Neutron cross section

In nuclear safety research, the quality of the results of simulation codes is widely determined by the reactor design and safe operation, and the description of neutron transport in the reactor core is a feature of particular importance.

14p christabelhuynh 30-05-2020 42 1   Download

This paper presents a Bayesian approach based on integral experiments to create correlations which do not appear with differential data. Some quantities such as the fission cross section (s), neutron multiplicity (n¯p), neutron spectra (x), etc. are usually neither modeled together nor measured in coincidence, thus there is no correlation matrices in evaluated nuclear data libraries.

8p christabelhuynh 30-05-2020 22 0   Download

These studies are performed in the general framework of transient coupled calculations with accurate neutron kinetics models. This kind of application requires a modeling of the influence on the neutronics of the macroscopic cross-section evolution.

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This article shows how the most recent gadolinium cross sections evaluations appear inadequate to provide accurate criticality calculations for a system with gadolinium fuel pins. In this article, a sensitivity and uncertainty analysis (S/U) has been performed to investigate the effect of gadolinium odd isotopes nuclear cross sections data on the multiplication factor of some LWR fuel assemblies.

11p christabelhuynh 30-05-2020 18 2   Download

A correlated sampling technique has been implemented to estimate the impact of cross section modifications on the neutron transport and in Monte Carlo simulations in one single calculation. This implementation has been coupled to a Total Monte Carlo approach which consists in propagating nuclear data uncertainties with random cross section files.

9p christabelhuynh 29-05-2020 9 2   Download

The deterministic simple least square (LS) approach is employed in the covariance analysis of the total neutron cross section (n,tot) calculated by a microscopic optical potential, CTOM, which is based on a fundamental theory Dirac Brueckner Hartree Fock.

6p christabelhuynh 29-05-2020 4 1   Download

In the current paper, we investigate the application of the Equivalent Generalized Perturbation Theory (EGPT) to derive trends and associated covariances on the neutron capture cross section of one major fission product for both light water reactors and sodium-cooled fast reactors which is Rhodium-103.

9p christabelhuynh 29-05-2020 16 0   Download

Key reactions have been selected to compare JEFF-3.3 (CIELO 2) and IAEA CIELO (CIELO 1) evaluated nuclear data files for neutron induced reactions on 235U and 238U targets. IAEA CIELO evaluation uses reaction models to construct the evaluation prior, but strongly relied on differential data including all reaction cross sections fitted within the IAEA Neutron Standards project.

5p christabelhuynh 29-05-2020 12 0   Download

This paper presents a study of the impact of the nuclear data (cross sections, neutron emission and spectra) on different quantities for spent nuclear fuels (SNF) from Swiss power plants: activities, decay heat, neutron and gamma sources and isotopic vectors.

15p christabelhuynh 29-05-2020 11 1   Download

Instead of running hundreds or thousands of neutronics calculations, we therefore investigate the possibility to take those many cross-section file samples and perform ‘cheap’ sensitivity perturbation calculations. This is efficiently possible with the NEA Nuclear Data Sensitivity Tool (NDaST) and this process we name the half Monte Carlo method (HMM).

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A template for estimating uncertainties (unc.) of measured neutron-induced fission, (n,f), cross-sections (cs) is presented. This preliminary template not only lists all expected unc. sources but also supplies ranges of unc., estimates for correlations between unc. of the same and different experiments which can be used if the information is nonexistent.

9p christabelhuynh 29-05-2020 8 1   Download

Comparisons of calculated and experimental isotopic compositions of used nuclear fuels can provide valuable information on the quality of nuclear data involved in neutronic calculations.

19p christabelhuynh 29-05-2020 11 1   Download