Neutron Cross Section Evaluations of Fission Products Below the Fast Energy Region

Chang, Jonghwa; Mughabghab, S.F.

doi:10.2172/759039

Cited by 28 publications

(21 citation statements)

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“…• The Atlas file is then converted into an ENDF-6 format with the aid of the computer program PTANAL [7]. In this procedure, average s-and p-wave radiative widths are supplied when such data is missing, and spin assignments of resonances of undetermined values are randomly made with the condition that the (2J+1) law for level density is followed.…”

Section: Methodsmentioning

confidence: 99%

Neutron Cross Section Uncertainties in the Thermal and Resonance Regions

Mughabghab

Obložinský

2008

Nuclear Data Sheets

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In the Atlas of Neutron Resonances, special care was expended to ensure that the resonance parameter information reproduces the various measured thermal cross sections, as well as the infinite dilute resonance integrals for Z = 1-100. In contrast, the uncertainties of the recommended quantities do not match those generated from the uncertainties of the resonance parameters. To address this problem, the present study was initiated to achieve consistency for 15 actinides and 21 structural and coolant moderator materials. This is realized by assigning uncertainties to the parameters of the negative-energy resonances and changing, if necessary, significantly the uncertainties of the low-lying positive-energy resonances. The influence of correlations between parameters on the derived uncertainties is examined and discussed.

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Section: Methodsmentioning

confidence: 99%

Neutron Cross Section Uncertainties in the Thermal and Resonance Regions

Mughabghab

Obložinský

2008

Nuclear Data Sheets

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“…Since the contribution from the interference term approximately cancels out, the result of integration is similar to the capture kernel and reads [1] (see p.72, Eq.3.3) 21) where the cross section is restricted to the resonance term, σ res n (E). The average scattering cross section in sufficiently broad energy group of the width ∆E = E 1 − E 2 around the resonance energy E 0 can thus be obtained as 22) which is the sum of potential scattering and resonance scattering, 23) with the resonance term being similar to the expression for the average capture cross section.…”

Section: Low Energy Approximationmentioning

confidence: 99%

“…• Unknown spins are assigned by the code PTANAL using approach often adopted by evaluators of MF2 data [22]. The assignments are made statistically in accordance with spin distribution prescribed by nuclear level densities.…”

Section: Evaluation Proceduresmentioning

confidence: 99%

Formalism for neutron cross section covariances in the resonance region using kernel approximation

Obložinský¹,

Cho²

2010

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We describe analytical formalism for estimating neutron radiative capture and elastic scattering cross section covariances in the resolved resonance region. We use capture and scattering kernels as the starting point and show how to get average cross sections in broader energy bins, derive analytical expressions for cross section sensitivities, and deduce cross section covariances from the resonance parameter uncertainties in the recently published Atlas of Neutron Resonances. The formalism elucidates the role of resonance parameter correlations which become important if several strong resonances are located in one energy group. Importance of potential scattering uncertainty as well as correlation between potential scattering and resonance scattering is also examined. Practical application of the formalism is illustrated on 55 Mn(n,γ) and 55 Mn(n,el).

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“…Nd which is due to differences in the parameters of the bound level in the Atlas as compared to that of Oh et al [4], particularly the spin of the bound level. The other major difference between the present work and the Atlas value is the resonance capture integral of Nd capture cross sections and comparing them to ENDF/B-VI.8, JEFF-3.1 and JENDL-3.3 libraries and to the measurements.…”

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confidence: 76%

Evaluation of Neutron Cross Sections for a Complete Set of Nd Isotopes

Kim

Herman

Mughabghab

et al. 2008

Nuclear Science and Engineering

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Neutron cross sections for a complete set of Nd isotopes, 142,143,144,145,146,147,148,150 Nd, were evaluated in the incident energy range from 10 −5 eV to 20 MeV. In the low energy region, including thermal and resolved resonances, our evaluations are based on the latest data published in the Atlas of Neutron Resonances. In the unresolved resonance region we performed additional evaluation by using the averages of the resolved resonances and adjusting them to the experimental data. In the fast neutron region, we used the nuclear reaction model code EMPIRE-2.19 validated against the experimental data. The results are compared to the existing nuclear data libraries, including ENDF/B-VI.8, JENDL-3.3 and JEFF-3.1, and to the available experimental data. The new evaluations are suitable for neutron transport calculations and they were adopted by the new evaluated nuclear data file of the United States, ENDF/B-VII.0, released in December 2006. 24.10.Eq, 24.60.Dr, 24.60.Gv, 25.40.Fq * Corresponding author.Email addresses: hikim@kaeri.re.kr (Hyeong Il Kim), mwherman@bnl.gov (M. Herman), mugabgab@bnl.gov (S. F. Mughabghab), oblozinsky@bnl.gov (P. Obložinský), rochman@nrg-nl.com, present address NRG, PO Box 25, 1755 ZG Petten, The Netherlands (D. Rochman), yolee@kaeri.re.kr (Young-Ouk Lee).

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Neutron Cross Section Evaluations of Fission Products Below the Fast Energy Region

Cited by 28 publications

References 1 publication

Neutron Cross Section Uncertainties in the Thermal and Resonance Regions

Neutron Cross Section Uncertainties in the Thermal and Resonance Regions

Formalism for neutron cross section covariances in the resonance region using kernel approximation

Evaluation of Neutron Cross Sections for a Complete Set of Nd Isotopes

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