Analysis of Factors Influencing the Accuracy of 3-D Flux Synthesis in Nuclear Reactor Primary Shielding

Hou Yunan; Zhang Bin

doi:10.13832/j.jnpe.2025.S1.0166

Volume 46 Issue S1

Jul. 2025

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Hou Yunan, Zhang Bin. Analysis of Factors Influencing the Accuracy of 3-D Flux Synthesis in Nuclear Reactor Primary Shielding[J]. Nuclear Power Engineering, 2025, 46(S1): 166-180. doi: 10.13832/j.jnpe.2025.S1.0166

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Hou Yunan, Zhang Bin. Analysis of Factors Influencing the Accuracy of 3-D Flux Synthesis in Nuclear Reactor Primary Shielding[J]. Nuclear Power Engineering, 2025, 46(S1): 166-180. doi: 10.13832/j.jnpe.2025.S1.0166

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Analysis of Factors Influencing the Accuracy of 3-D Flux Synthesis in Nuclear Reactor Primary Shielding

doi: 10.13832/j.jnpe.2025.S1.0166

Hou Yunan,
Zhang Bin^,

School of Nuclear Science and Engineering, North China Electric Power University, Beijing, 102206, China

Received Date: 2024-10-31
Rev Recd Date: 2025-03-30
Publish Date: 2025-07-09

Abstract

Abstract

The discrete ordinates (S_N) method is one of the primary methods for calculating fast neutron flux in reactor pressure vessels (RPVs). The three-dimensional neutron flux synthesis method based on two-dimensional plus one-dimensional S_N calculations (referred to as the synthesis method) has higher computational efficiency compared with the direct three-dimensional discrete ordinates method (referred to as the three-dimensional calculation method). However, the approximations in the source and geometry processing can affect the accuracy of the synthesis method. In order to analyze the impact of source and geometric approximations on the synthesis method, a benchmark model suitable for the synthesis method was established. The relative error of fast neutron flux calculated by the synthesis method and the three-dimensional calculation of the benchmark model is used as a reference to analyze the influence of source and geometric factors on the synthesis method. In the analysis of source effects, non-uniform radial, axial, and azimuthal power distributions are introduced into the benchmark model to examine the changes in the relative error of fast neutron flux between synthetic calculations and three-dimensional calculations. In the analysis of geometric effects, the core structure of the benchmark model is altered to a square core and a stepped core, respectively, to sequentially analyze the changes in the relative error of fast neutron flux between synthetic and three-dimensional calculations. The results indicate that the maximum relative errors caused by the radial and axial power distributions are both within 1.5%, while the azimuthal power distribution leads to a relative error of 3.5% at the reactor cavity. The square and stepped core structures result in relative errors of 20% and 22%, respectively, in the cavity. In the computations for the typical pressurized water reactor HBR-2, the relative error between the synthesis method and the three-dimensional fast neutron flux calculations at the cavity was 11.65%. These findings demonstrate that the accuracy of the synthesis method for the reactor cavity region still requires improvement.
- Reactor Pressure Vessel (RPV),
- Discrete ordinates (S_N) method,
- 3D flux synthesis,
- Fast neutron flux

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References(18)

References

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