The LANSCE 100 MeV Isotope Production Facility
In the fall of 2004, construction was completed on a new beam line and target area at the Los Alamos Neutron Science Center (LANSCE). The new beam line diverges from the main LANSCE accelerator at the transition region between the 100 MeV drift tube linac and the 800 MeV side-coupled-cavity linac. The linac accelerates both positively charged (H+) and negatively charged (H-) beams simultaneously. A pulsed (kicker) magnet was installed in the transition region so that a portion of the H+ beam can be deflected into the new beam line without impacting H- beam operations. This allows a high intensity (up to 250 microampere) proton beam with a nominal energy of 100 MeV to be delivered to the target station for radioisotope production.
The Isotope Production Facility consists of two levels. The lower level is underground and houses the beam line and target systems. The upper level includes an equipment room and a hot cell. Targets are loaded and retrieved through the hot cell using special remote handling equipment. This makes it possible to insert and remove targets without entering the beam tunnel or otherwise impacting accelerator operations. The target station allows for irradiation of several targets simultaneously, each at a discrete energy range. This facility allows production of a wide range of radioisotopes to support medical diagnosis and treatment and scientific research.
The TA-48 Hot Cells Facility
The TA-48 hot cells consist of a connected bank of thirteen hot cells with a specialized function for each cell. The cells are each configured with 20 inches of ferro–phosphorous concrete to provide adequate shielding from the irradiated IPF targets and subsequent isotope products. The cells are rated to shield up to 1000 Ci of Co–60. The hot cell windows consist of three panes of successively thicker–leaded-glass, with specialized oil separating each window that is optically matched to the glass permitting a clear, undistorted view of the hot cell interior. Cells are connected to one another by a train that can be used to transport targets, chemicals, and equipment needed for a given operation. The facility is operated under cGMP (current Good Manufacturing Practices) and under the oversight of the US Food and Drug Administration, given that some of the materials produced there are designated as pharmaceutical ingredients for end use in humans.
Irradiated targets are introduced into the hot cell bank under heavy shielding. Once they are unpackaged and transferred to the desired cell for chemistry, the target casing is punched or cut to provide access to the target material inside. Target dissolution can then be performed, which usually involves an aqueous acidic solution, depending on the target material. In the case of rubidium metal targets, a hot cell must be purged with argon prior to sequential dissolution of the target material in isopropanol and water to control reactivity during this process. A variety of conventional wet-chemistry techniques are then performed in the hot cell–a set of tasks requiring operators to take years of training in the art of remote manipulation–to isolate the isotope of interest.
Final products undergo rigorous radioassay and analysis for stable isotopes to ensure that the product is free of impurities. Products are typically packaged in DOT Type A containers that can be shipped around the country and the world. The program has historically made over 250 shipments each year to domestic and foreign end users.