The effect of scintillator geometry on the quality of neutron/γ pulse shape discrimination (PSD) in EJ-299 plastic scintillator, using a digital charge integration PSD algorithm has been studied. It is shown that the PSD Figure of Merit (FOM) reduces as the geometry of the scintillator moves from a cube-like shape towards a flat panel shape. The PSD performance in this material at high flux irradiation is investigated with performance deteriorating at rates of ~107 photons/s. The use of EJ-299 for security applications, with a focus on active interrogation environments is explored in conjunction with a system capable of neutron/γ separation and localisation.