Exclusion and Verification of Remote Nuclear Reactors with a 1-Kiloton Gd-Doped Water Detector

TL;DR

This paper evaluates the potential of a 1-kiloton gadolinium-doped water Cherenkov detector for non-intrusive remote monitoring and verification of nuclear reactors over large distances, demonstrating its ability to exclude undeclared reactors within tens of kilometers.

Contribution

It quantifies the exclusion and detection capabilities of a large-scale water Cherenkov detector for reactor monitoring using likelihood analysis.

Findings

Can exclude gigawatt reactors up to tens of km away within a year.

Energy resolution insufficient to precisely identify reactor range and power.

Supports non-intrusive, offsite nuclear reactor verification.

Abstract

To date, antineutrino experiments built for the purpose of demonstrating a nonproliferation capability have typically employed organic scintillators, were situated as close to the core as possible -typically a few meters to tens of meters distant and have not exceeded a few tons in size. One problem with this approach is that proximity to the reactor core require accommodation by the host facility. Water Cherenkov detectors located offsite, at distances of a few kilometers or greater, may facilitate non-intrusive monitoring and verification of reactor activities over a large area. As the standoff distance increases, the detector target mass must scale accordingly. This article quantifies the degree to which a kiloton-scale gadolinium-doped water-Cherenkov detector can exclude the existence of undeclared reactors within a specified distance, and remotely detect the presence of a hidden reactor in the presence of declared reactors, by verifying the operational power and standoff distance using a Feldman-Cousins based likelihood analysis. A 1-kton scale (fiducial) water Cherenkov detector can exclude gigawatt-scale nuclear reactors up to tens of kilometers within a year. When attempting to identify the specific range and power of a reactor, the detector energy resolution was not sufficient to delineate between the two.