Fission yield covariances for JEFF: A Bayesian Monte Carlo method

Leray, O.; Rochman, D.; Fleming, Michael; Sublet, J.‐Ch.; Koning, A. J.; Vasiliev, A.; Ferroukhi, H.

doi:10.1051/epjconf/201714609023

Cited by 6 publications

(3 citation statements)

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“…The two approaches were used to determine the thermal cumulative fission yields of the Neodymium isotopes for 235 U. Prior covariance matrix was generated by randomly varying model parameters of the GEF code [20]. The obtained covariance matrix was then modified by adding defect model contributions calculated as the difference between the evaluated values from JEFF-3.…”

Section: A Methodologymentioning

confidence: 99%

Systematics of Nd cumulative fission yields for neutron-induced fission of 235U, 238U, 238Pu, 239Pu, 240Pu and 241Pu

et al. 2018

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Systematics of cumulative fission yields of the Neodymium isotopes for thermal and fast neutron fission of 235 U, 238 U, 238 Pu, 239 Pu, 240 Pu and 241 Pu were obtained by combining integral results from the PROFIL experiments with theoretical calculations from the GEF code. The systematic behavior with the Neodymium mass number (A =143, 145, 146, 148, 150) deduced from the experimental trends is consistent with the smooth variation predicted by the GEF calculations, excepted for the 238 U(n,f) reaction. For this system, isotopic and isotonic effects in fission-fragment shell structures are not adequately taken into account in the theoretical calculation. The obtained results also confirm the weak energy dependence of the Nd cumulative fission yields in the energy range of interest for thermal and sodium fast reactors. They suggest an energy dependency comparable to the experimental uncertainty which lies below 3%, for the 235 U, 239 Pu and 241 Pu fissile isotopes.

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Section: A Methodologymentioning

confidence: 99%

Systematics of Nd cumulative fission yields for neutron-induced fission of 235U, 238U, 238Pu, 239Pu, 240Pu and 241Pu

et al. 2018

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“…Covariance matrix assessment depends on the evaluation process and its validity assumes that all measurements are statistically in agreement. These last years, different covariance matrices have been suggested but the experimental part of those are neglected in covariance evaluation [1] [2][3] [4] or applications [5] [6]. In the first part we present an assessment methodology based on statistical test.…”

Section: Introductionmentioning

confidence: 99%

From fission yield measurements to evaluation: new statistical methodology applied to ²³⁵U(n_th, f ) mass yields

et al. 2020

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The study of fission yields has a major impact on the characterization and understanding of the fission process and is mandatory for reactor applications. The mass and isotopic yields of the fission fragments have a direct influence on the predictions of fuel burn-up and decay heat. Moreover, these data are requested for other studies as delayed neutron evaluation, antineutrino flux assessment or reactor program. Today, the lack of covariance matrix associated to evaluated fission yields induces overestimated uncertainties of mass yields since these observables result from the sum of isotopic and isomeric yields. Our collaboration starts a new program in the field of the evaluation of fission products in addition to the current experimental program. The goal is to define a new methodology of evaluation based on statistical tests in order to provide the best estimation with consistent sets of measurements. A ranking of solutions with associated covariance based on Shannon’s entropy criterion is proposed for the mass yields from 235 U(nth, f) reaction.

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“…Nevertheless, the covariance matrix depends on the evaluation process and its existence assumes that all measurements are statistically in agreement. These last years, different covariance matrices have been suggested but the experimental part of those are not taken into account [1][2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

From fission yield measurements to evaluation: status on statistical methodology for the covariance question

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Kessedjian

Chebboubi

et al. 2018

EPJ Nuclear Sci. Technol.

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Studies on fission yields have a major impact on the characterization and the understanding of the fission process and are mandatory for reactor applications. Fission yield evaluation represents the synthesis of experimental and theoretical knowledge to perform the best estimation of mass, isotopic and isomeric yields. Today, the output of fission yield evaluation is available as a function of isotopic yields. Without the explicitness of evaluation covariance data, mass yield uncertainties are greater than those of isotopic yields. This is in contradiction with experimental knowledge where the abundance of mass yield measurements is dominant. These last years, different covariance matrices have been suggested but the experimental part of those are neglected. The collaboration between the LPSC Grenoble and the CEA Cadarache starts a new program in the field of the evaluation of fission products in addition to the current experimental program at Institut Laue-Langevin. The goal is to define a new methodology of evaluation based on statistical tests to define the different experimental sets in agreement, giving different solutions for different analysis choices. This study deals with the thermal neutron induced fission of 235 U. The mix of data is non-unique and this topic will be discussed using the Shannon entropy criterion in the framework of the statistical methodology proposed. *

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Fission yield covariances for JEFF: A Bayesian Monte Carlo method

Cited by 6 publications

References 6 publications

Systematics of Nd cumulative fission yields for neutron-induced fission of 235U, 238U, 238Pu, 239Pu, 240Pu and 241Pu

Systematics of Nd cumulative fission yields for neutron-induced fission of 235U, 238U, 238Pu, 239Pu, 240Pu and 241Pu

From fission yield measurements to evaluation: new statistical methodology applied to ²³⁵U(n_th, f ) mass yields

From fission yield measurements to evaluation: status on statistical methodology for the covariance question

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Fission yield covariances for JEFF: A Bayesian Monte Carlo method

Cited by 6 publications

References 6 publications

Systematics of Nd cumulative fission yields for neutron-induced fission of 235U, 238U, 238Pu, 239Pu, 240Pu and 241Pu

Systematics of Nd cumulative fission yields for neutron-induced fission of 235U, 238U, 238Pu, 239Pu, 240Pu and 241Pu

From fission yield measurements to evaluation: new statistical methodology applied to 235U(nth, f ) mass yields

From fission yield measurements to evaluation: status on statistical methodology for the covariance question

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From fission yield measurements to evaluation: new statistical methodology applied to ²³⁵U(n_th, f ) mass yields