Dependence of $$\bar v$$ on neutron energies up to 5 MeV for233U,238U, and239Pu

Nurpeisov, B.; Volodin, K.E.; Nesterov, V.G.; Prokhorova, L. I.; Smirenkin, G.N.; Turchin, Yu. M.

doi:10.1007/bf01122383

Cited by 14 publications

(5 citation statements)

References 7 publications

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“…Ref. [6,7,8,9,10,11,12,13,14,13,14,15,16,17,18,19,20,21,22,23,24,25]. I am happy to report that I am satisfied with the level of development of technical skill that I was afforded to achieve this summer.…”

Section: Description Of the Research Projectmentioning

confidence: 97%

Modeling Systematic Discrepancies in Nuclear-Data Measurements with Machine Learning

Michael

2020

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Nuclear data and their associated co-variances are constantly being reevaluated as techniques improve and as new experimental data, as well as nuclearmodel developments, emerge. A standard technique used to evaluate mean values in nuclear data, and their associated covariances, is the generalized linear least squares (GLLS) method. Aligning with recent efforts to incorporate measurement features into nuclear data evaluation, we augment GLLS by including a linear term which attempts to predict potential systematic discrepancies in experimental data as related to the measurement features. Due to the general nature of this augmentation, we are able to apply this evaluation to three key observables: neutroninduced fission cross sections, the average prompt neutron multiplicity, and the prompt-fission neutron spectrum of 239 Pu.

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Section: Description Of the Research Projectmentioning

confidence: 97%

Modeling Systematic Discrepancies in Nuclear-Data Measurements with Machine Learning

Michael

2020

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“…The systematics presented in [47] was employed to determine partial multiplicities of prompt fission neutrons, ν x , for excitation energies below the threshold for emissive fission in the reactions 235−238 U(n, f ). This approach makes it possible to describe data on ν(E n ) [48][49][50][51][52][53] up to E n = 20 MeV. The spectra S A+2−x (ε, E n ) of neutrons emitted by fragments of each of the (A + 2 − x) nuclei undergoing fission were approximated by a superposition of two Watt distributions [35]; that is,…”

Section: Prompt-fission-neutron Spectramentioning

confidence: 99%

10.1007/s11450-008-1002-2

2010

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The spectra of prompt fission neutrons from the reaction 238 U(n, F ) for neutrons of energy in the range E n ≤ 20 MeV are interpreted within the statistical model. It is shown that exclusive spectra of prefission neutrons emitted in (n, xnf ) reactions play a decisive role in describing the observed promptfission-neutron spectra and determine the average energies of prompt-fission neutrons. The dependence of the effect of prefission neutrons on the fissility of a target nucleus is demonstrated for the reactions

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“…The process of prompt emission after fission has been investigated experimentally and theoretically since the 1940s [1], but open questions remain. For instance, the average number of prompt fission neutrons emitted, ] p , has been measured repeatedly with uncertainties as low as 0.75% for 239 Pu [2][3][4][5], but experimenters almost always employed the liquid scintillator technique [6][7][8][9]. The 239 Pu(n,f) cross sections were primarily measured with fission chambers with uncertainties ranging typically from 1.2% to 1.5% [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Shedding light on the 239Pu fission source term with new high-precision experiments and advanced fission modeling

et al. 2023

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In the last decade, there has been a renaissance of fission research resulting in new high-precision experiments and advanced fission modeling. For instance, the Chi-Nu and CEA teams supplied, for the first time, the 239Pu prompt fission neutron spectrum (PFNS) for broad ranges of incident and outgoing neutron energies. The CEA team also measured 239Pu average prompt neutron multiplicities, ν̄p, with lower statistical uncertainties and a technique significantly different than the one used in the past. The NIFFTE collaboration provided 239Pu(n,f)/235U(n,f) cross section shape ratios with uncertainties below 1% utilizing a novel detector type. Advanced fission event generators were developed, among them CGMF, FIFRELIN, FREYA, and GEF, which calculate post-scission fission observables in a correlated manner. These new experimental data and more consistent fission models change the evaluated PFNS, ν̄p, and (n,f) cross sections, some only modestly, compared to ENDF/B-VIII.0. In turn, the individual new nuclear data distinctly change simulated effective neutron multiplication factors of fast critical assemblies, but their combined impact is small, while affecting the prediction of LLNL pulsed sphere neutron leakage spectra and reaction rates only within experimental uncertainties. Also, the parameters obtained from fitting to ν̄p reproduce various post-scission fission observables within the uncertainties of experimental data. This indicates that new differential experiments and consistent fission modeling reduce compensating errors present in ENDF/B-VIII.0.

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Dependence of $$\bar v$$ on neutron energies up to 5 MeV for233U,238U, and239Pu

Cited by 14 publications

References 7 publications

Modeling Systematic Discrepancies in Nuclear-Data Measurements with Machine Learning

Modeling Systematic Discrepancies in Nuclear-Data Measurements with Machine Learning

10.1007/s11450-008-1002-2

Shedding light on the 239Pu fission source term with new high-precision experiments and advanced fission modeling

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