Patent Number: 
Section: claims

1. An apparatus for producing radioisotopes comprising:an irradiation chamber;a compact, stand-alone, fast neutron generator disposed within the irradiation chamber configured to provide fast neutrons;NEU material disposed within the irradiation chamber;one or more NEU-receiving regions disposed within the irradiation chamber and configured to accommodate the NEU material; andone or more non-moderating neutron-reflecting regions disposed in the irradiation chamber; wherein the one or more non-moderating neutron-reflecting regions are configured to increase the path length traveled by at least some neutrons from the neutron generator before those neutrons leave the irradiation chamber; wherein the one or more non-moderating, neutron-reflecting regions disposed in the irradiation chamber comprise multiple elongated parallel outer tubular shells formed of non-moderating neutron-reflecting material; wherein each of the multiple elongated parallel outer tubular shells has an interior bore containing NEU; wherein the interior bore defines one of the one or more NEU-receiving regions; and wherein the irradiation chamber has a fill port disposed on the upward portion of the irradiation chamber and has a drain port disposed on the lower portion of the irradiation chamber. 2. The apparatus of claim 1 further comprising a neutron-absorbing outer containment vessel comprising walls that are disposed at least 0.5 meter from the outside of the irradiation chamber. 3. The apparatus of claim 1 further comprising a non-moderating neutron-reflecting wall disposed within the irradiation chamber and surrounding the multiple elongated parallel outer tubular shells formed of non-moderating neutron-reflecting material.