Nonfuel Antineutrino Contributions in the High Flux Isotope Reactor

Abstract

Reactor neutrino experiments have seen major improvements in precision in recent years. With the experimental uncertainties becoming lower than those from theory, carefully considering all sources of ${\overline{\nu }}_e$ is important when making theoretical predictions. One source of ${\overline{\nu }}_e$ that is often neglected arises from the irradiation of the nonfuel materials in reactors. The ${\overline{\nu }}_e$ rates and energies from these sources vary widely based on the reactor type, configuration, and sampling stage during the reactor cycle and have to be carefully considered for each experiment independently. In this article, we present a formalism for selecting the possible ${\overline{\nu }}_e$ sources arising from the neutron captures on reactor and target materials. We apply this formalism to the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory, the ${\overline{\nu }}_e$ source for the the Precision Reactor Oscillation and Spectrum Measurement (PROSPECT) experiment. Overall, we observe that the nonfuel ${\overline{\nu }}_e$ contributions from HFIR to PROSPECT amount to 1\% above the inverse beta decay threshold with a maximum contribution of 9\% in the 1.8--2.0~MeV range. Nonfuel contributions can be particularly high for research reactors like HFIR because of the choice of structural and reflector material in addition to the intentional irradiation of target material for isotope production. We show that typical commercial pressurized water reactors fueled with low-enriched uranium will have significantly smaller nonfuel ${\overline{\nu }}_e$ contribution.

References in corpus (27)

• The Reactor Antineutrino Anomaly
• Improved Predictions of Reactor Antineutrino Spectra
• On the determination of anti-neutrino spectra from nuclear reactors
• Observation of Coherent Elastic Neutrino-Nucleus Scattering
• Observation of Energy and Baseline Dependent Reactor Antineutrino Disappearance in the RENO Experiment
• Measurement of Neutrino-Electron Scattering Cross-Section with a CsI(Tl) Scintillating Crystal Array at the Kuo-Sheng Nuclear Power Reactor
• Systematic Uncertainties in the Analysis of the Reactor Neutrino Anomaly
• A new measurement of antineutrino oscillation with the full detector configuration at Daya Bay
• Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay
• Improved measurements of the neutrino mixing angle ${\theta }_{13}$ with the Double Chooz detector
• New antineutrino energy spectra predictions from the summation of beta decay branches of the fission products
• Spectral Structure of Electron Antineutrinos from Nuclear Reactors
• The Possible Origin and Implications of the Shoulder in Reactor Neutrino Spectra
• Exploring CEvNS with NUCLEUS at the Chooz Nuclear Power Plant
• Improved Calculation of Thermal Fission Energy
• Measurement of the Antineutrino Spectrum from ${}^{235}$U Fission at HFIR with PROSPECT
• Observation of the Isotopic Evolution of Pressurized Water Reactor Fuel Using an Antineutrino Detector
• Comparison of nuclear data uncertainty propagation methodologies for PWR burn-up simulations
• The STEREO Experiment
• Reactor antineutrino fluxes - status and challenges
• Performance of a full scale prototype detector at the BR2 reactor for the SoLid experiment
• Performance of a segmented ${}^6$Li-loaded liquid scintillator detector for the PROSPECT experiment
• Antineutrino monitoring of spent nuclear fuel
• Experimental Parameters for a Reactor Antineutrino Experiment at Very Short Baselines
• Impact of Fission Neutron Energies on Reactor Antineutrino Spectra
• Neutron capture and the antineutrino yield from nuclear reactors
• On Search for New Physics in Nonequilibrium Reactor Antineutrino Energy Spectrum

Cited by in corpus (3)

• Improved Short-Baseline Neutrino Oscillation Search and Energy Spectrum Measurement with the PROSPECT Experiment at HFIR
• Final Measurement of the U235 Antineutrino Energy Spectrum with the PROSPECT-I Detector at HFIR
• PROSPECT-II Physics Opportunities