Identifying Inconsistencies in Fission Product Yield Evaluations with Prompt Neutron Emission

Jaffke, P.

doi:10.1080/00295639.2018.1429173

Cited by 11 publications

(5 citation statements)

References 59 publications

(48 reference statements)

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“…Historically, there is little to no consistency between the various types of fission nuclear data in our evaluated libraries [1]. However, we know that these observables are correlated through the fission process that produces all of them.…”

Section: Introductionmentioning

confidence: 96%

Producing Evaluation-quality ²³⁹Pu Average Prompt Fission Neutron Multiplicities using a Correlated Fission Model

2023

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An evaluation of the average prompt fission neutron multiplicity, ν¯ p, of 239Pu(n,f) is shown. This evaluation includes (a) the correlated fission model CGMF, and (b) a detailed analysis of past and recently published experimental data. Using CGMF-calculated ν¯ pas prior enables to link, through the use of evaluated model input parameters, ν¯ p to other fission observables such as the prompt fission neutron spectrum (PFNS), pre-neutron emission fission yields as a function of mass, and the average total kinetic energy of the fragments. These evaluated parameters produce realistic predictions of many fission observables, while the evaluated ν¯ p agrees well (χ2 ≈ 1) with data. Moreover, with the new evaluated ν¯ p, the effective neutron multiplication factor of fast Pu ICSBEP critical assemblies are predicted with a mean bias of 58 pcm compared to 18 pcm with ENDF/B-VIII.0, when paired with a new 239Pu PFNS and fission cross section. Due to these encouraging validation results, the evaluated ν¯ p is currently part of a release candidate for the 239Pu ENDF/B-VIII.1 file. Hence, a correlated fission model was used for the first time for evaluating ν¯ p that is of evaluation quality. This is an important step towards consistent evaluations of prompt fission observables.

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Section: Introductionmentioning

confidence: 96%

Producing Evaluation-quality ²³⁹Pu Average Prompt Fission Neutron Multiplicities using a Correlated Fission Model

2023

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“…From there, the models ei- * e-mail: lovell@lanl.gov ther perform a Monte Carlo sampling of the fission fragment initial conditions and de-excite the fission fragments or deterministically de-excite the fragments. This type of consistent modeling of prompt and/or delayed neutron and γ-ray observables aims to solve the problem of discrepancies between evaluated quantities [20] caused by the use of independent modeling for quantities that are inherently linked.…”

Section: Introductionmentioning

confidence: 99%

The Extension of the Hauser-Feshbach Fission Fragment Decay Model to Multi-chance Fission and its Application to ²³⁹Pu

et al. 2023

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The Hauser-Feshbach fission fragment decay model, HF3D, calculates the statistical decay of fission fragments through both prompt and delayed neutron and γ-ray emissions in a deterministic manner. While previously limited to the calculation of only first-chance fission, the model has recently been extended to include multi-chance fission, up to neutron incident energies of 20 MeV. The deterministic decay takes as input prescission quantities–fission probabilities, pre-fission neutron energies, and the average energy causing fission– and post-scission quantities–yields in mass, charge, total kinetic energy, spin, and parity. From those fission fragment initial conditions, the full decay is followed through both prompt and delayed particle emissions. The evaporation of the prompt neutrons and γ rays is calculated through the Hauser-Feshbach statistical theory, taking into account the competition between neutron and γ-ray emission, conserving energy, spin, and parity. The delayed emission is taken into account using time-independent calculation using decay data. This whole formulation allows for the calculation of prompt neutron and γ-ray properties, such as multiplicities and energy distributions, both independent and cumulative fission yields, and delayed neutron observables, in a consistent framework. Here, we describe the implementation of multi-chance fission into the HF3D model, and show an example of prompt and delayed quantities beyond first-chance fission, using the example of neutron-induced fission on 239Pu. This expansion represents significant progress in consistently modeling the emission of prompt and delayed particles from fissile systems.

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“…Many models used for the calculation and evaluation of quantities relevant to applications, such as reactor design, understanding detector response in nuclear physics measurements [17,18], or stockpile stewardship, are independent of one another so there is no connection between the fission product yields (FPYs), multiplicity distribu-tions, or energy spectra. This independence has been shown to cause discrepancies between evaluated quantities [19]. Thus, a great investment has been made into developing models that can calculate these quantities consistently.…”

Section: Introductionmentioning

confidence: 99%

Extension of the Hauser-Feshbach Fission Fragment Decay Model to Multi-Chance Fission

Lovell,

Kawano,

Okumura

et al. 2020

Preprint

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The Hauser-Feshbach fission fragment decay model, HF 3 D, which calculates the statistical decay of fission fragments, has been expanded to include multi-chance fission, up to neutron incident energies of 20 MeV. The deterministic decay takes as input pre-scission quantities-fission probabilities and the average energy causing fission-and post-scission quantities-yields in mass, charge, total kinetic energy, spin, and parity. From these fission fragment initial conditions, the full decay is followed through both prompt and delayed particle emissions, allowing for the calculation of prompt neutron and γ properties, such as multiplicity and energy distributions, both independent and cumulative fission yields, and delayed neutron observables. In this work, we describe the implementation of multi-chance fission into the HF 3 D model, and show an example of prompt and delayed quantities beyond first-chance fission, using the example of neutron-induced fission on 235 U. This expansion represents significant progress in consistently modeling the emission of prompt and delayed particles from fissile systems.

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Identifying Inconsistencies in Fission Product Yield Evaluations with Prompt Neutron Emission

Cited by 11 publications

References 59 publications

Producing Evaluation-quality ²³⁹Pu Average Prompt Fission Neutron Multiplicities using a Correlated Fission Model

Producing Evaluation-quality ²³⁹Pu Average Prompt Fission Neutron Multiplicities using a Correlated Fission Model

The Extension of the Hauser-Feshbach Fission Fragment Decay Model to Multi-chance Fission and its Application to ²³⁹Pu

Extension of the Hauser-Feshbach Fission Fragment Decay Model to Multi-Chance Fission

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Identifying Inconsistencies in Fission Product Yield Evaluations with Prompt Neutron Emission

Cited by 11 publications

References 59 publications

Producing Evaluation-quality 239Pu Average Prompt Fission Neutron Multiplicities using a Correlated Fission Model

Producing Evaluation-quality 239Pu Average Prompt Fission Neutron Multiplicities using a Correlated Fission Model

The Extension of the Hauser-Feshbach Fission Fragment Decay Model to Multi-chance Fission and its Application to 239Pu

Extension of the Hauser-Feshbach Fission Fragment Decay Model to Multi-Chance Fission

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Producing Evaluation-quality ²³⁹Pu Average Prompt Fission Neutron Multiplicities using a Correlated Fission Model

Producing Evaluation-quality ²³⁹Pu Average Prompt Fission Neutron Multiplicities using a Correlated Fission Model

The Extension of the Hauser-Feshbach Fission Fragment Decay Model to Multi-chance Fission and its Application to ²³⁹Pu