Total sensitivity and uncertainty analysis for LWR pin-cells with improved UNICORN code

Wan, Chenghui; Cao, Liangzhi; Wu, Hongchun; Shen, Wei

doi:10.1016/j.anucene.2016.09.014

Cited by 11 publications

(2 citation statements)

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“…The COST method has been integrated in our home-developed uncertainty analysis code named UNICORN [7] to provide multivariate samples. In this section, the nuclear-data uncertainties are generally characterized by the multigroup cross-section covariance libraries, which were generated by NJOY [8] based on ENDF/B-VII.1.…”

Section: Numerical Results and Analysismentioning

confidence: 99%

Uncertainty Analysis to C5g7-Td Benchmark Based on the Cost Method

et al. 2021

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A method of Covariance-Oriented Sample Transformation (COST) has been proposed in our previous work to provide the converged uncertainty analysis results with a minimal sample size. The transient calculation of nuclear reactor is a key part of the reactor-physics simulation, so the accuracy and confidence of the neutron kinetics results have attracted much attention. In this paper, the Uncertainty Quantification (UQ) function of the high fidelity neutronics code NECP-X has been developed based on our home-developed uncertainty analysis code UNICORN, building a platform for the UQ of the transient calculation. Furthermore, the well-known space-time heterogeneous neutron kinetics benchmark C5G7 and its uncertainty propagation from the nuclear data to the interested key parameters of the core have been investigated. To address the problem of “the curse of dimensionality” caused by the large number of input parameters, the COST method has been applied to generate multivariate normal-distribution samples in uncertainty analysis. As a result, the law of the assembly/pin normalized power and their uncertainty with respect to time after introducing an instantaneous perturbation has been obtained. From the numerical results, it can be observed that the maximum relative uncertainties for the assembly normalized power can up to be about 1.65% and the value for the pin-wise power distributions can be about 2.71%.

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Section: Numerical Results and Analysismentioning

confidence: 99%

Uncertainty Analysis to C5g7-Td Benchmark Based on the Cost Method

et al. 2021

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“…Bratton, et al, 2014). The first two uncertainty sources can be effectively decreased by using well-established high-fidelity numerical method for neutronics calculation, but the uncertainty of the multi-group cross sections is still significant (M. Pusa, 2012;C. Wan et al, 2017), especially for advanced reactor, e.g., High Temperature Gas-cooled Reactor (D. She et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Generalized Perturbation Theory Based Total Sensitivity and Uncertainty Analysis for High-Fidelity Neutronics Calculation

Hao

Liu

et al. 2021

Front. Energy Res.

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Neutronics calculation for nuclear reactor with high-fidelity technology can significantly reduce the uncertainties propagated from numerical approximation error and model error. However, the uncertainty of input parameters inevitably exists, especially for nuclear data. On the other hand, resonance self-shielding calculation is essential for multi-group assumption based high-fidelity neutronics calculation, which introduce the implicit effect for calculation responses. In order to fully consider the implicit effects in the process of uncertainty quantification, a generalized perturbation theory (GPT) based implicit sensitivity calculation method is proposed in this paper. Combining the explicit sensitivity coefficient, which can be quantified using classic perturbation theory, the total sensitivity coefficient of calculation responses is obtained. Then the total sensitivity and uncertainty module is established in self-developed neutron transport code with high-fidelity technology-HNET. To verify the accuracy of the sensitivity calculation methods proposed in this paper, a two-dimensional fuel pin problem is chosen to verify the sensitivity results, and the numerical results show good agreement with results calculated by a direct perturbation method. Finally, uncertainty analysis for two-dimensional fuel pin problem is performed and some general conclusions are obtained from the numerical results.

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