A neutron generator for neutron radiography, comprising: a modular neutron source configured to generate an ion beam in a beam direction and comprising: a Titanium target arranged to be bombarded by the ion beam and having a surface comprising a first diameter emitting fast neutrons isotropically, and a pre-moderator, the target being embedded in the pre-moderator, the pre-moderator having a downstream surface in the beam direction, a portion of the fast neutrons moderated in passing through the pre-moderator and exiting through the downstream surface of the pre-moderator; the neutron generator further comprising a plate of moderating material abutting the downstream surface of the pre-moderator, the plate having an upstream surface, in the beam direction, a downstream surface, a thickness, and an opening therethrough in a shape of a truncated cone with an axis aligning with the first direction of the ion beam, a depth, a major diameter at the upstream surface of the plate and a minor diameter at the downstream surface of the plate, the opening forming a funnel through which neutrons pass, the funnel being arranged such that neutrons exiting the pre-moderator through the downstream surface thereof enter the funnel and are collimated through the funnel to exit through the minor diameter of the funnel, providing a neutron beam with a spot size useful for neutron radiography, characterized in that the thickness of the plate of moderating material is greater than the depth of the funnel, further comprising a sleeve of high-density neutron reflecting material having an inside diameter equal to the major diameter of the truncated cone shape of the funnel, the sleeve lining a circular hole in the plate of moderating material, the hole having a first depth from the upstream surface to the major diameter of the truncated cone shape of the funnel, such that the depth of the circular hole and the depth of the funnel equals the thickness of the plate, and the inside diameter of the sleeve of reflecting material meets the major diameter of the truncated cone shape of the funnel. a Titanium target arranged to be bombarded by the ion beam and having a surface comprising a first diameter emitting fast neutrons isotropically, and a pre-moderator, the target being embedded in the pre-moderator, the pre-moderator having a downstream surface in the beam direction, a portion of the fast neutrons moderated in passing through the pre-moderator and exiting through the downstream surface of the pre-moderator; the neutron generator further comprising a plate of moderating material abutting the downstream surface of the pre-moderator, the plate having an upstream surface, in the beam direction, a downstream surface, a thickness, and an opening therethrough in a shape of a truncated cone with an axis aligning with the first direction of the ion beam, a depth, a major diameter at the upstream surface of the plate and a minor diameter at the downstream surface of the plate, the opening forming a funnel through which neutrons pass, the funnel being arranged such that neutrons exiting the pre-moderator through the downstream surface thereof enter the funnel and are collimated through the funnel to exit through the minor diameter of the funnel, providing a neutron beam with a spot size useful for neutron radiography, characterized in that the thickness of the plate of moderating material is greater than the depth of the funnel, further comprising a sleeve of high-density neutron reflecting material having an inside diameter equal to the major diameter of the truncated cone shape of the funnel, the sleeve lining a circular hole in the plate of moderating material, the hole having a first depth from the upstream surface to the major diameter of the truncated cone shape of the funnel, such that the depth of the circular hole and the depth of the funnel equals the thickness of the plate, and the inside diameter of the sleeve of reflecting material meets the major diameter of the truncated cone shape of the funnel.