An anti-neutrino detector to monitor nuclear reactor's power and fuel composition

In this contribution, we present the expected performance of a new detector to measure the absolute energy-integrated flux and the energy spectrum of anti-neutrinos emitted by a nuclear power plant. The number of detected anti-neutrino is a direct measure of the power while from the energy spectrum is possible to infer the evolution in time of the core isotopic composition. The proposed method should be sensitive to a sudden change in the core burn-up as caused, for instance, by a fraudulent subtraction of plutonium. The detector, a 130×100×100cm3 cube with 1m3 active volume, made by plastic scintillator wrapped in thin Gd foils, is segmented in 50 independent optical channels read, side by side, by a pair of 3 in. photomultipliers. Anti-neutrino interacts with hydrogen contained in the plastic scintillator via the neutron inverse ββ- decay (ν¯p→e+n). The high segmentation of the detector allows to reduce the background from other reactions by detecting independent hits for the positron, the two photons emitted in the e+e-e+e- annihilation and the neutron.