Reference worldwide model for antineutrinos from reactors

TL;DR

This paper develops a comprehensive worldwide model for reactor antineutrino emissions, accounting for uncertainties and long-term variations, to improve background estimation for geoneutrino detection experiments.

Contribution

It provides a detailed, site-dependent model of reactor antineutrino fluxes using IAEA data, including uncertainty estimates and long-term operational variations.

Findings

Overall site-dependent uncertainty of about 3% in the geoneutrino energy window.

A 2.4% increase in unoscillated event rate due to spent fuel storage.

Research reactors contribute less than 0.2% to the total reactor signal.

Abstract

Antineutrinos produced at nuclear reactors constitute a severe source of background for the detection of geoneutrinos, which bring to the Earth's surface information about natural radioactivity in the whole planet. In this framework we provide a reference worldwide model for antineutrinos from reactors, in view of reactors operational records yearly published by the International Atomic Energy Agency (IAEA). We evaluate the expected signal from commercial reactors for ongoing (KamLAND and Borexino), planned (SNO+) and proposed (Juno, RENO-50, LENA and Hanohano) experimental sites. Uncertainties related to reactor antineutrino production, propagation and detection processes are estimated using a Monte Carlo based approach, which provides an overall site dependent uncertainty on the signal in the geoneutrino energy window on the order of 3%. We also implement the off-equilibrium correction to the reference reactor spectra associated with the long-lived isotopes and we estimate a 2.4% increase of the unoscillated event rate in the geoneutrino energy window due to the storage of spent nuclear fuels in the cooling pools. We predict that the research reactors contribute to less than 0.2% to the commercial reactor signal in the investigated 14 sites. We perform a multitemporal analysis of the expected reactor signal over a time lapse of 10 years using reactor operational records collected in a comprehensive database published at www.fe.infn.it/antineutrino.