We report a reanalysis of the reactor antineutrino energy spectra based on the new relative measurements of the ratio $R={{}^{e}S}_5/{{}^{e}S}_9$ between cumulative $\beta$ spectra from ${}^{235}\mathrm{U}$ and ${}^{239}\mathrm{Pu}$, performed at a research reactor in National Research Centre Kurchatov Institute (KI). A discrepancy with the $\beta$ spectra measured at Institut Laue-Langevin (ILL) was observed, indicating a steady excess of the ILL ratio by the factor of $1.054\pm 0.002$. We find a value of the ratio between inverse beta decay cross section per fission for ${}^{235}\mathrm{U}$ and ${}^{239}\mathrm{Pu}$: ${(}^5{\sigma }_f{/}^9{\sigma }_f{)}_{KI}=1.45\pm 0.03$, and then we reevaluate the converted antineutrino spectra for ${}^{235}\mathrm{U}$ and ${}^{238}\mathrm{U}$. We conclude that the new predictions are consistent with the results of Daya Bay and STEREO experiments.

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• Beta decay
• Electrons
• Neutrinos