Determining reactor fuel type from continuous antineutrino monitoring

TL;DR

This study demonstrates that a hypothetical antineutrino detector can reliably identify reactor fuel types and monitor plutonium disposition by analyzing spectral data over time, with high detection probability and implications for nuclear safeguards.

Contribution

It introduces a method to determine reactor fuel types and burn-up states using spectral analysis of antineutrinos, including scenarios of fuel diversion and spectral distortions.

Findings

Four major fuel types can be distinguished with 95% probability.

Antineutrino spectral analysis can identify burn-up levels of MOX fuel.

Detection remains robust despite spectral distortions around 6MeV.

Abstract

We investigate the ability of an antineutrino detector to determine the fuel type of a reactor. A hypothetical 5t antineutrino detector is placed 25m from the core and measures the spectral shape and rate of antineutrinos emitted by fission fragments in the core for a number of 90 day periods. Our results indicate that four major fuel types can be differentiated from the variation of fission fractions over the irradiation time with a true positive probability of detection at 95%. In addition, we demonstrate that antineutrinos can identify the burn-up at which weapons-grade mixed-oxide (MOX) fuel would be reduced to reactor-grade MOX on average, providing assurance that plutonium disposition goals are met. In addition, we investigate removal scenarios where plutonium is purposefully diverted from a mixture of MOX and low-enriched uranium (LEU) fuel. Finally, we discuss how our analysis is impacted by a spectral distortion around 6MeV observed in the antineutrino spectrum measured from commercial power reactors.