Calculation of low-energy electron antineutrino spectra emitted from nuclear reactors with consideration of fuel burn-up

Nuclear reactors produce a great number of electron antineutrinos mainly from beta-decay chains of fission products (FP). Such neutrinos have energies mostly in MeV range. We are interested in neutrinos in a region of keV, since they may have information on fuel burn-up and may be detected in the future with advanced measurement technology. We calculate reactor antineutrino spectra especially in the low-energy region. In this work, we present neutrino spectra from various reactors such as typical pressurized water reactor and others types of reactors for comparison. Our result shows the electron antineutrino flux in the low-energy region increases with burn-up of nuclear fuel by accumulated nuclides with low Q values in beta-decay.