scholarly journals Total Monte Carlo acceleration for the PETALE experimental programme in the CROCUS reactor

2019 ◽  
Vol 211 ◽  
pp. 03002 ◽  
Author(s):  
Axel Laureau ◽  
Vincent Lamirand ◽  
Dimitri Rochman ◽  
Andreas Pautz
Keyword(s):  
Monte Carlo ◽  
Cross Section ◽  
Reaction Rate ◽  
Brute Force ◽  
Experimental Programme ◽  
Bayesian Monte Carlo ◽  
Correlated Sampling ◽  
The Cross

The Bayesian Monte Carlo technics requires individual evaluations of random cross section files based on a Total Monte Carlo propagation. This article discusses the use of a Correlated Sampling acceleration applied to TMC calculations for experiments where a brute force technics is too expensive. An e_cient estimation of the reaction rate uncertainties in small dosimeters is obtained, together with the inter-dosimeter correlation associated to the cross section uncertainties.

scholarly journals Bayesian Monte Carlo assimilation for the PETALE experimental programme using inter-dosimeter correlation

2020 ◽  
Vol 239 ◽  
pp. 18004
Author(s):  
Axel Laureau ◽  
Vincent Lamirand ◽  
Dimitri Rochman ◽  
Andreas Pautz
Keyword(s):  
Monte Carlo ◽  
Reaction Rate ◽  
Nuclear Data ◽  
Experimental Results ◽  
The Other ◽  
Nuisance Parameters ◽  
Strong Constraint ◽  
Experimental Programme ◽  
Bayesian Monte Carlo ◽  
Assimilation Process

This article presents the methodology developed to generate and use dosimeter covariances and to estimate nuisance parameters for the PETALE experimental programme. In anticipation of the final experimental results, this work investigates the consideration of these experimental correlations in the Bayesian assimilation process on nuclear data. Results show that the assimilation of a given set of dosimeters provides a strong constraint on some of the posterior reaction rate predictions of the other dosimeters. It confirms that, regarding the assimilation process, the different sets of dosimeters are correlated.

scholarly journals Correlated energy uncertainties in reaction rate calculations

2020 ◽  
Vol 642 ◽  
pp. A41
Author(s):  
Richard Longland ◽  
Nicolas de Séréville
Keyword(s):  
Monte Carlo ◽  
Cross Section ◽  
Reaction Cross Section ◽  
Reaction Rate ◽  
Resonance Energy ◽  
Reaction Rates ◽  
Reaction Cross ◽  
Current Interest ◽  
Resonance Energies ◽  
The Impact

Context. Monte Carlo methods can be used to evaluate the uncertainty of a reaction rate that arises from many uncertain nuclear inputs. However, until now no attempt has been made to find the effect of correlated energy uncertainties in input resonance parameters. Aims. Our goal is to investigate the impact of correlated resonance energy uncertainties on reaction rates. Methods. Using a combination of numerical and Monte Carlo variation of resonance energies, the effect of correlations are investigated. Five reactions are considered: two fictional, illustrative cases and three reactions whose rates are of current interest. Results. The effect of correlations in resonance energies depends on the specific reaction cross section and temperatures considered. When several resonances contribute equally to a reaction rate, and when they are located on either side of the Gamow peak, correlations between their energies dilute their effect on reaction rate uncertainties. If they are both located above or below the maximum of the Gamow peak, however, correlations between their resonance energies can increase the reaction rate uncertainties. This effect can be hard to predict for complex reactions with wide and narrow resonances contributing to the reaction rate.

scholarly journals Uncertainty propagation based on correlated sampling technique for nuclear data applications

2020 ◽  
Vol 6 ◽  
pp. 8 ◽  
Author(s):  
Axel Laureau ◽  
Vincent Lamirand ◽  
Dimitri Rochman ◽  
Andreas Pautz
Keyword(s):  
Monte Carlo ◽  
Cross Section ◽  
Neutron Transport ◽  
Uncertainty Propagation ◽  
Computation Time ◽  
Sampling Technique ◽  
Nuclear Data ◽  
Correlated Sampling ◽  
Enriched Uranium ◽  
The Impact

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. The TMC-CS (Total Monte Carlo with Correlated Sampling) approach offers an interesting speed-up of the associated computation time. This methodology is detailed in this paper, together with two application cases to validate and illustrate the gain provided by this technique: the highly enriched uranium/iron metal core reflected by a stainless-steel reflector HMI-001 benchmark, and the PETALE experimental programme in the CROCUS zero-power light water reactor.

scholarly journals Monte Carlo MCNP modeling of a HPGe detector and its efficiency for extended sample geometry

2012 ◽  
Vol 20 ◽  
pp. 134
Author(s):  
A. Kalamara ◽  
M. Diakaki ◽  
R. Vlastou ◽  
M. Kokkoris ◽  
F. Androulakaki ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Cross Section ◽  
Neutron Beam ◽  
Hpge Detector ◽  
Experimental Setup ◽  
Sample Geometry ◽  
The Cross ◽  
Detector Model

The activity of an extended 241Am sample with complex shielding and geometry has been measured by an 80% HPGe detector, after its irradiation by a neutron beam at 10.4 MeV, in order to determine the cross section of the reaction 241Am(n,2n)240Am. Due to the complexity of sample’s geometry, the estimation of the detector’s efficiency has been achieved by MCNP5 Monte Carlo simulations. The simulations have been gradually evolved in order to define the detector model, the experimental setup geometry (geometry definition), the sample’s density and finally the detector’s efficiency for the irradiated 241Am sample.

scholarly journals IMPROVEMENT OF SCALE-XSProc MULTIGROUP CROSS SECTION PROCESSING BASED ON THE CENTRM POINTWISE SLOWING DOWN CALCULATION

2021 ◽  
Vol 247 ◽  
pp. 02011
Author(s):  
Seog Kim Kang ◽  
Andrew M. Holcomb ◽  
Friederike Bostelmann ◽  
Dorothea Wiarda ◽  
William Wieselquist
Keyword(s):  
Monte Carlo ◽  
Cross Section ◽  
Cross Sections ◽  
Reaction Rate ◽  
Neutron Transport ◽  
Energy Structure ◽  
Reactor Physics ◽  
Slowing Down ◽  
Monte Carlo Calculations ◽  
Scattering Matrices

The SCALE-XSProc multigroup (MG) cross section processing procedure based on the CENTRM pointwise slowing down calculation is the primary procedure to process problem-dependent self-shielded MG cross sections and scattering matrices for neutron transport calculations. This procedure supports various cell-based geometries including slab, 1-D cylindrical, 1-D spherical and 2-D rectangular configurations and doubly heterogeneous particulate fuels. Recently, this procedure has been significantly improved to be applied to any advanced reactor analysis covering thermal and fast reactor systems, and to be comparable to continuous energy (CE) Monte Carlo calculations. Some reactivity bias and reaction rate differences have been observed compared with CE Monte Carlo calculations, and several areas for improvement have been identified in the SCALE-XSProc MG cross section processing: (1) resonance self-shielding calculations within the unresolved resonance range, (2) 10 eV thermal cut-off energy for the free gas model, (3) on-the-fly adjustments to the thermal scattering matrix, (4) normalization of the pointwise neutron flux, and (5) fine MG energy structure. This procedure ensures very accurate MG cross section processing for high-fidelity deterministic reactor physics analysis for various advanced reactor systems.

Total Cross Section of 16O(p,α)13N from Threshold to 7.7 MeV

1973 ◽  
Vol 51 (16) ◽  
pp. 1689-1692 ◽  
Author(s):  
R. H. McCamis ◽  
G. A. Moss ◽  
J. M. Cameron
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Stellar Evolution ◽  
Reaction Rate ◽  
Previous Estimate ◽  
Activation Procedure ◽  
The Cross

The reaction 16O(p,α)13N plays an important part in explosive oxygen burning in stars, and the magnitude of its cross section is important in various astrophysical models of stellar evolution. Therefore, the cross section for this reaction was measured from threshold to 7.7 MeV, which includes the range of astrophysical importance. The experiment was performed using an activation procedure, which is described. At the highest energies obtained, the cross section was compared to, and agrees very well with, earlier measurements. The reaction rate for this reaction was calculated, and was found to be much lower than the previous estimate for it.

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