Reactor Antineutrino Signals at Morton and Boulby

Increasing the distance from which an antineutrino detector is capable of monitoring the operation of a registered reactor, or discovering a clandestine reactor, strengthens the Non-Proliferation of Nuclear Weapons Treaty. This report presents calculations of the reactor antineutrino interactions, from both quasi-elastic neutrino-proton scattering and elastic neutrino-electron scattering, in a water-based detector operated & 10 km from a commercial power reactor. It separately calculates signal from the proximal reactor and background from all other registered reactors. The main results are the interaction rates and kinetic energy distributions of the charged leptons scattered from the quasi-elastic and elastic processes. Comparing signal and background distributions evaluates reactor monitoring capability. Scaling the results to detectors of different sizes, target media, and standoff distances is straightforward. Calculations are for two specific examples of a commercial reactor (Pth ∼ 3 GW) operating nearby (L ∼ 20 km) an underground facility capable of hosting a detector (∼ 1 kT H2O) project. These reactor-site combinations are Perry-Morton on the southern shore of Lake Erie in the United States and Hartlepool-Boulby on the western shore of the North Sea in England. The signal from the proximal reactor is about five times greater at the Morton site than at the Boulby site due to shorter reactor-site separation distance, larger reactor thermal power, and greater neutrino oscillation survival probability. In terms of absolute interaction rate, background from all other reactors is larger at Morton than at Boulby. However, the fraction of the total rate is smaller at Morton than at Boulby. Moreover, the Hartlepool power plant has two cores whereas the Perry plant has a single core. These conditions make monitoring the operation cycle of a nuclear reactor more challenging at the Boulby site than at the Morton site. The Boulby site, therefore, offers an opportunity for demonstrating remote reactor monitoring under more stringent conditions than does the Morton site.