Research On Neutrino Spectra From Spent Nuclear Fuel At Daya Bay

Neutrino physics is one of the research hotspot of particle physics and cosmology, and it is the key to new phsics beyond the standard model. The neutrino oscillation has an important significance to some issues such as matter antimatter asymmetry and the origin of the world.613 is one of the basic parameters in neutrino mixing theory, of which the size is very important to the future research. Daya Bay reactor neutrino expriment is designed to precisely measure θ13 based on near/far relative measurement of neutrino flux and spectra.Reactor neutrino spectra mainly consists of four main fission nuclides spectrum, and such spectrum depends on the experimental measurements by ILL, ignoring the contribution of non-equilibrium radionuclide, and the neutrinos generated by long half-life isotopes decay will produce lasting effects. For precisely measurement of the reactor neutrino spectra, the nonequilibrium correction to reactor fission nuclides spectrum and the spectra from spent nuclear fuel(SNF) deserves concern. In previous study, long half-life isotopes in SNF are chose firstly, then the activity and neutrino spectrum of each isotope are calculated respectively in order to obtain antinuetrino spectra emitted from SNF. But most of such calculations are based on a simple model and ignored the neutron flux transformation in burnup process. Furthermore, the burnup data of SNF should be taken into account, while it was negligible in previous study.Aiming at the shortcomings of previous research on SNF spectra, this thesis adopted more sophistacated methods to calculate antinuetrino spectra and flux emitted from SNF. (1) Using program certified in nuclear engineering, considering the burnup of more than 2000 isotopes and the neutron flux transformation in burnup process, such measures ensure calculation of the activity with high accuracy. (2) Taking the burnup data of SNF into consideration, and the variation of SNF antimuetrino spectra as well. (3) On the basis of Daya Bay experimental results, we analyze the contribution of antineutrino spectra from SNF for the first time. Due to the lake of experimental data, the statistical error of the data analysis is larger, while within the error range, the experimental results are in good agreement with the theoretical expectations. At last, we estimate the contribution of antineutrino spectra from SNF in the 1.8～4.0MeV region through theoretical calculation, and the event rate contribution from the SNF through data analysis as well.