Determination of neutron flux redistribution factors for a typical pressurized water reactor ex-core measurements using Monte Carlo technique
ID Goričanec, Tanja (Author), ID Kos, Bor (Author), ID Ambrožič, Klemen (Author), ID Trkov, Andrej (Author), ID Snoj, Luka (Author), ID Kromar, Marjan (Author)

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In a typical pressurized water reactor, neutron detectors located outside the reactor core monitor reactor power. In addition, they are also used to measure the reactivity of the control rods. A novel approach to calculate the ex-core neutron detector response in a typical pressurized water reactor using the Monte Carlo technique is presented. A detailed ex-core model of the Krško nuclear power plant was developed using the Monte Carlo neutron transport code MCNP. Due to the location of the ex-core neutron detectors, the hybrid code ADVANTG is used to generate variance reduction parameters to accelerate the convergence of the results outside the reactor core. To use ADVANTG, the fixed neutron source had to be reconstructed from the criticality core calculation. This paper presents the sensitivity analysis of the response of the ex-core detectors to the neutron data libraries used, the description of the fixed neutron source and the ADVANTG parameters. It was found that a pin-wise description of the neutron source for at least two rows of fuel assemblies at the core periphery is necessary for accurate results. Our results show the importance of a correct description of the prompt neutron spectra in the high energy region and the impact this has on the response of the ex-core detectors. The method in which the prompt neutron fission spectra for important fission nuclides are weighted by the calculated reaction rates has been shown to be the best approximation, with deviations from the reference calculation within statistical uncertainty. The effect of nuclear data libraries on the response of the ex-core detector was investigated, and the difference between the ENDF/B-VII.0 and the ENDF/B-VIII.0 nuclear data libraries was ∼11%. When the deficient evaluation of the $^{56}$Fe isotope included in the ENDF/B-VIII.0 nuclear data library was replaced by the improved evaluation from the IAEA INDEN project, the differences decreased to ∼3.7%. In addition, neutron flux redistributions due to control rod movement were investigated and flux redistribution factors were updated using Monte Carlo particle transport methods. The reaction rate redistribution factors obtained with methods presented in this paper are within 1% agreement with the currently used factors.

Keywords:MCNP, ADVANTG, pressurized water reactor, Monte Carlo neutron transport, control rod, neutron flux redistribution factor, rod insertion, Krško nuclear power plant
Work type:Article
Typology:1.01 - Original Scientific Article
Organization:FMF - Faculty of Mathematics and Physics
Publication status:Published
Publication version:Version of Record
Number of pages:20 str.
Numbering:Vol. 11, art. 1137867
PID:20.500.12556/RUL-155256 This link opens in a new window
ISSN on article:2296-598X
DOI:10.3389/fenrg.2023.1137867 This link opens in a new window
COBISS.SI-ID:142840067 This link opens in a new window
Publication date in RUL:22.03.2024
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Record is a part of a journal

Title:Frontiers in energy research
Shortened title:Front. energy res.
Publisher:Frontiers Media
COBISS.SI-ID:27719207 This link opens in a new window


License:CC BY 4.0, Creative Commons Attribution 4.0 International
Description:This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

Keywords:jedrska fizika, jedrski reaktor


Funder:ARRS - Slovenian Research Agency
Project number:L2-8163
Name:Razvoj metod za izračun nevtronskega polja v zadrževalnem hramu tlačnovodne jedrske elektrarne

Funder:ARRS - Slovenian Research Agency
Project number:L2-2612
Name:Stabilnost jedrskih reaktorjev pri obratovanju v načinu sledenja bremenu

Funder:ARRS - Slovenian Research Agency
Project number:P2-0073
Name:Reaktorska fizika

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