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Dose rate modeling and post irradiation measurements of the Isotope Production Facility (IPF) beamline, at the Los Alamos Neutron Science Center (LANSCE) accelerator have determined that a radiation shielding shutter is required to protect personnel from shine from irradiated targets for routine beam tunnel entries. This paper will describe radiation dose modeling, shielding calculations, and the fail-safe mechanical shutter design.

Until 2003, the existing configuration of the Los Alamos Neutron Scattering Center (LANSCE) switchyard did not allow simultaneous delivery of the H − beam to Lines D and X. In the late 1990's, with increased activities in Areas B and C, which serve the ultracold neutron experiments (UCN) and proton radiography (pRad), respectively, planning began to increase beam availability to all areas by installing a kicker system, dubbed the "Switchyard Kicker." The Switchyard Kicker is a system of two pulsed and two direct current magnets that enables simultaneous, uninterrupted beam delivery to Line D for the Lujan Center and the Weapons Neutron Research (WNR) Facility and, on request, a tailored H − beam pulse to Line X for the pRad and UCN research areas. The project received funding in July 2001 for design and implementation. During the 2003 Extended Maintenance Period this upgrade was installed in the Switchyard and commissioned during the Accelerator Turn-On period in the summer of 2003. With the commissioning successful, LANSCE now routinely operates in "Kick" mode, delivering simultaneous beam to Line X and Line D, increasing beam availability to all areas and simplifying production scheduling.