-section generation methods, such as Doppler broadening in MCNP, are limited to the resolved resonance region and cannot handle temperature-dependent thermal neutron scattering laws (TSL), which are critical for thermal-spectrum systems.
Purpose
To address this gap, this study aims to develop an on-the-fly TSL cross-section generation capability within MCNP based on statistical sampling, with a focus on thermal neutron scattering in high-temperature moderators such as ZrHₓ, and to enable high-fidelity neutronic-thermal coupling analysis in microreactor simulations.
Methods
A statistical sampling approach was implemented for on-the-fly computation of thermal scattering cross-sections. Multi-temperature cross-section evaluations were carried out for hydrogen in ZrHₓ, comparing discrete and continuous TSL treatments. The method was macroscopically validated through k_eff calculations in TRIGA and TOPAZ reactors. Furthermore, integrated neutronic-thermal coupling simulations were performed using unstructured-mesh MCNP coupled with ABAQUS.
Results
The developed on-the-fly cross-section method produces k_eff values in good agreement with those obtained using pre-generated offline libraries. The integration with unstructured particle transport in MCNP allows spatially precise accounting of temperature feedback in the moderator region.
Conclusions
The new on-the-fly TSL capability enhances the accuracy of temperature-dependent neutronics modeling in thermal-spectrum microreactors. Coupled with unstructured meshing, it provides an essential foundation for high-fidelity multi-physics simulations of solid-state compact microreactors.
- MCNP,
- continuous thermal neutron scattering cross-section,
- on-the-fly generation,
- unstructured mesh Monte Carlo,
- multi-physics,
- effective multiplication factor

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References(12)

References

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