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

Kessedjian, G.; Cheikh, Sidi Mohamed; Chebboubi, A.; Sérot, O.

doi:10.1051/epjconf/202024205001

Cited by 6 publications

(5 citation statements)

References 11 publications

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“…The matrices displayed are the ones associated with the best estimate method analysis. This experimental matrix is different from evaluated fission yields [1,56,57]. For instance in the…”

Section: Appendix C4: Complementary Resultsmentioning

confidence: 95%

Measurements of $$^{233}$$U$$(\text {n}_{\text {th}},\text {f})$$ fission product mass yields with the LOHENGRIN recoil mass spectrometer

et al. 2021

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Numerous measurements of fission product yields were performed since the discovery of the nuclear fission process. However, more precise and reliable fission product yields are requested. Lack of covariance matrices make difficult to use it for specific application purposes such as the propagation uncertainty of decay heat. In this work, we propose to measure independently the fission product mass yields for the whole heavy peak (including the symmetric mass region) for the 233 U(n th , f) reaction. Both average values and experimental covariance is provided. The fission product mass yields are measured with the LOHEN-GRIN recoil mass spectrometer of the ILL using an ionization chamber located at the focal plane. A new procedure of data taking has been developed in order to minimize the biases. Concretely several ionic charges and kinetic energy distributions have been measured for each mass. Particular attention has been considered in the monitoring of the target time evolution. Additional corrections were necessary in the symmetry mass region due to contaminants coming from the LOHENGRIN recoil mass spectrometer. A complex Monte Carlo analysis has been developed in order to better propagate all the uncertainties. The fission product mass yields of the 233 U(n th , f) and its associated covariance matrix has been produced. An overall good agreement has been observed with ENDF/B-VIII.0 in contrast with the JEFF-3.3 evaluation. A precision around 2% for the heavy peak has been measured. The experimental covariance matrix was also computed. In the symmetry mass region, two components were observed in the kinetic energy distribution. One of this component was considered as an artifact and was ruled-out.

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“…The matrices displayed are the ones associated with the best estimate method analysis. This experimental matrix is different from evaluated fission yields [1,56,57]. For instance in the…”

Section: Appendix C4: Complementary Resultsmentioning

confidence: 95%

Measurements of $$^{233}$$U$$(\text {n}_{\text {th}},\text {f})$$ fission product mass yields with the LOHENGRIN recoil mass spectrometer

et al. 2021

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“…10). The rigorous statistical analysis [15,18] allows us to propose a synthesis of experimental data converging to quasi-null correlations of mass yields (see Fig. 11 & §2).…”

Section: New Complete Evaluation Of 235 U(nthf) Proposed To Jeff-4mentioning

confidence: 99%

“…14 illustrates the dependence in the choice of reference dataset that maximizes or minimizes the information provided. The quantification of information is deduced from the Shannon entropy [18] This result corresponds to non-ergodic analysis paths. The second limit of this process is that the tested mass rates are reduced to the overlapping mass rates (white cross).…”

Section: Multiplicity Of Mass Yield Evaluationsmentioning

confidence: 99%

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Covariance analysis of ²³⁵U(n_th,f) independent and cumulative fission yields: Propositions for JEFF4

Kessedjian

Cheikh²,

Serot³

et al. 2023

EPJ Web Conf.

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The study of fission yields has a major impact on the characterization and understanding of the fission process and its applications. Fission yield evaluations represent the synthesis of experimental and theoretical knowledge in order to perform the best estimation of independent fission yields. Today, the lack of correlations between the different fission observables induces several inconsistencies in the evaluations. Different works proposed to estimate the correlations of the independent fission yields satisfying the consistency to the chain yield evaluations. Nevertheless, none of them introduces a prior correlations of the independent and chain evaluations in the evaluation process. Covariance matrix of fission yields depends on the evaluation method used according to the kinds of existing measurements. The consistency is deeply entangled to the statistical agreement between each dataset considering the covariance of measurements. Moreover, covariance of model parameters does not represent the only contribution to the evaluation covariance matrix. Thus, a new evaluation process is crucial to provide a complete and coherent evaluation file. The LEPh Laboratory of CEA Cadarache is developing this program for the future version of the JEFF-library.

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“…In this calculation, we arbitrarily add 1% to 3% of systematic uncertainties (filling in the covariance elements) and we compare the results for the same data selection. The analyzed values are the mean values, the relative uncertainties and the correlation matrix (Figs 13 2 presents the Shannon entropy calculated using the eigenvalues of the different correlation matrices [25].…”

Section: Impact Of Experimental Correlation In the Evaluationsmentioning

confidence: 99%

From fission yield measurements to evaluation: Propositions of ²³⁵U(n_th,f) Fission Yields for JEFF-4

et al. 2023

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The study of fission yields has a major impact on the characterization and understanding of the fission process and its applications. The fission products have a direct influence on the amount of neutron poisons that limit the fuel burnup and on the evaluation of the decay heat of the reactor after shutdown. Fission yield evaluation represents the synthesis of experimental and theoretical knowledge in order to perform the best estimation of mass and independent fission product yields. Today, the lack of correlations between the different fission observables induces some inconsistencies in the evaluations. For instance, the mass yield uncertainties are drastically overestimated while this observable is the best known. In this last decade, different covariance matrices have been proposed but the experimental part of those are neglected. A consistent covariance matrix depends on the global process of evaluation from data up to the models used. The collaboration develops a new methodology in the field of fission products for the future version of the JEFF-library coupling the analyses of the CEA and NNL institutes.

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

Cited by 6 publications

References 11 publications

Measurements of $$^{233}$$U$$(\text {n}_{\text {th}},\text {f})$$ fission product mass yields with the LOHENGRIN recoil mass spectrometer

Measurements of $$^{233}$$U$$(\text {n}_{\text {th}},\text {f})$$ fission product mass yields with the LOHENGRIN recoil mass spectrometer

Covariance analysis of ²³⁵U(n_th,f) independent and cumulative fission yields: Propositions for JEFF4

From fission yield measurements to evaluation: Propositions of ²³⁵U(n_th,f) Fission Yields for JEFF-4

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

Cited by 6 publications

References 11 publications

Measurements of $$^{233}$$U$$(\text {n}_{\text {th}},\text {f})$$ fission product mass yields with the LOHENGRIN recoil mass spectrometer

Measurements of $$^{233}$$U$$(\text {n}_{\text {th}},\text {f})$$ fission product mass yields with the LOHENGRIN recoil mass spectrometer

Covariance analysis of 235U(nth,f) independent and cumulative fission yields: Propositions for JEFF4

From fission yield measurements to evaluation: Propositions of 235U(nth,f) Fission Yields for JEFF-4

Contact Info

Product

Resources

About

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

Covariance analysis of ²³⁵U(n_th,f) independent and cumulative fission yields: Propositions for JEFF4

From fission yield measurements to evaluation: Propositions of ²³⁵U(n_th,f) Fission Yields for JEFF-4